How to use the add or subtract months
Pick your starting date, then enter positive months to add or negative months to subtract.
How the calculation works
If the destination month does not contain the original day, the result uses its final day. For example, 31 January plus one month becomes 28 or 29 February.
Check your inputs carefully: an incorrect date can change a result. Dates and times are entered using your device settings, and no account is needed. For formal, legal, medical or financial purposes, verify the applicable local rules and official records.
Frequently asked questions
What happens to January 31 plus one month?
It becomes the final day of February, depending on whether the year is a leap year.
Which time zone is used?
Dates use your device’s local calendar day. Date-only calculations avoid daylight-saving day-length errors.
Are the dates I enter uploaded?
No. AgeGlide calculates your results in your browser. Entered dates are not sent to our server for processing.