Date Add / Subtract Calculator
Move a date forward or backward by a chosen calendar interval and see the resulting day of the week.
Result date2026-10-06
Day of weekTuesday
How this tool works
Days and weeks use calendar-day increments. Months and years use calendar month/year arithmetic so month length and leap years are handled by the date engine.
Example
Add 90 days to a contract date, or subtract six months from a renewal deadline.
Common questions
Is adding one month the same as adding 30 days?
No. Calendar months have different lengths, so month arithmetic and day arithmetic can produce different dates.
Are dates shifted by my local time zone?
Date-only inputs are handled as UTC calendar dates to avoid a browser time-zone offset changing the day.