Time
Add or Subtract Time From a Date
Move a date-time forward or backward by years, months, weeks, days, hours, minutes, or seconds.
Add or Subtract Time From a Date result
- ISO date
- 2026-10-17
- Weekday
- Saturday
- ISO week / week-year
- 2026-W42
- Day of year
- 290
- Calendar quarter
- Q4
Months and years clamp to the last valid day when necessary. Clock time uses this device’s local zone; daylight-saving changes can alter elapsed hours.
Save or exportOptional
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How this tool works
Years and months are applied with end-of-month clamping, followed by weeks, days, hours, minutes, and seconds. In business-day mode, the Days field advances through the shared weekend and closure engine.
Assumptions
Calendar years and months are applied before weeks, days, and clock units. Missing destination dates clamp to the final valid day; optional business-day mode applies only to the Days field and skips selected closures.
Limits to know
Calendar month and year addition clamps invalid destination dates, such as January 31 plus one month. Business-day mode applies only to the Days field and knows only the selected weekends and closures. Daylight-saving transitions can change elapsed hours even when calendar fields are correct.