Add/Subtract Date
Add or subtract time units from any date.
Examples
| Input | Result |
|---|---|
| 2024-03-01 + 90 days | May 30, 2024 12:00:00 AM |
| 2024-12-25 10:00 - 6 hours | December 25, 2024 4:00:00 AM |
| 2025-01-15 + 3 months | April 15, 2025 12:00:00 AM |
| 2024-07-04 - 2 weeks | June 20, 2024 12:00:00 AM |
About this tool
Pick a starting date and time, choose an amount and a unit (years, months, weeks, days, hours, or minutes), and this tool calculates the resulting date. Use negative values to subtract instead. This comes up often when you need to find a deadline that is "90 days from today," work out an expiration date, or figure out what date falls a certain number of weeks before an event.
Month arithmetic follows the standard convention: adding months advances the month number while keeping the day the same where possible. If the day would overshoot (like adding 1 month to October 31), it clamps to the last valid day of the target month. Results are shown in both a human-readable local format and ISO 8601.
Frequently asked questions
What happens when you add 1 month to January 31?
Adding 1 month to January 31 gives you February 28 (or February 29 in a leap year). When the target month has fewer days than the source date, the result clamps to the last day of that month.
How do I subtract time from a date?
Enter a negative number in the amount field. For example, entering -30 with the unit set to "days" will subtract 30 days from your chosen date.
Does adding weeks account for daylight saving time changes?
Week and day additions simply add the equivalent number of days to the calendar date. If a DST transition occurs within that span, the wall clock time may shift by an hour, but the calendar date will be correct.