Ideal Weight Calculator
Estimate your ideal body weight using the Devine and Robinson formulas alongside a healthy BMI range reference for your height and sex.
Values
Fill in the values and click Calculate to see results
Doctors and pharmacists use ideal weight formulas such as Devine and Robinson to calculate medication dosages. Many common drugs, including anaesthetics, anticoagulants, and chemotherapy agents, are dosed based on ideal body weight rather than actual body weight because drug distribution in adipose tissue differs from lean tissue. Using actual weight for these medications can lead to overdosing in patients with high body fat or underdosing in very lean patients. The Devine formula, published in 1974, was developed specifically for theophylline dosing in respiratory medicine and later adopted as the standard for a wide range of pharmaceutical calculations in hospitals worldwide.
Dietitians and nutritionists reference ideal weight estimates when designing meal plans for weight management, adjusting calorie and protein targets based on whether a client’s current weight is above or below the estimated ideal. Personal trainers use ideal weight as one of several reference points when setting realistic and healthy weight goals for clients who want to lose or gain body mass. Health and life insurance underwriters review ideal weight ranges alongside BMI, waist circumference, and medical history when assessing risk profiles and setting premium rates. Researchers in epidemiology and clinical nutrition use ideal weight formulas as standardised reference points in studies tracking weight-related health outcomes across populations.
This ideal weight calculator estimates four reference values for your height and biological sex: the Devine formula estimate, the Robinson formula estimate, and the healthy BMI range minimum and maximum. The Devine formula has been the clinical standard for medication dosing for over four decades. The Robinson formula, derived from NHANES I survey data published in 1983, gives slightly different estimates and is often preferred in nutrition research. The healthy BMI range of 18.5 to 24.9 provides the weight range that the World Health Organisation associates with the lowest all-cause mortality at the population level. Together, these four values give you a complete picture of the weight ranges that medical professionals use as reference points for different purposes. The visual scale and bar chart below help you compare the estimates at a glance.
Dietitians and nutritionists reference ideal weight estimates when designing meal plans for weight management, adjusting calorie and protein targets based on whether a client’s current weight is above or below the estimated ideal. Personal trainers use ideal weight as one of several reference points when setting realistic and healthy weight goals for clients who want to lose or gain body mass. Health and life insurance underwriters review ideal weight ranges alongside BMI, waist circumference, and medical history when assessing risk profiles and setting premium rates. Researchers in epidemiology and clinical nutrition use ideal weight formulas as standardised reference points in studies tracking weight-related health outcomes across populations.
This ideal weight calculator estimates four reference values for your height and biological sex: the Devine formula estimate, the Robinson formula estimate, and the healthy BMI range minimum and maximum. The Devine formula has been the clinical standard for medication dosing for over four decades. The Robinson formula, derived from NHANES I survey data published in 1983, gives slightly different estimates and is often preferred in nutrition research. The healthy BMI range of 18.5 to 24.9 provides the weight range that the World Health Organisation associates with the lowest all-cause mortality at the population level. Together, these four values give you a complete picture of the weight ranges that medical professionals use as reference points for different purposes. The visual scale and bar chart below help you compare the estimates at a glance.
What Is Ideal Body Weight?
Ideal body weight (IBW) is an estimate of the weight that is associated with the lowest health risk for a given height and biological sex. It is not a precise target that applies to every individual, but rather a population-level reference point that clinicians use for screening, dosing, and goal setting. The concept originated in the mid-20th century when life insurance companies observed that policyholders whose weights fell within certain ranges for their height had the lowest mortality rates. The Metropolitan Life Insurance Company published the first widely used ideal weight tables in 1943, which became the basis for the modern formulas used in clinical practice.
Ideal weight is distinct from healthy weight, although the two terms are often used interchangeably. Healthy weight refers specifically to the weight range corresponding to a BMI of 18.5 to 24.9, which the WHO defines as the range associated with the lowest disease risk. Ideal weight formulas such as Devine and Robinson produce a single number, not a range, and were derived from different data sets and for different purposes than the BMI classification system. The Devine formula was designed for medication dosing and tends to give lower estimates for shorter individuals. The Robinson formula was derived from a nationally representative health survey and tends to give higher estimates, particularly for women and taller individuals.
The formula estimates are sex-specific because men and women have different average body compositions, muscle mass distributions, and fat storage patterns. Both the Devine and Robinson formulas start from a base weight for a height of 5 feet (60 inches) and add a fixed amount per inch above that height. For the Devine formula, the base weight is 50 kg for men and 45.5 kg for women, with an addition of 2.3 kg per inch over 5 feet. The Robinson formula uses a base of 52 kg for men and 49 kg for women, with 1.9 kg per inch for men and 1.7 kg per inch for women. The different increments mean that the two formulas diverge at taller heights, giving users a useful range rather than a single point.
Ideal weight is distinct from healthy weight, although the two terms are often used interchangeably. Healthy weight refers specifically to the weight range corresponding to a BMI of 18.5 to 24.9, which the WHO defines as the range associated with the lowest disease risk. Ideal weight formulas such as Devine and Robinson produce a single number, not a range, and were derived from different data sets and for different purposes than the BMI classification system. The Devine formula was designed for medication dosing and tends to give lower estimates for shorter individuals. The Robinson formula was derived from a nationally representative health survey and tends to give higher estimates, particularly for women and taller individuals.
The formula estimates are sex-specific because men and women have different average body compositions, muscle mass distributions, and fat storage patterns. Both the Devine and Robinson formulas start from a base weight for a height of 5 feet (60 inches) and add a fixed amount per inch above that height. For the Devine formula, the base weight is 50 kg for men and 45.5 kg for women, with an addition of 2.3 kg per inch over 5 feet. The Robinson formula uses a base of 52 kg for men and 49 kg for women, with 1.9 kg per inch for men and 1.7 kg per inch for women. The different increments mean that the two formulas diverge at taller heights, giving users a useful range rather than a single point.
Formula
Both Devine and Robinson formulas calculate ideal weight from height in inches, starting with a base weight for 5 feet (152.4 cm) and adding a fixed increment per additional inch.
Where W is ideal weight in kilograms and Hₑₙ is height in inches. To convert centimetres to inches, divide by 2.54. The base weight of 5 feet (60 inches or 152.4 cm) is the reference height. Both formulas are designed for adults aged 18 and older and should not be used for children or adolescents without age-specific adjustments.
Real-World Applications of Ideal Weight Estimation
Clinical medication dosing is a widely established application of ideal weight formulas. The Devine formula is the standard reference for calculating doses of many intravenous anaesthetics, including propofol, etomidate, and thiopental, because these drugs distribute primarily in lean body tissue. Using actual body weight for an obese patient would result in a proportionally higher dose than needed, increasing the risk of adverse effects and prolonged recovery. Similarly, the Devine formula is used for aminoglycoside antibiotics such as gentamicin and tobramycin, where accurate dosing is critical to achieve therapeutic levels while avoiding nephrotoxicity and ototoxicity. The American Society of Anaesthesiologists (opens in new tab) recommends using ideal body weight for dosing several classes of perioperative medications.
