Date & Time Add or Subtract Calculator
Add or subtract years, months, weeks, days, hours, minutes and seconds from any starting date and time.
Enter a starting date/time and an amount to add or subtract.
How date and time addition works
This calculator applies calendar years and months first, then weeks, days, hours, minutes and seconds. Calendar months are handled as real calendar months rather than assuming every month has the same number of days.
Examples
- Add 3 days and 5 hours to a date/time.
- Subtract 2 weeks from a deadline.
- Add 1 year, 2 months and 30 minutes.
- Subtract 90 minutes from a scheduled time.
Calendar arithmetic
Adding a month is not the same as adding a fixed number of days. For example, moving forward one calendar month from January uses the next calendar month, while the exact number of elapsed days depends on the dates involved.