What happens when I add one month to January 31?
With clamp mode, the result becomes the last valid day of February. With roll mode, the overflow carries into the following month.
Date Calculator
Add or subtract calendar time and business days from a start date with clear month-end behavior.
Add or subtract time from a date
The Date Calculator adds or subtracts years, months, weeks, days, and business days from a start date. It shows the result date, weekday, day of year, ISO week, quarter, and how many calendar or business days moved.
Month-end handling is explicit: clamp to the last valid day of the target month, or roll overflow into the next month.
What the date calculator includes
- Add or subtract years, months, weeks, days, and business days.
- Choose how month-end overflow behaves.
- See weekday, day of year, ISO week, and quarter.
- Preview six repeated steps with the same settings.
- Copy a clear summary for records or planning notes.
Loading tool...
Use cases for date addition
Use date addition for invoice terms, renewal reminders, trial periods, follow-ups, project milestones, compliance reviews, warranty periods, and recurring schedules. When a result affects legal or contractual deadlines, verify the governing rule and holiday calendar.
Date calculator FAQ
Do business days skip holidays?
No. Business days skip Saturdays and Sundays only. Add local holidays manually if your workflow requires them.
What is the repeat preview for?
It shows the next six dates if you apply the same date calculation repeatedly, which is useful for recurring reminders and schedules.
