Date Adder

Add or subtract days, weeks, months, or years from any date — great for deadlines, due dates, and anniversaries.

Start date

Operation

Amount

Unit

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How it works

Days and weeks are simple day counts — 10 days after January 1 is January 11. Months and years use true calendar arithmetic instead: adding one month to March 1 lands on April 1, and adding one year handles leap days correctly. All math runs in UTC so daylight saving transitions can’t shift the result, and the answer includes the weekday so you can spot at a glance whether your deadline falls on a weekend.