In clinical nutrition and dietetics, ideal weight serves as a reference for estimating energy and protein requirements in hospitalised patients. The Mifflin-St Jeor equation, which estimates basal metabolic rate, uses actual body weight for normal-weight individuals but switches to ideal body weight for overweight and obese patients to avoid overestimating calorie needs. The same principle applies to protein targets in critically ill patients, where protein requirements are often calculated per kilogram of ideal body weight to ensure adequate intake without overfeeding. The Academy of Nutrition and Dietetics includes ideal body weight in its evidence-based nutrition practice guidelines for adult weight management and critical care nutrition.
In fitness and personal training, trainers use ideal weight estimates as guideline targets when designing weight loss and muscle gain programmes. A client with a current weight of 85 kg and an ideal weight estimate of 72 kg has a clear reference for a realistic weight loss target of 13 kg. Trainers monitor progress toward the ideal weight range over weeks and months, adjusting calorie and exercise prescriptions as the client approaches their goal. The healthy BMI range is also factored into the assessment, because the ideal formula estimates are single points while the BMI range provides an acceptable buffer zone. Clients are advised to aim for any weight within the healthy BMI range rather than fixating on a specific formula number.
In bariatric surgery and medical weight management, ideal weight is used to calculate excess body weight and percentage of excess weight lost after surgery. The standard definition of excess weight is the difference between the patient’s current weight and the ideal weight (typically using the Devine formula). A patient weighing 120 kg with an ideal weight of 70 kg has an excess weight of 50 kg. After surgery, successful outcomes are commonly defined as the loss of at least 50% of excess weight and maintained for five years or more. This framework is used by the American Society for Metabolic and Bariatric Surgery to evaluate surgical outcomes and by insurance companies to determine coverage eligibility for bariatric procedures.
In clinical nutrition and dietetics, ideal weight serves as a reference for estimating energy and protein requirements in hospitalised patients. The Mifflin-St Jeor equation, which estimates basal metabolic rate, uses actual body weight for normal-weight individuals but switches to ideal body weight for overweight and obese patients to avoid overestimating calorie needs. The same principle applies to protein targets in critically ill patients, where protein requirements are often calculated per kilogram of ideal body weight to ensure adequate intake without overfeeding. The Academy of Nutrition and Dietetics includes ideal body weight in its evidence-based nutrition practice guidelines for adult weight management and critical care nutrition.
In fitness and personal training, trainers use ideal weight estimates as guideline targets when designing weight loss and muscle gain programmes. A client with a current weight of 85 kg and an ideal weight estimate of 72 kg has a clear reference for a realistic weight loss target of 13 kg. Trainers monitor progress toward the ideal weight range over weeks and months, adjusting calorie and exercise prescriptions as the client approaches their goal. The healthy BMI range is also factored into the assessment, because the ideal formula estimates are single points while the BMI range provides an acceptable buffer zone. Clients are advised to aim for any weight within the healthy BMI range rather than fixating on a specific formula number.
In bariatric surgery and medical weight management, ideal weight is used to calculate excess body weight and percentage of excess weight lost after surgery. The standard definition of excess weight is the difference between the patient’s current weight and the ideal weight (typically using the Devine formula). A patient weighing 120 kg with an ideal weight of 70 kg has an excess weight of 50 kg. After surgery, successful outcomes are commonly defined as the loss of at least 50% of excess weight and maintained for five years or more. This framework is used by the American Society for Metabolic and Bariatric Surgery to evaluate surgical outcomes and by insurance companies to determine coverage eligibility for bariatric procedures.
Example 1
A 30-year-old woman with a height of 1.65 m wants to estimate her ideal body weight using both the Devine and Robinson formulas. Her height in inches is 165 ÷ 2.54 = 65.0 inches, which is 5 inches above the 5-foot (60-inch) reference height.
Solution
Apply the Devine formula for women: ideal weight = 45.5 + 2.3 × (height in inches − 60).
Apply the Robinson formula for women: ideal weight$$
$$= 49 + 1.7 × (height in inches − 60).
Both formulas produce nearly identical results for this height, which is common for women close to the 5-foot reference height.
Answer
57 to 58 kg is the ideal weight range for this height using the Devine formula. For a 1.65 m woman, both formulas agree closely, giving a target of approximately 57 to 58 kg.
Source: Devine BJ, Gentamicin Therapy. Drug Intelligence & Clinical Pharmacy, 1974
Common Ideal Weight Calculation Mistakes
Treating ideal weight as a precise target is the most frequent error. The Devine and Robinson formulas are population-level estimates with a standard error of approximately 5 to 7 kg, meaning that the true healthy weight for an individual can vary by 10 to 14 kg around the formula estimate depending on muscle mass, bone density, frame size, and body composition. A man with a Devine estimate of 72 kg may be perfectly healthy at 65 kg if he has a small frame and low muscle mass, or at 80 kg if he is muscular and large-framed. The formula provides a reference, not a prescription. Always use the healthy BMI range alongside the formula estimates for a more realistic target zone.
Confusing ideal weight formulas with BMI range. The Devine and Robinson formulas produce a single number, while the healthy BMI range produces a span from the minimum to maximum weight. A person with a Devine estimate that falls near the bottom of their BMI range may be at a healthy weight but below the formula estimate, and vice versa. The two reference systems serve different purposes: the formulas for clinical dosing and population benchmarks, and the BMI range for mortality risk screening. Neither system accounts for muscle mass, bone density, or individual variation in body composition.
Using the wrong height measurement introduces significant error. The formulas require height in inches, and converting from centimetres incorrectly (forgetting to divide by 2.54, or using the wrong conversion factor) produces large errors. A height of 175 cm incorrectly entered as 175 inches gives an absurd result. Conversely, entering 67.5 inches (171 cm) when the true height is 175 cm (68.9 inches) shifts the estimate by approximately 2 to 3 kg. Always measure your height against a wall with a stadiometer or a tape measure fixed to a wall, and remove your shoes before measuring.
Applying the formulas to children and adolescents. The Devine and Robinson formulas were developed for adult populations and are not appropriate for individuals under 18 years of age. Children and teenagers undergo rapid changes in height, weight, and body composition during growth and puberty, and their ideal weight is assessed using age- and sex-specific growth percentiles from the WHO or CDC growth charts. Using adult formulas for a 14-year-old produces estimates that may be dangerously misleading, particularly during growth spurts when weight normally increases faster than height over short periods.
