Date Add and Subtract Calculator
Add or subtract days, weeks, months, and years from any calendar date.
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The date calculator allows you to add or subtract calendar units from a specified starting date. You can adjust the base date by entering any combination of days, weeks, months, and years. When months or years are adjusted, the calculator shifts the calendar to the target month and year. If the target month has fewer days than the starting date, the day automatically snaps to the final day of that month, such as moving from January 31 to February 28 in a non-leap year. Weeks are converted into seven-day intervals and applied alongside day offsets. After you run the calculation, the tool displays the new calendar date in standard YYYY-MM-DD format along with useful calendar details, including the corresponding day of the week, the day number within the year, and the ISO week number. If an invalid date is entered or the calculation exceeds supported date limits, the tool indicates the issue.
Instructions
- Enter a starting date in YYYY-MM-DD format, or keep the default date.
- Specify the number of days, weeks, months, or years you want to adjust.
- Select whether to add or subtract the specified time intervals.
- Run the calculation to view the calculated calendar date and week information.
Examples
- Add 1 month and 5 days to 2024-01-01 to arrive at 2024-02-06 (Tuesday, day 37 of the year, ISO week 6).
- Subtract 2 weeks and 3 days from 2024-06-15 to calculate 2024-05-29 (Wednesday, day 150 of the year, ISO week 22).
FAQ
What happens when adding a month to January 31 in a non-leap year?
The calculator moves to February and adjusts the day to the last valid day of that month, resulting in February 28.
How does the tool handle week adjustments?
Each week is converted into a 7-day increment and combined with any day values provided.
What date format is accepted?
Dates must be entered in the standard calendar format YYYY-MM-DD.