Add days calculator
Add or subtract a whole number of calendar days from a date. Leap years and month boundaries are handled automatically.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Starting date | Use the stated Gregorian calendar date format. A calendar date is not a timezone-specific timestamp. |
| Days to add or subtract | Enter days to add or subtract using the definition in the method and example. |
Understanding your result
Calendar results use the stated counting and anniversary convention. Complete months and years differ from fixed day counts.
Common mistakes
- Counting both end dates when the method excludes a boundary, or assuming all months have equal length.
Check your calculation
- Test a short known interval and a leap-day boundary; for working days, verify your holiday list.
Calculation checks, sources and review limits
What date will it be after adding or subtracting this many days?
Enter a starting date and a signed whole-day offset. Positive values move forward; negative values move backward. Weekends and holidays are counted.
Common uses
- Find a date a fixed number of days from now.
- Work backwards from a date by a calendar-day interval.
How it works
A positive offset moves forward; a negative offset moves backward. The starting date is day zero. Weekends and holidays count as ordinary calendar days. The date uses the Gregorian calendar and is not shifted by your device’s timezone.
Worked example
Adding 2 days to 28 February 2024 gives 1 March 2024. Subtracting 1 day from 1 January gives 31 December of the previous year.