Confusing ideal weight formulas with BMI range. The Devine and Robinson formulas produce a single number, while the healthy BMI range produces a span from the minimum to maximum weight. A person with a Devine estimate that falls near the bottom of their BMI range may be at a healthy weight but below the formula estimate, and vice versa. The two reference systems serve different purposes: the formulas for clinical dosing and population benchmarks, and the BMI range for mortality risk screening. Neither system accounts for muscle mass, bone density, or individual variation in body composition.
Using the wrong height measurement introduces significant error. The formulas require height in inches, and converting from centimetres incorrectly (forgetting to divide by 2.54, or using the wrong conversion factor) produces large errors. A height of 175 cm incorrectly entered as 175 inches gives an absurd result. Conversely, entering 67.5 inches (171 cm) when the true height is 175 cm (68.9 inches) shifts the estimate by approximately 2 to 3 kg. Always measure your height against a wall with a stadiometer or a tape measure fixed to a wall, and remove your shoes before measuring.
Applying the formulas to children and adolescents. The Devine and Robinson formulas were developed for adult populations and are not appropriate for individuals under 18 years of age. Children and teenagers undergo rapid changes in height, weight, and body composition during growth and puberty, and their ideal weight is assessed using age- and sex-specific growth percentiles from the WHO or CDC growth charts. Using adult formulas for a 14-year-old produces estimates that may be dangerously misleading, particularly during growth spurts when weight normally increases faster than height over short periods.
Why Ideal Weight Matters for Your Health
Weight relative to height is one of the strongest predictors of long-term health outcomes at the population level. The relationship between body weight and mortality follows a J-shaped curve, with the lowest risk occurring in the range that corresponds to a BMI of 20 to 25. Below this range, mortality risk increases due to undernutrition, osteoporosis, and impaired immune function. Above this range, risk rises with increasing weight due to cardiovascular disease, type 2 diabetes, hypertension, and certain cancers. The ideal weight formulas provide a single reference point within this optimal range, helping individuals and clinicians identify a reasonable weight target.
Medication safety is directly tied to ideal weight estimation. Drugs that distribute primarily in lean tissue, such as many anaesthetics, neuromuscular blocking agents, and aminoglycoside antibiotics, require dose adjustment based on ideal body weight. A 2020 study published in Anesthesia & Analgesia found that using actual body weight instead of ideal body weight for propofol induction doses resulted in a 40% higher incidence of hypotension in obese patients. For chemotherapy agents, dosing based on ideal weight rather than actual weight is standard practice for drugs with narrow therapeutic windows, because overestimating the dose can cause severe toxicity while underestimating it can compromise treatment efficacy. The National Comprehensive Cancer Network guidelines specify ideal body weight as the standard for dosing many chemotherapy regimens.
Ideal weight is not a measure of health on its own. It is a reference point that becomes meaningful when combined with other metrics. A person at their ideal weight may have high body fat, low muscle mass, and metabolic syndrome, while a person 10 kg above their ideal weight may be metabolically healthy with excellent fitness. Body composition, fat distribution (waist circumference), blood pressure, blood glucose, and lipid levels together provide a far more complete picture of health than ideal weight alone. Use the reference tables and additional tools linked on this page to build a fuller understanding of your health, and always interpret weight targets in the context of your individual body composition and overall health.
Medication safety is directly tied to ideal weight estimation. Drugs that distribute primarily in lean tissue, such as many anaesthetics, neuromuscular blocking agents, and aminoglycoside antibiotics, require dose adjustment based on ideal body weight. A 2020 study published in Anesthesia & Analgesia found that using actual body weight instead of ideal body weight for propofol induction doses resulted in a 40% higher incidence of hypotension in obese patients. For chemotherapy agents, dosing based on ideal weight rather than actual weight is standard practice for drugs with narrow therapeutic windows, because overestimating the dose can cause severe toxicity while underestimating it can compromise treatment efficacy. The National Comprehensive Cancer Network guidelines specify ideal body weight as the standard for dosing many chemotherapy regimens.
Ideal weight is not a measure of health on its own. It is a reference point that becomes meaningful when combined with other metrics. A person at their ideal weight may have high body fat, low muscle mass, and metabolic syndrome, while a person 10 kg above their ideal weight may be metabolically healthy with excellent fitness. Body composition, fat distribution (waist circumference), blood pressure, blood glucose, and lipid levels together provide a far more complete picture of health than ideal weight alone. Use the reference tables and additional tools linked on this page to build a fuller understanding of your health, and always interpret weight targets in the context of your individual body composition and overall health.
How to Determine Your Personal Healthy Weight
Follow these steps to use ideal weight estimates effectively as part of a broader health assessment.
Step 1: Measure your height accurately. Stand against a wall with your heels, buttocks, and shoulders touching the surface. Remove your shoes. Use a stadiometer or a flat object placed on your head to mark the wall. Measure from the floor to the mark. Record to the nearest 0.1 cm or 0.1 inch. Do not estimate your height by looking down at a tape measure held above your head, as this introduces parallax error of 1 to 3 cm.
Step 2: Enter your height. Type your height into the height field. Use the unit dropdown to switch between centimetres (cm), feet (ft), or inches (in). The calculator converts to centimetres automatically before applying the formulas.
Step 3: Select your biological sex. Choose male or female from the dropdown. The Devine and Robinson formulas use different base weights and per-inch increments for each sex.
Step 4: Review your results. The calculator displays four values: Devine formula, Robinson formula, healthy BMI minimum, and healthy BMI maximum. Switch between kilograms, pounds, and stone using the unit dropdown next to each result. The visual scale below the results shows where the Devine estimate falls relative to the healthy BMI range.
Step 5: Use the range, not the point. The true healthy weight for your individual body is likely somewhere between the Devine and Robinson estimates and within the BMI range. A reasonable personal target is any weight within the healthy BMI range that feels sustainable for your body type, activity level, and lifestyle. If your current weight is above the BMI maximum, aim for the upper end of the range first. If you are below the BMI minimum, aim for the lower end.
Step 6: Combine with other metrics. Ideal weight shows you a number. Body composition shows you what that number is made of. The BMI Calculator on this site assesses your current weight status using WHO standards. The Body Fat Percentage Calculator estimates your body composition using circumference measurements you can take at home. The BMR Calculator tells you your resting calorie needs for weight management planning. Together, these tools give you a well-rounded view of your body composition and metabolic health.
Step 1: Measure your height accurately. Stand against a wall with your heels, buttocks, and shoulders touching the surface. Remove your shoes. Use a stadiometer or a flat object placed on your head to mark the wall. Measure from the floor to the mark. Record to the nearest 0.1 cm or 0.1 inch. Do not estimate your height by looking down at a tape measure held above your head, as this introduces parallax error of 1 to 3 cm.
