How to Calculate Days Between Two Dates
Calculating the number of days between two dates is essential for project planning, contract durations, loan terms, event countdowns, and many other everyday situations. The calculation needs to account for months of varying lengths and leap years, which is why a calculator is more reliable than manual counting.
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Formula
Days Between Dates
Calculate the exact number of days, weeks, and months between any two dates.
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Worked Example
Given:
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FAQs
Why does the result differ by one depending on whether endpoints are included?
Whether you include the start date, end date, both, or neither changes the count by one or two days. This calculator counts the absolute difference between the two dates, not including either endpoint — the same method used in most project management and contract contexts.
How are leap years handled?
Leap years are handled automatically because the calculation works with actual date objects rather than assuming 365 days per year. A full year from January 1 2024 to January 1 2025 correctly returns 366 days because 2024 is a leap year.
Can I calculate days between dates in different years?
Yes — the calculator works for any two dates regardless of how many years apart they are. It will correctly count all days including multiple leap years within the range.