Calculate / Free tool
Calculate a past date
Subtract days, weeks, months or years from a reference date.
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How it works
The calculation subtracts a calendar duration. For months and years, the target date keeps the original day when it exists; otherwise, it uses the last day of the month. Subtracting one month is therefore not always the same as subtracting 30 days.
March 31, 2025 − 1 month = February 28, 2025
Does adding and then subtracting months always return the original date?
No. January 31 + 1 month gives February 28, then − 1 month gives January 28. Moving to a shorter month changed the day.