Add or Subtract Days
Add or subtract years, months, weeks, and days. Month ends clamp (31 Jan + 1 month is 28 or 29 Feb).
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How to use Add or Subtract Days
- Choose direction first so the fields that apply to that job appear.
- Enter start date, years, months. Leave a field blank only when the page says the value is missing.
- Read the result rows under the form. Errors appear in the status line. Nothing is uploaded.
- Use today fills the as-of or start date using this browser’s local calendar.
Add or Subtract Days
Clamp month-end
| Computes | Add or subtract years, months, weeks, and days. Month ends clamp (31 Jan + 1 month is 28 or 29 Feb). |
|---|---|
| Includes | Clamp month-end |
| Includes | ISO week |
| Engine | dateDiff |
| Upload | None |
| Advice | Arithmetic only |
What Add or Subtract Days is
Civil calendar arithmetic, not a multiple of 24 hours across DST. Weeks are 7 days. The result weekday and ISO week are listed.
The formula runs in this tab. CZNull does not receive the numbers.
How this page computes
Day counts between two known dates are date difference. Business days skip weekends.
Entities and related jobs
Add or subtract years, months, weeks, and days. Month ends clamp (31 Jan + 1 month is 28 or 29 Feb). Named features: Clamp month-end, ISO week.
See also Date Difference Calculator, Business Days Calculator, Date Countdown, Week Number Calculator, Age Calculator, Timesheet Calculator.
Use cases
Deadlines, warranty windows, and 'what date is 90 days from now.'
Limits
Invalid input appears in the status line. IEEE floating point applies unless a row says otherwise. CZNull does not receive the numbers.