Add or subtract dates
This tool moves a date forward or backward by a number of days, weeks, months or years. It answers questions like "What date is 90 days from today?" or "When is six months after my start date?" Students, planners and office staff use it for due dates and renewals.
- Runs in your browser
- Free, no account needed
- Copy or download the result
Result
Example
2024-01-31
Result: 2024-02-29 Months and years clamp to the last valid day. Days and weeks add calendar days.
How to use the add or subtract dates
- Type the starting date as YYYY-MM-DD, such as 2024-01-31.
- Enter a whole number in Amount, negative to subtract. Use -10 to go back 10 units.
- Choose days, weeks, months or years in Calendar unit.
- Press Run, then Copy result or Download.
How it works
The Amount must be a whole number from -1,000,000 to 1,000,000.
Days and weeks add plain calendar days, with one week counted as 7 days.
Months and years keep the same day of the month when it exists. If it does not, the result moves to the last valid day, so 2024-01-31 plus 1 month is 2024-02-29.
Weekends and holidays are not skipped.
The result must stay in years 0001 to 9999, or you get an error.
Everything runs in your browser. Your input is not uploaded or stored.
Questions and answers
What is one month after January 31?
There is no February 31, so the tool uses the last day of February. In 2024 that is February 29, and in 2025 it is February 28.
How do I subtract days from a date?
Type a negative number in the Amount field, such as -30, pick days, and press Run.
What happens when I add a year to February 29?
If the next year is not a leap year, the result is February 28 of that year.
Can I add only working days?
Not with this tool, because it counts every calendar day. The business day calculator skips Saturdays and Sundays.