Category: Date & time
Date Add/Subtract Calculator
Add or subtract days, weeks, months or years from a date
Pick a start date, an amount, and a unit — days, weeks, months or years — to add or subtract, and see the resulting calendar date. Runs entirely in your browser.
Result dateSaturday, January 31, 2026
Everything on this page is processed in your browser. Nothing is uploaded.
What this tool does
This tool shifts a calendar date by a whole number of days, weeks, months or years. Month and year arithmetic follows normal calendar rollover, so adding 1 month to January 31 lands on March 3 rather than a clamped February date, the same behavior most calendar libraries use.
How to use it
- Pick a start date.
- Enter an amount and choose whether to add or subtract it.
- Choose a unit — days, weeks, months or years — to see the resulting date.
Privacy
This tool runs entirely in your browser. Your input is never uploaded, stored or shared — closing the tab removes it.
Frequently asked questions
- How does adding a month to the 31st of a month work?
- Month arithmetic follows normal calendar rollover: adding 1 month to January 31 lands on March 3, since February does not have 31 days.
- Does this account for time zones?
- No. It works with calendar dates only, in UTC, so the result does not depend on your local time zone.
- Can I subtract a large number of years?
- Yes. Any whole number of days, weeks, months or years is supported, including moving to a different century.