Date Duration Calculator
How much time is between two dates? Get the exact duration in years, months, days — plus total days and weeks.
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- Works offline
What Is a Date Duration?
A date duration is the exact span of time between two calendar dates. This calculator expresses it in years, months, and days, and also gives you the total number of days and weeks between them. People use it to measure project lengths, count down to events, calculate tenures, or simply answer "how long has it been?"
How to Use This Calculator
- Enter a start date and an end date.
- Add optional labels (for example "Hire date" and "Today") to make the result clearer.
- Use the swap button to flip the two dates instantly.
- Read the duration in years/months/days and the totals below.
The Formula
The calculator finds the calendar difference between the two dates:
The subtraction "borrows" days from months and months from years — the same method used to compute a person's exact age — so leap years and month-end edges are always correct.
Examples
Click any example to try it:
Frequently Asked Questions
How do you calculate the duration between two dates?
Subtract the earlier date from the later date. The result is shown as years, months, and days using calendar math, plus the total number of days and weeks between them.
Does the order of the two dates matter?
No. The calculator detects which date comes first and always reports a positive duration, regardless of which field you fill in first.
Are leap years handled correctly?
Yes. The math is calendar-aware and correctly handles leap years and months of different lengths, so edge cases like February 29 are always accurate.