Step 2: Enter your height. Type your height into the height field. Use the unit dropdown to switch between centimetres (cm), feet (ft), or inches (in). The calculator converts to centimetres automatically before applying the formulas.
Step 3: Select your biological sex. Choose male or female from the dropdown. The Devine and Robinson formulas use different base weights and per-inch increments for each sex.
Step 4: Review your results. The calculator displays four values: Devine formula, Robinson formula, healthy BMI minimum, and healthy BMI maximum. Switch between kilograms, pounds, and stone using the unit dropdown next to each result. The visual scale below the results shows where the Devine estimate falls relative to the healthy BMI range.
Step 5: Use the range, not the point. The true healthy weight for your individual body is likely somewhere between the Devine and Robinson estimates and within the BMI range. A reasonable personal target is any weight within the healthy BMI range that feels sustainable for your body type, activity level, and lifestyle. If your current weight is above the BMI maximum, aim for the upper end of the range first. If you are below the BMI minimum, aim for the lower end.
Step 6: Combine with other metrics. Ideal weight shows you a number. Body composition shows you what that number is made of. The BMI Calculator on this site assesses your current weight status using WHO standards. The Body Fat Percentage Calculator estimates your body composition using circumference measurements you can take at home. The BMR Calculator tells you your resting calorie needs for weight management planning. Together, these tools give you a well-rounded view of your body composition and metabolic health.
Example 2
A 40-year-old man who is 1.80 m tall wants to know his ideal weight using the Devine and Robinson formulas. His height in inches is 180 ÷ 2.54 = 70.87 inches, which is 10.87 inches above the 5-foot reference height.
Solution
Apply the Devine formula for men: ideal weight = 50 + 2.3 × (height in inches − 60).
Apply the Robinson formula for men: ideal weight = 52 + 1.9 × (height in inches − 60).
The Devine formula produces a higher estimate than the Robinson formula for this height, which is expected since the Devine formula uses a larger per-inch increment.
Answer
75 kg is the ideal weight for a 1.80 m man using the Devine formula. The Robinson formula gives 72.7 kg. The healthy BMI range for this height is 59.9 to 80.6 kg.
Understanding the Difference Between Ideal Weight and Healthy Weight
Ideal weight and healthy weight are related but distinct concepts. Ideal weight refers to the single number produced by a formula such as Devine or Robinson. Healthy weight refers to the entire weight range corresponding to a BMI of 18.5 to 24.9. A person with a height of 170 cm has a healthy weight range of 53.5 to 72.0 kg. Their Devine estimate (for a male) is 66.5 kg, and their Robinson estimate is 69.3 kg. All four numbers fall within the healthy range, but they represent different reference points for different purposes.
The BMI-based healthy weight range is the standard weight reference in clinical medicine because it is endorsed by the WHO (opens in new tab), the CDC, and most national health authorities. A large body of epidemiological evidence supports the association between a BMI of 18.5 to 24.9 and the lowest all-cause mortality. The range is sex-neutral, meaning the same BMI cutoffs apply to both men and women. The advantage of a range over a single number is that it accounts for individual variation: two people of the same height can have different optimal weights based on their muscle mass, bone density, and body frame, and both can fall within the healthy range at different points.
The Devine and Robinson formulas add sex-specificity and a different methodological basis. They were derived from clinical observation and survey data rather than mortality statistics, which explains why their estimates differ from each other and from the BMI range. In practice, the most useful approach is to look at all four estimates together. If the Devine estimate is 68 kg, the Robinson estimate is 71 kg, and the healthy BMI range is 58 to 78 kg, then your personal target range is approximately 68 to 71 kg, with an acceptable buffer of 58 to 78 kg. This combined approach gives you the precision of the formulas and the safety margin of the BMI range.
The BMI-based healthy weight range is the standard weight reference in clinical medicine because it is endorsed by the WHO (opens in new tab), the CDC, and most national health authorities. A large body of epidemiological evidence supports the association between a BMI of 18.5 to 24.9 and the lowest all-cause mortality. The range is sex-neutral, meaning the same BMI cutoffs apply to both men and women. The advantage of a range over a single number is that it accounts for individual variation: two people of the same height can have different optimal weights based on their muscle mass, bone density, and body frame, and both can fall within the healthy range at different points.
The Devine and Robinson formulas add sex-specificity and a different methodological basis. They were derived from clinical observation and survey data rather than mortality statistics, which explains why their estimates differ from each other and from the BMI range. In practice, the most useful approach is to look at all four estimates together. If the Devine estimate is 68 kg, the Robinson estimate is 71 kg, and the healthy BMI range is 58 to 78 kg, then your personal target range is approximately 68 to 71 kg, with an acceptable buffer of 58 to 78 kg. This combined approach gives you the precision of the formulas and the safety margin of the BMI range.
Comparison of Ideal Weight Formulas
Comparison of four commonly cited ideal body weight formulas. The Devine and Robinson formulas are used in this calculator. The Miller and Hamwi formulas are included for reference. Each formula uses a different base weight and per-inch increment, producing different estimates at the same height.
| Formula | Year | Original Purpose | Men (base + per inch) | Women (base + per inch) |
|---|---|---|---|---|
| Devine | 1974 | Theophylline dosing | 50 kg + 2.3 kg/in | 45.5 kg + 2.3 kg/in |
| Robinson | 1983 | NHANES I survey reference | 52 kg + 1.9 kg/in | 49 kg + 1.7 kg/in |
| Miller | 1983 | Clinical reference | 56.2 kg + 1.41 kg/in | 53.1 kg + 1.36 kg/in |
| Hamwi | 1964 | Dietetics reference | 48 kg + 2.7 kg/in | 45.5 kg + 2.2 kg/in |
Ideal weight formulas do not account for body composition. The Devine formula was designed for calculating drug doses in hospitalised patients, not for assessing general health. It assumes a relationship between height and ideal weight that does not differentiate between muscle, bone, and fat. A muscular athlete and a sedentary person of the same height and sex receive the same ideal weight estimate, even though their body compositions differ dramatically. The formula also does not account for age, ethnicity, or frame size, all of which affect the relationship between weight and health outcomes.
None of the formulas were derived from modern, diverse populations. The Devine formula was developed in a small sample of hospital patients, predominantly white and male. The Robinson formula used NHANES I data collected between 1971 and 1974, which included a more representative sample but still excluded many demographic groups. Both formulas may be less accurate for individuals of Asian, African, or Hispanic descent, who may have different relationships between height, muscle mass, and body fat distribution. Research has shown that the Devine formula tends to underestimate ideal weight for Asian populations and overestimate for some African populations, but no widely accepted ethnicity-adjusted version of the formula exists.
