Date Difference Calculator
Pick a start date and an end date below to instantly calculate the difference in days, weeks, and years, months and days.
Pick two dates
How to calculate the difference between two dates
- Pick a start date and an end date using the date pickers.
- The total number of days, weeks, and an approximate number of months update instantly.
- Check the years, months and days breakdown for a calendar-style duration.
Why calculate the days between two dates
Counting the days between two dates comes up in more situations than you'd expect: figuring out how many days remain until a deadline or event, calculating the length of a trip or a rental period, checking how many days a project ran over, or working out someone's exact age in days for a milestone celebration.
FAQ
Is this date difference calculator really free, with no sign-up?+
Yes. The tool runs entirely with JavaScript in your browser — there's no account, no API key, and no limit on how often you can use it.
Does the calculator include both the start and end date in the count?+
The total days figure is the number of full days between the two dates (end date minus start date), not counting either date twice. If you need an inclusive count that adds one extra day, simply add 1 to the total.
How is the years, months and days breakdown calculated?+
It calculates the largest whole number of years between the two dates, then the largest whole number of months from that point, then the remaining days — the same way you'd count age or a duration by hand.
Can I calculate a date that's in the future?+
Yes, if the end date is after the start date the result is a positive countdown-style difference; if it's before, the result shows how far in the past it is.
Does this account for leap years?+
Yes, the calculation is based on actual calendar dates, so leap years are automatically factored into the day count.
Tools for Dates & Calculations
How This Calculator Works
Your dates are compared live using JavaScript's built-in date handling, which automatically accounts for leap years and varying month lengths — nothing you enter is uploaded to a server or stored anywhere.
Last updated: August 28, 2026.
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