Date & time
Add or Subtract Dates
Move a date forward or backward by days, weeks or calendar months.
Runs in your browser · No file or text uploads
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What Add or Subtract Dates helps you do
Find a deadline a few weeks away or the corresponding date in another month. If the target month has no matching day, the result uses its last day.
How to use it
- Choose a starting date.
- Enter a whole number and choose days, weeks or months. Use a negative number to subtract.
- Calculate and check the resulting date and month-end rule.
Input and output example
INPUT
2026-01-31 + 1 calendar monthOUTPUT
2026-02-28
Supported formats and limits
- Month offsets are limited to ±12,000; day and week input values to ±365,250.
- Repeated month-end adjustments may not return to the original day. Results must stay within years 0100–9999.
How the result is calculated
Dates are compared as UTC calendar dates, independently of time zones. A daylight-saving transition still counts as one calendar day. One week is 7 days. Month arithmetic selects the target year and month, then clamps the original day to the last valid day.
Frequently asked questions
Is one month the same as 30 days?
No. A month moves to the actual calendar month. Select days when you need exactly 30 days.