Age reduces the accuracy of all formulas. Adults lose 3 to 8% of their muscle mass per decade after age 30, which changes their body composition even if height and weight remain stable. An ideal weight estimate designed for a 30-year-old may not be appropriate for a 70-year-old of the same height. Some geriatric guidelines suggest that a slightly higher BMI target (24 to 27) is associated with better outcomes in older adults because a modest amount of body fat provides metabolic reserve during illness. The formulas on this page do not include an age adjustment, so older users should interpret the estimates with caution and discuss weight targets with their healthcare provider.
None of the formulas were derived from modern, diverse populations. The Devine formula was developed in a small sample of hospital patients, predominantly white and male. The Robinson formula used NHANES I data collected between 1971 and 1974, which included a more representative sample but still excluded many demographic groups. Both formulas may be less accurate for individuals of Asian, African, or Hispanic descent, who may have different relationships between height, muscle mass, and body fat distribution. Research has shown that the Devine formula tends to underestimate ideal weight for Asian populations and overestimate for some African populations, but no widely accepted ethnicity-adjusted version of the formula exists.
Age reduces the accuracy of all formulas. Adults lose 3 to 8% of their muscle mass per decade after age 30, which changes their body composition even if height and weight remain stable. An ideal weight estimate designed for a 30-year-old may not be appropriate for a 70-year-old of the same height. Some geriatric guidelines suggest that a slightly higher BMI target (24 to 27) is associated with better outcomes in older adults because a modest amount of body fat provides metabolic reserve during illness. The formulas on this page do not include an age adjustment, so older users should interpret the estimates with caution and discuss weight targets with their healthcare provider.
Example 3
A person with a BMI of 27 and a waist circumference of 95 cm wants to understand their target weight range. Their height is 1.70 m and their current weight is 78 kg. The healthy BMI range is 18.5 to 24.9.
Solution
Calculate the healthy weight range for a height of 1.70 m. The healthy BMI range is 18.5 to 24.9.
Their current weight of 78 kg corresponds to a BMI of 78 ÷ 2.89 = 27.0, which is in the overweight category. They need to lose between 6 kg (to reach 72 kg, the upper end) and 24 kg (to reach 54 kg, the lower end).
Answer
For a height of 1.70 m, the healthy BMI range of 18.5 to 24.9 corresponds to 53.5 to 72.0 kg. The current weight of 78 kg (BMI 27) is 6 kg above the healthy range, requiring a loss of at least 6 kg to reach the upper boundary.
Source: WHO: BMI Classification, 2024
Body composition changes everything. Two individuals of the same height can have the same ideal weight estimate but completely different body compositions, health profiles, and optimal weights. A 180 cm man with a Devine estimate of 77.5 kg may be lean and muscular at 82 kg (6% above the estimate) or have excess body fat at 72 kg (7% below the estimate). The weight number alone does not tell you whether the person is healthy. Body fat percentage, measured by skinfold calipers, bioelectrical impedance, or DEXA scan, gives a far more accurate picture of metabolic health than body weight alone.
BMI Classification Reference
WHO classification of adult BMI. The healthy BMI range of 18.5 to 24.9 is used as the reference for the healthy minimum and maximum weight estimates in this calculator. Categories are population averages and may vary by ethnicity.
| BMI Range | Category |
|---|---|
| < 16.0 | Severe thinness |
| 16.0 – 16.9 | Moderate thinness |
| 17.0 – 18.4 | Mild thinness |
| 18.5 – 24.9 | Normal weight (healthy BMI) |
| 25.0 – 29.9 | Pre-obese (overweight) |
| 30.0 – 34.9 | Obese class I |
| 35.0 – 39.9 | Obese class II |
| ≥ 40.0 | Obese class III |
Muscle mass is denser than fat. One kilogram of muscle occupies approximately 20% less volume than one kilogram of fat. A muscular individual may appear lean and fit while weighing significantly more than the ideal formula estimate. The opposite is also true: a sedentary individual with low muscle mass may achieve the ideal weight estimate but still have a high body fat percentage and elevated health risk. This phenomenon, known as normal-weight obesity, affects an estimated 15 to 30% of adults with a normal BMI. The BMI range partially addresses this by providing a range rather than a single target, but only body fat measurement can resolve the ambiguity.
Frame size influences ideal weight. People with larger bone structures naturally weigh more than those with small frames at the same height. Wrist circumference, elbow breadth, and shoulder width are sometimes used to estimate frame size, and some older ideal weight charts included frame size adjustments. The Devine and Robinson formulas do not account for frame size, which means they may systematically underestimate ideal weight for large-framed individuals and overestimate for small-framed individuals. If you know you have a larger or smaller than average frame, adjust your target weight toward the higher or lower end of the healthy BMI range accordingly.
Frame size influences ideal weight. People with larger bone structures naturally weigh more than those with small frames at the same height. Wrist circumference, elbow breadth, and shoulder width are sometimes used to estimate frame size, and some older ideal weight charts included frame size adjustments. The Devine and Robinson formulas do not account for frame size, which means they may systematically underestimate ideal weight for large-framed individuals and overestimate for small-framed individuals. If you know you have a larger or smaller than average frame, adjust your target weight toward the higher or lower end of the healthy BMI range accordingly.
Ideal Weight Estimates for Common Heights (Male)
Ideal weight estimates for adult males at common heights. All values in kilograms. The Devine and Robinson estimates differ most at taller heights due to different per-inch increments.
| Height | Devine | Robinson | BMI Range |
|---|---|---|---|
| 160 cm (5 ft 3 in) | 55.0 kg | 57.1 kg | 47.4 – 63.8 kg |
| 165 cm (5 ft 5 in) | 58.7 kg | 60.9 kg | 50.4 – 67.8 kg |
| 170 cm (5 ft 7 in) | 62.4 kg | 64.6 kg | 53.5 – 72.0 kg |
| 175 cm (5 ft 9 in) | 66.1 kg | 68.4 kg | 56.6 – 76.3 kg |
| 180 cm (5 ft 11 in) | 69.8 kg | 72.1 kg | 59.9 – 80.6 kg |
| 185 cm (6 ft 1 in) | 73.5 kg | 75.9 kg | 63.3 – 85.2 kg |
| 190 cm (6 ft 3 in) | 77.2 kg | 79.6 kg | 66.7 – 89.8 kg |
Professional Applications of Ideal Weight Estimation
Pharmacotherapy and anaesthesia rely on ideal body weight as a standard dosing metric. The American College of Chest Physicians guidelines for sedation in mechanically ventilated patients specify using ideal body weight for propofol and dexmedetomidine dosing. The American Society of Anaesthesiologists practice guidelines for preoperative fasting and the use of pharmacologic agents recommend ideal body weight for calculating doses of several classes of intravenous anaesthetics. Many hospital formularies and electronic prescribing systems include ideal body weight calculations automatically when clinicians enter patient height and sex, ensuring that weight-based dosing is consistent across the institution.
