General
Date Calculator
Add or subtract days, weeks or months from a date to find a deadline or start date.
Result
Months are added by calendar, not by 30-day blocks. Adding one month to 31 January gives 3 March in a non-leap year, because February has no 31st: the standard behaviour for date arithmetic.
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About this calculator
How do I find a deadline 90 days out?
Enter the start date, leave the direction on add, and put 90 in the days field. The weekday is shown too, which matters when the deadline lands on a weekend.
Why did adding a month skip a date?
Calendar months have different lengths. Adding one month to the 31st of a month that is followed by a shorter one rolls into the next month.
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