Browser-onlyLiveGeneral Calculators
Date Calculator
Add or subtract days, weeks, or months from a date.
Privacy note. Runs in your browser. The base date and offset you choose never leave this page.
Result date2000-01-31
Day of weekMonday
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Frequently asked questions
YYYY-MM-DD (ISO 8601), for example 2026-05-31. Anything else will show a validation message instead of a result.
When adding months or years would push the day beyond the end of the target month, the result clamps to the last day of that month. So Jan 31 + 1 month resolves to Feb 28 (or Feb 29 on leap years).
Use the Subtract direction with a positive amount instead. The result still clamps the day-of-month when needed.
Last updated 2026-06-03.