Date calculator
Add or subtract days, weeks, months or years from a date, and count the days, weeks and working days between two dates.
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Runs in this page in your browser; nothing is uploaded.
About this tool
Add or subtract days, weeks, months or years from a date, or count the days between two dates. Use it to find the date 100 days from today, a contract’s end date or a due date counted in weeks, or to see how many working days are left before a deadline.
Results update as you type, and a calculated date comes with its weekday. A difference is given in days, in weeks and days, in years, months and days, and in working days from Monday to Friday, without deducting public holidays. Dates are calculated in UTC, so daylight saving never shifts a day. It runs in your browser and nothing is uploaded.
How to use it
- Under “Add or subtract”, pick a “Date”. It starts at today.
- Enter a number in “Add (negative to subtract)”, 100 by default, and choose the “Unit”: days, weeks, months or years. The resulting date and weekday appear below.
- Under “Days between two dates”, set “From” and “To”.
- Read the “Days”, “Weeks”, “Years, months and days” and “Working days (Monday to Friday)” rows.
Common questions
Are the start and end dates both counted?
The count includes the start date and not the end date, so one Monday to the next is 7 days. If you need both days included, add 1 to the result.
What is 31 January plus one month?
When adding months or years lands past the end of a month, the result moves to that month’s last day: 31 January + 1 month is 28 or 29 February, and 29 February + 1 year is 28 February.
Are public holidays left out of the working days?
No. Working days are simply Monday to Friday, counted over the same span as the days (start date included, end date not). Public holidays and make-up working days are not taken into account.
What if the end date is before the start date?
The days, weeks and working days come out negative, while the “Years, months and days” row shows the length of the gap.
How are years, months and days counted?
The page counts the most whole months that fit between the dates, then the days left over. For example, 31 January to 1 March 2024 is 1 month and 1 day, because 31 January + 1 month is 29 February.
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