Date Calculator
Add or subtract any span from a date. Months and years move the calendar rather than adding a fixed number of days, which is what a deadline or a lease actually means.
How the math works
Years and months are added to the calendar fields, then the day is clamped to the last day of the target month. That is why one month after January 31 is February 28, not March 3. Weeks and days are added afterwards as a plain number of days, in UTC so that daylight saving cannot shift the answer.
Common questions
- What is one month after January 31?
- February 28, or February 29 in a leap year. There is no February 31, so the date is clamped to the end of the month. Nearly every legal definition of "one month" works this way.
- How do I subtract instead?
- Switch the direction dropdown to subtract. Alternatively, enter negative numbers in the fields, which has the same effect.
- What is 90 days from today?
- Set the months to zero and the days to 90 and it is shown above, with the weekday - which matters, because a deadline landing on a Saturday usually moves to the Monday.
- Is 90 days the same as 3 months?
- Almost never. Three months is between 89 and 92 days depending on which months they are. If a contract says 90 days, count days; if it says three months, count months.