How Add / Subtract Date works

Add or subtract years, months, weeks, days, hours and minutes with predictable calendar-aware month-end behavior.

The formula

Years and months are applied first and clamp to the last valid day, followed by weeks, days, hours and minutes.

A practical example

January 31 plus one month becomes February 28, or February 29 in a leap year.

Important limitations

The tool treats the selected date and time as a floating calendar value, without applying a timezone or daylight-saving transition.

Frequently asked questions

What happens at the end of a month?

If the same day does not exist in the destination month, the result clamps to that month’s final day.

Can I subtract values?

Yes. Choose Subtract and enter positive adjustment values.