In critical care and emergency medicine, ideal weight is used to estimate tidal volumes for mechanical ventilation. Lung-protective ventilation strategies require setting tidal volume based on predicted body weight, which is calculated using formulas nearly identical to the Devine formula, using height and sex. The ARDS Network trial, which established the standard of care for low-tidal-volume ventilation in acute respiratory distress syndrome, used predicted body weight derived from the Devine formula with minor modifications. A patient’s height and sex determine their target tidal volume of 6 to 8 mL per kilogram of predicted body weight, making the ideal weight calculation a life-critical part of respiratory management in intensive care units worldwide.
In bariatric medicine, ideal body weight is the reference for calculating excess weight and tracking surgical outcomes. The American Society for Metabolic and Bariatric Surgery standardised outcome reporting guidelines require reporting percentage of excess weight loss, defined as (weight lost / excess weight) × 100, where excess weight equals preoperative weight minus ideal weight. Insurance companies use the same calculation to determine whether a patient meets the criteria for bariatric surgery coverage. A patient with a BMI of 40 or higher, or a BMI of 35 with obesity-related comorbidities, is eligible for surgery. The ideal weight calculation determines the target weight that defines a successful outcome, making it a central metric in the entire bariatric surgery pathway.
In critical care and emergency medicine, ideal weight is used to estimate tidal volumes for mechanical ventilation. Lung-protective ventilation strategies require setting tidal volume based on predicted body weight, which is calculated using formulas nearly identical to the Devine formula, using height and sex. The ARDS Network trial, which established the standard of care for low-tidal-volume ventilation in acute respiratory distress syndrome, used predicted body weight derived from the Devine formula with minor modifications. A patient’s height and sex determine their target tidal volume of 6 to 8 mL per kilogram of predicted body weight, making the ideal weight calculation a life-critical part of respiratory management in intensive care units worldwide.
In bariatric medicine, ideal body weight is the reference for calculating excess weight and tracking surgical outcomes. The American Society for Metabolic and Bariatric Surgery standardised outcome reporting guidelines require reporting percentage of excess weight loss, defined as (weight lost / excess weight) × 100, where excess weight equals preoperative weight minus ideal weight. Insurance companies use the same calculation to determine whether a patient meets the criteria for bariatric surgery coverage. A patient with a BMI of 40 or higher, or a BMI of 35 with obesity-related comorbidities, is eligible for surgery. The ideal weight calculation determines the target weight that defines a successful outcome, making it a central metric in the entire bariatric surgery pathway.
Example 4
A 28-year-old man is 180 cm tall with a large frame. What is his ideal weight range using the Devine formula and frame adjustment?
Solution
Large frame adjustment (+10%): 75.2 × 1.10 = 82.7 kg.
Healthy BMI range (18.5-24.9) for 180 cm: 60.0-80.7 kg. With large frame, upper end is more appropriate.
Answer
Devine ideal: 75.2 kg. With large frame: 82.7 kg. BMI range: 60-81 kg.
Source: Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm, 1974
Important Considerations When Using Ideal Weight Estimates
Ideal weight formulas are estimates, not prescriptions. They provide population-level reference points that help clinicians and individuals set reasonable weight targets. They are not diagnostic tools and cannot tell you whether you are healthy. A person whose current weight is 5 kg above their Devine estimate may be in excellent health, while a person at their exact Devine estimate may have metabolic syndrome. Always interpret ideal weight in the context of your overall health picture: blood pressure, fasting glucose, lipid panel, waist circumference, body fat percentage, and lifestyle factors such as diet, exercise, sleep, and stress.
Do not use ideal weight as the sole measure of weight-related health. Body composition matters more than body weight. A person at their ideal weight but with high body fat percentage and low muscle mass has a higher health risk than a person 5 kg above their ideal weight with low body fat and high muscle mass. If you are active and muscular, expect your healthy weight to be above the formula estimates. If you are sedentary with low muscle mass, your healthy weight may be below the estimates. The BMI range gives you a wider target zone that is more forgiving of individual variation than a single formula estimate.
Trends matter more than a single measurement. Tracking your weight over time and noting whether it is moving toward or away from your healthy weight range is more informative than comparing a single reading to a formula. A gradual increase from 2 kg below your ideal estimate to 5 kg above it over two years signals a trend that warrants attention, even if each individual reading is within the healthy BMI range. Conversely, a stable weight that is 3 kg above the Devine estimate over several years, with normal blood work and good fitness, is less concerning than a rapid 5 kg gain in six months that places you within the formula estimate but masks deteriorating health.
Medical disclaimer: This calculator provides estimates based on population-level formulas and is for informational and educational purposes. It is not a substitute for professional medical advice. Ideal weight formulas should not be used as the sole basis for medication dosing, dietary planning, or weight management decisions without consultation with a qualified healthcare provider. Do not disregard professional medical advice or delay seeking it based on the results of this calculator.
Do not use ideal weight as the sole measure of weight-related health. Body composition matters more than body weight. A person at their ideal weight but with high body fat percentage and low muscle mass has a higher health risk than a person 5 kg above their ideal weight with low body fat and high muscle mass. If you are active and muscular, expect your healthy weight to be above the formula estimates. If you are sedentary with low muscle mass, your healthy weight may be below the estimates. The BMI range gives you a wider target zone that is more forgiving of individual variation than a single formula estimate.
Trends matter more than a single measurement. Tracking your weight over time and noting whether it is moving toward or away from your healthy weight range is more informative than comparing a single reading to a formula. A gradual increase from 2 kg below your ideal estimate to 5 kg above it over two years signals a trend that warrants attention, even if each individual reading is within the healthy BMI range. Conversely, a stable weight that is 3 kg above the Devine estimate over several years, with normal blood work and good fitness, is less concerning than a rapid 5 kg gain in six months that places you within the formula estimate but masks deteriorating health.
Medical disclaimer: This calculator provides estimates based on population-level formulas and is for informational and educational purposes. It is not a substitute for professional medical advice. Ideal weight formulas should not be used as the sole basis for medication dosing, dietary planning, or weight management decisions without consultation with a qualified healthcare provider. Do not disregard professional medical advice or delay seeking it based on the results of this calculator.
Ideal Weight vs. BMI vs. Body Fat Percentage
Ideal weight and BMI measure different aspects of weight status. Ideal weight estimates a single target weight for your height and sex using formulas designed for medication dosing and clinical reference. BMI assesses your current weight relative to your height and categorises you into underweight, normal, overweight, or obese. The two systems can give apparently conflicting signals. A person with a Devine estimate of 68 kg who currently weighs 75 kg has a BMI of 25.9 (overweight) for a height of 170 cm, but the ideal weight estimate is closer to their current weight than the BMI cutoff. This does not mean either system is wrong; it means they serve different purposes and should be used together.
