Date Add or Subtract Calculator
Pick a start date, choose add or subtract, then enter any mix of years, months, weeks and days. The calculator returns the exact result date and the weekday it falls on.
How to add or subtract time from a date
- Choose your start date.
- Toggle add or subtract and enter the years, months, weeks and days.
- Read the result date and its weekday below.
Examples
Add one month to a month end
2024-01-31, add 1 month
2024-02-29
Subtract two weeks
2024-03-15, subtract 2 weeks
2024-03-01
Frequently asked questions
How does month and year math handle the end of the month?
Years and months are applied first using calendar logic. If the start day does not exist in the target month, the result is clamped to that month's last day. For example, January 31 plus one month becomes February 28, or February 29 in a leap year.
What is the difference between adding and subtracting?
Adding moves the date forward in time, subtracting moves it backward. The same fields are used for both; the toggle simply flips the sign of every value you enter.
How are weeks and days counted?
Weeks and days are exact, so each week is seven days. They are applied after the year and month math, which is why a combined offset is always predictable.
Does this count business days or skip weekends?
No. This tool counts every calendar day, including weekends and holidays. If you need to skip weekends and holidays, use the business days calculator instead.
What order are the offsets applied in?
Years and months are combined and applied first so month overflow and end-of-month clamping resolve correctly, then weeks and days are added as a flat number of days.
Is my date sent to a server?
No. The calculation runs entirely in your browser, so the dates you enter never leave your device.
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