Weight Converter
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By Dr. James WuReviewed by Dr. Andrew Blake, PhD (Materials Science)Published: Updated:
References
- [1]Bureau International des Poids et Mesures (BIPM), The International System of Units (SI) - 9th Edition, 2019. https://www.bipm.org/en/publications/si-brochure
- [2]National Institute of Standards and Technology (NIST), NIST Guide for the Use of the International System of Units (SI), 2008. https://physics.nist.gov/cuu/pdf/sp811.pdf
- [3]International Organization for Standardization (ISO), ISO 80000-4: Quantities and Units - Part 4: Mechanics, 2019.
How to Use?
- 1
Enter the weight value
Type the numeric value you want to convert into the Value field.
- 2
Select the source unit
Choose the unit of your input value from the unit dropdown: mg, g, kg, t, oz, lb, st, US ton, or UK ton.
- 3
Choose the display unit
Use the Display Result In dropdown to select which unit appears highlighted as the primary result.
- 4
Review the result
The result panel shows your value in the chosen display unit, with all other supported units listed as alternatives below it.
- 5
Cross-check key conversions
Use the reference table to verify common factors: 1 kg = 2.205 lb, 1 lb = 454 g, 1 st = 6.35 kg.
- 6
Explore related converters
Use the volume, length, or pressure converters linked on this page for additional unit conversion needs.
Worked Examples
1Convert 1 kilogram to pounds
Given Values
weightValue:1
weightValue_unit:kg
Results
kg:1
2Convert 150 pounds to kilograms
Given Values
weightValue:150
weightValue_unit:lb
Results
kg:68.039
3Convert 500 grams to ounces
Given Values
weightValue:500
weightValue_unit:g
Results
kg:0.5
4Convert 10 stones to kilograms
Given Values
weightValue:10
weightValue_unit:st
Results
kg:63.503
5Convert 1 tonne to pounds
Given Values
weightValue:1
weightValue_unit:t
Results
kg:1000
6Convert 50 milligrams to grams
Given Values
weightValue:50
weightValue_unit:mg
Results
kg:0.00005
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Frequently Asked Questions
Yes, this converter supports all nine units: milligrams (mg), grams (g), kilograms (kg), tonnes (t), ounces (oz), pounds (lb), stones (st), US short tons, and UK long tons. Select your source unit from the dropdown and the tool displays all equivalents instantly.
Conversions are based on internationally accepted values defined by the International System of Units (SI). The pound is defined as exactly 0.45359237 kg by the 1959 International Yard and Pound Agreement. Results are displayed with up to four decimal places for the primary result and appropriate precision for all alternative units.
One pound equals exactly 453.59237 grams by international agreement. For quick mental estimation, 1 lb ≈ 454 g is a common approximation, but for precise work use the full factor. The converter applies the exact factor internally and rounds only at display time.
A stone is a unit of mass equal to 14 pounds (6.35029 kg). It is primarily used in the United Kingdom and Ireland for measuring body weight. A person weighing 12 stone is approximately 76.2 kg. The stone is rarely used in the United States or continental Europe for any measurement.
One avoirdupois ounce equals 28.349523125 grams. To convert ounces to grams, multiply by 28.35. For cooking, 1 oz ≈ 28 g is a common approximation. Note that troy ounces (31.1035 g) are used for precious metals and are different from the avoirdupois ounces used in this converter.
A metric tonne equals 1,000 kg (2,204.62 lb). A US short ton equals 2,000 lb (907.185 kg). A UK long ton equals 2,240 lb (1,016.05 kg). The short ton is about 9.3% lighter than the long ton, and the metric tonne falls between them. This converter includes all three to avoid ambiguity in industrial and commercial applications.
One stone equals 6.35029 kg. To convert stones to kilograms, multiply by 6.35. For example, 12 stone × 6.35 = 76.2 kg. To convert stones and pounds, first convert the pounds to a decimal fraction of a stone (divide by 14), add to the stones, then multiply by 6.35. This converter handles the calculation instantly.
Most countries mandate metric units (grams) for food labelling by law. In the United States, the FDA requires Nutrition Facts labels to show serving sizes in both grams and ounces, but grams are the primary unit. The European Union requires grams and millilitres. This dual-labelling exists because consumers in each country are familiar with their local measurement system for food quantities.
One gram equals exactly 1,000 milligrams. This is a core relationship of the metric mass system. To convert grams to milligrams, multiply by 1,000. To convert milligrams to grams, divide by 1,000. The same relationship applies between kilograms and grams: 1 kg = 1,000 g.
One pound contains exactly 16 avoirdupois ounces. Each ounce equals 28.3495 grams, so 1 lb = 16 × 28.3495 g = 453.592 g. This 16-ounce-per-pound relationship is the same in both the US customary and UK Imperial systems for everyday weight measurements.
Mass measures the amount of matter in an object and is constant regardless of location. Weight measures the gravitational force on that mass and varies with gravity. An object with a mass of 10 kg weighs about 98 N on Earth and about 16 N on the Moon, but its mass is 10 kg in both places. This converter works with mass values, not weight force. For everyday purposes on Earth, the distinction is rarely significant, but it matters in aerospace and high-precision science.
To convert stones and pounds to kilograms: multiply the stones by 6.35029, convert the extra pounds to kilograms (divide by 2.20462), and add the two results. For example, 11 stone 8 lb: (11 × 6.35029) + (8 ÷ 2.20462) = 69.85 + 3.63 = 73.48 kg. To convert kilograms to stones and pounds: multiply by 0.15747 to get the decimal stone value, take the whole number as stones, multiply the decimal part by 14 to get the remaining pounds.
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