Body fat percentage resolves the ambiguity that both ideal weight and BMI leave open. A person can be at their ideal weight with high body fat (normal-weight obesity) or well above their ideal weight with low body fat (muscular athlete). Only body fat measurement distinguishes these scenarios. The US Navy circumference method, available in the Body Fat Percentage Calculator on this site, estimates body composition using waist, neck, and hip measurements. Combining your ideal weight estimate with body fat percentage gives you a complete picture: the weight target tells you the number, and the body fat percentage tells you what that number is made of.
Body fat percentage resolves the ambiguity that both ideal weight and BMI leave open. A person can be at their ideal weight with high body fat (normal-weight obesity) or well above their ideal weight with low body fat (muscular athlete). Only body fat measurement distinguishes these scenarios. The US Navy circumference method, available in the Body Fat Percentage Calculator on this site, estimates body composition using waist, neck, and hip measurements. Combining your ideal weight estimate with body fat percentage gives you a complete picture: the weight target tells you the number, and the body fat percentage tells you what that number is made of.
Medical disclaimer
This calculator provides ideal weight estimates for informational and educational purposes only. It is not a medical device and is not a substitute for professional medical advice, diagnosis, or treatment. Healthy weight ranges vary based on individual body composition, bone density, and muscle mass. Consult a qualified healthcare provider for personalised health recommendations.
For further reading, explore related health assessment tools on ToolsArena. The BMI Calculator uses your current weight and height to determine your body mass index and WHO weight category. The BMR Calculator tells you your basal metabolic rate for designing a calorie-controlled diet. The Daily Calorie Needs Calculator estimates your total daily energy expenditure for weight management planning.
Summary
Your ideal body weight is estimated using the Devine and Robinson formulas, both of which calculate a weight target based on your height and biological sex. The Devine formula (1974) was developed for medication dosing and is the clinical standard for weight-based drug calculations. The Robinson formula (1983) was derived from national health survey data and provides a slightly different estimate. Your healthy BMI range shows the weight interval associated with the lowest all-cause mortality at the population level. Together, these four reference points give you a complete picture of the weight ranges that medical professionals use for different purposes. Use the visual scale and bar chart to compare the estimates at a glance, and combine this information with body composition, waist circumference, and blood work for a complete health assessment.
Published:
Updated:
References
- [1]NHLBI, National Heart, Lung, and Blood Institute - BMI Calculator. https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm
- [2]National Institutes of Health, National Heart, Lung, and Blood Institute - Assessing Your Weight and Health Risk. https://www.nhlbi.nih.gov/health/educational/lose_wt/risk.htm
- [3]Drug Intelligence Publications, Devine BJ - Gentamicin Therapy. Drug Intelligence & Clinical Pharmacy, 1974. https://pubmed.ncbi.nlm.nih.gov/4606809
Glossary
- Ideal body weight – An estimate of the weight associated with the lowest health risk for a given height and biological sex, used primarily for medication dosing and clinical reference.
- Devine formula – A formula developed in 1974 by Dr. Bernard Devine for calculating ideal body weight, originally for theophylline dosing. Uses 50 kg base for men and 45.5 kg for women at 5 feet, adding 2.3 kg per inch above 5 feet.
- Robinson formula – A formula published in 1983 derived from NHANES I survey data. Uses 52 kg base for men and 49 kg for women at 5 feet, adding 1.9 kg per inch for men and 1.7 kg per inch for women.
- Miller formula – A formula published in 1983 that uses a smaller per-inch increment than Devine and Robinson, giving lower estimates for taller individuals. Base weights of 56.2 kg for men and 53.1 kg for women.
- Hamwi formula – A formula developed in 1964 for dietetics reference, using a larger per-inch increment. Base weights of 48 kg for men and 45.5 kg for women, adding 2.7 kg per inch for men and 2.2 kg per inch for women.
- Body Mass Index (BMI) – A measure of body fat based on height and weight, calculated as weight in kilograms divided by height in metres squared. WHO classifies BMI below 18.5 as underweight, 18.5 to 24.9 as normal, and 25.0 and above as overweight.
- Healthy weight range – The weight range corresponding to a BMI of 18.5 to 24.9, as defined by the WHO. Unlike ideal weight formulas, this is a range rather than a single number.
- Frame size – An individual's bone structure size, typically classified as small, medium, or large. Frame size affects the relationship between height and healthy weight but is not accounted for in standard ideal weight formulas.
- Lean body mass – The total mass of the body minus body fat, consisting of muscle, bone, organs, and water. Ideal weight formulas aim to estimate lean body mass range for medication dosing purposes.
- Adjusted body weight – A modified weight used for obese patients in clinical dosing, calculated as ideal body weight plus a fraction of the excess weight. Commonly used when actual weight exceeds ideal weight by more than 20 percent.
How to Use?
- 1.
Enter your height: Type your height into the height field. Use the unit dropdown to switch between centimetres (cm), feet (ft), or inches (in). The calculator converts to centimetres automatically.
- 2.
Select your biological sex: Choose male or female from the dropdown. The Devine and Robinson formulas use different base weights and increments for each sex.
- 3.
Review your ideal weight estimates: The calculator displays the Devine formula estimate, Robinson formula estimate, and healthy BMI minimum and maximum. Switch between kilograms, pounds, and stone using the unit dropdown on any result.
- 4.
Compare the estimates on the visual scale: The coloured BMI scale shows where the Devine formula estimate falls relative to the WHO classification categories. The bar chart below the estimates compares all four values side by side for quick visual comparison.
- 5.
Use the estimates as a reference range: Your personal healthy weight is likely somewhere between the Devine and Robinson estimates and within the BMI range. Do not fixate on a single number. Combine these estimates with body composition, waist circumference, and blood work for a complete health picture.
Frequently Asked Questions
Ideal body weight (IBW) is an estimate of the weight that is associated with the lowest health risk for a given height and biological sex. It is determined using population-level formulas, the widely used being the Devine and Robinson formulas. Both calculate a base weight for a height of 5 feet (152.4 cm) and add a fixed amount per inch above that height. The Devine formula adds 2.3 kg per inch for both sexes, while the Robinson formula adds 1.9 kg per inch for men and 1.7 kg per inch for women. These estimates are reference points for clinicians, not precise individual targets.
The Devine formula calculates ideal weight as 50 kg for men at 5 feet plus 2.3 kg per inch above 5 feet, and 45.5 kg for women at 5 feet plus 2.3 kg per inch above 5 feet. It was published in 1974 by Dr. Bernard Devine for calculating theophylline doses in respiratory medicine. It has since become a widely used ideal weight formula in clinical practice, particularly for medication dosing in anaesthesia, critical care, and chemotherapy. The formula is simple but was never validated for general health assessment, which is why it should be used alongside the healthy BMI range.
