Date calculator: add or subtract days
A date plus or minus days, weeks, months or years
Start from any date and move forward or back. The example shows the date 90 days from today.
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- Distance from start
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- Day of the week
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- Written as YYYY-MM-DD
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How the date is worked out
Pick a start date, choose add or subtract, and fill in any mix of years, months, weeks and days. Boxes left at 0 are ignored. Years and months are applied first, then weeks and days. The order matters near a month end: 31 Jan 2026 plus 1 month and 1 day is 28 Feb and then 1 Mar.
Month ends are clamped
Adding one month to 31 Jan 2026 gives 28 Feb 2026, because there is no 31 February. In a leap year such as 2024 it gives 29 Feb. In the same way 31 Aug plus 1 month is 30 Sep. The result never spills into the following month, and the result card tells you whenever this adjustment was made. One side effect: adding a month and then taking it away does not always bring you back. 31 Mar minus 1 month is 28 Feb, and 28 Feb plus 1 month is 28 Mar.
Years, weeks and days
Adding years to 29 Feb lands on 28 Feb when the target year is not a leap year. Weeks are always exactly 7 days and days are exact, so 90 days from a date is usually not the same day as 3 months from it.
Deadlines
For a legal or contract deadline, check the rules that apply: whether the starting day counts, and what happens if the last day falls on a weekend or holiday. This page works on calendar dates only, so daylight saving changes have no effect.