Find your exact age in years, months and days from your date of birth, plus your age in days, weeks and hours and the days to your next birthday.
Date Difference Calculator
Count days, weeks, months and years between two dates, or add and subtract calendar time from a date.
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Date difference
Total days
Weeks and days
Hours and minutes
Calculated date
Calendar days include weekends and holidays. When a date such as 31 January is moved by one month, the result is clamped to the last day of the target month.
Runs entirely in your browser. Your files and text are not uploaded.
How to use Date Difference Calculator
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Step 1: Choose a calculation
Compare two dates or add and subtract time from one date.
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Step 2: Enter dates
Add optional times when you need an hours-and-minutes difference. Turn on inclusive counting for leave or rental periods that include both dates.
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Step 3: Read the result
See a calendar duration, total elapsed time and the weekday for each date.
Calendar difference and elapsed time
The calendar result reports completed years, months and days. It treats months as calendar months, so their length can vary. The total-days result counts the days between the two dates separately. If you enter times, the tool also shows elapsed hours and minutes.
Enable Include end date when both dates belong in the count, such as a leave period from 1 June through 3 June. That adds one calendar day to the day count. It does not change the calendar years-and-months display.
Adding months and years
Adding a month keeps the day number where possible. When that day does not exist, the result is moved back to the last day of the target month: for example, 31 January plus one month becomes 28 February in a non-leap year. The same clamping rule applies to years and 29 February.
This tool uses the Gregorian calendar and counts every calendar day, including weekends and public holidays. It does not model time zones or daylight-saving changes. Use a working-days calculator when you need to exclude non-working days.
Limitations
- Calendar days include weekends and holidays.
- Months have different lengths; adding a month can clamp a date to the target month’s last day.
- Daylight-saving and time-zone changes are not modelled.
- Only Gregorian-calendar dates from 1900 through 2200 are supported.
Frequently asked questions
Does the calculator include the end date?
Not by default. Turn on Include end date when both the start and end dates should be counted.
How many days are between two dates?
The standard count excludes the starting date and measures the elapsed calendar days. The inclusive option adds the end date to that total.
What happens when I add one month to 31 January?
The result is clamped to the final day of February: 28 February in a non-leap year or 29 February in a leap year.
Related tools
Add or subtract hours, minutes and seconds. Find the difference between two times or add a duration to a start time.
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