The Robinson formula calculates ideal weight as 52 kg for men at 5 feet plus 1.9 kg per inch above 5 feet, and 49 kg for women at 5 feet plus 1.7 kg per inch above 5 feet. It was published in 1983 by Dr. Robinson and colleagues using data from the first National Health and Nutrition Examination Survey (NHANES I). Because the formula was derived from a nationally representative sample, it is often preferred in nutrition research and dietetics. The Robinson formula tends to give higher estimates for shorter individuals and lower estimates for taller individuals compared to the Devine formula.
Neither formula is definitively more accurate because both are population-level estimates with substantial individual variation. The Devine formula is the clinical standard for medication dosing and is recommended by major anaesthesia and critical care guidelines. The Robinson formula is more commonly used in nutrition research because it was derived from a representative population survey. In practice, the two formulas typically produce estimates within 2 to 5 kg of each other, and the true healthy weight for an individual depends on muscle mass, bone density, frame size, and overall body composition. The most useful approach is to use the range between the two estimates as your target zone.
Ideal weight is a single number produced by a formula such as Devine or Robinson. Healthy weight is the entire weight range corresponding to a BMI of 18.5 to 24.9, as defined by the WHO. A person with a height of 170 cm has a healthy weight range of 53.5 to 72.0 kg, while their Devine estimate (for a male) is 66.5 kg. The two concepts serve different purposes: ideal weight formulas give a clinical reference point for dosing and screening, while the healthy BMI range gives a wider target zone associated with the lowest population-level mortality. For personal weight goals, the healthy BMI range is more useful because it accounts for individual variation.
Yes, ideal weight estimates can serve as reference points for setting realistic weight loss or gain targets, but they should not be the sole determinant. A reasonable approach is to aim for a weight within the healthy BMI range, using the ideal formula estimates as rough guidelines. If your current weight is above the healthy BMI maximum, set an initial goal of reaching the upper end of the range, then reassess. Always combine weight targets with body composition assessment. Losing weight while preserving muscle mass is more important than reaching a specific number on the scale.
No, ideal weight formulas do not account for muscle mass, bone density, or body composition. They use only height and biological sex to produce an estimate. This is their most significant limitation. A muscular athlete and a sedentary person of the same height and sex receive the same ideal weight estimate, even though muscular individuals typically weigh more and have healthier body composition. If you are physically active and have significant muscle mass, your healthy weight may be 5 to 15 kg above the formula estimate. Body fat percentage measured by skinfold calipers or bioelectrical impedance provides a more accurate assessment.
The standard Devine and Robinson formulas do not include ethnicity adjustments, and no widely accepted ethnicity-specific versions exist. Research suggests that the relationship between height, muscle mass, and body fat varies across ethnic groups, which may affect the accuracy of ideal weight estimates. People of Asian descent tend to have higher body fat percentages at the same BMI and may have lower optimal weights than the formula estimates. People of African descent may have higher bone density and muscle mass, potentially making the formula estimates conservative. The healthy BMI range provides a more flexible target zone that partially addresses these differences, but individuals should discuss personalised weight targets with their healthcare provider.
Ideal weight formulas are less applicable to athletes and bodybuilders because these individuals have significantly more muscle mass than the general population. A male bodybuilder with a height of 180 cm may weigh 90 to 100 kg with very low body fat, which is well above his Devine estimate of 69.8 kg. This does not mean he is overweight; it means the formula does not account for his muscle mass. Athletes should use body fat percentage as their primary body composition metric rather than weight-based formulas. The ideal weight estimates on this page are provided as general reference only and should not be used as health targets for highly muscular individuals.
The Devine and Robinson formulas were developed for general adult populations and may be less appropriate for older adults. After age 30, adults lose 3 to 8% of their muscle mass per decade, which changes body composition even if weight remains stable. A 75-year-old who achieves the same weight as their 30-year-old ideal estimate may have more body fat and less muscle than is healthy. Some geriatric guidelines recommend a slightly higher BMI target of 24 to 27 for adults over 65, as a modest amount of body fat provides metabolic reserve during illness and a slightly higher weight correlates with better outcomes. Older users should discuss weight targets with a healthcare provider who can assess their individual muscle mass and functional status.
Stand against a wall with your heels, buttocks, and shoulders touching the surface. Remove your shoes. Look straight ahead so your line of sight is horizontal. Place a flat object such as a book or ruler on top of your head, perpendicular to the wall. Mark the wall at the bottom edge of the object. Measure from the floor to the mark using a tape measure. Record your height to the nearest 0.1 cm or 0.1 inch. Do not estimate your height by looking down at a tape measure, as this introduces parallax error of 1 to 3 cm.
No, the formulas use different base weights and per-inch increments for men and women. For the Devine formula, men start at 50 kg at 5 feet and women start at 45.5 kg. The per-inch increment of 2.3 kg is the same for both sexes. For the Robinson formula, men start at 52 kg with an increment of 1.9 kg per inch, while women start at 49 kg with an increment of 1.7 kg per inch. These differences reflect average differences in body composition, muscle mass, and fat distribution between sexes. At the same height, the male estimate is always higher than the female estimate, typically by 4 to 8 kg depending on the formula.
Ideal weight estimates do not change unless your height changes, which is rare in adults. You only need to recalculate if you want to see the estimates in a different unit or if your height changes due to conditions such as spinal compression from aging, scoliosis, or vertebral fractures. The more useful practice is to track your actual body weight relative to the healthy BMI range over time. Checking your weight once per month and comparing it to your target range gives you a meaningful trend. A gradual drift toward the upper end of the range signals the need for preventive action, while a stable weight within the range confirms that you are maintaining a healthy weight.
Your ideal weight estimate does not change unless your height changes because the formulas use only height and biological sex. However, your personal optimal weight can and should change as you age. As muscle mass declines and body composition shifts, the weight that is healthiest for you may differ from the formula estimate. For example, an active 30-year-old may thrive at 3 kg above their Devine estimate because they carry significant muscle mass, while the same person at 70 with reduced muscle mass may be healthier 2 kg below their Devine estimate. The static nature of the formulas is a limitation, which is why they should be treated as reference points rather than targets.
Yes, discussing weight targets with a healthcare provider is recommended, especially if you have underlying health conditions, are taking medications, or are planning significant weight changes. A doctor can assess your individual risk factors, review your blood work, measure your waist circumference and body fat, and help you set a personalised weight target that accounts for your muscle mass, bone density, medical history, and lifestyle. This calculator provides population-level estimates that are useful for general reference but should not replace personalised medical advice. Always consult a qualified healthcare provider before starting a weight management programme.
Related Calculators
Explore All 11 Health CalculatorsBrowse by Category
Browse All 9 CategoriesShare: