How to use the next leap day countdown
Select an as-of date or leave the default set to today to find the next leap day.
How the calculation works
Leap days occur only in leap years. The 400-year rule matters for centuries such as 2100, which will not be a leap year.
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
Does the countdown include today?
If the selected date is 29 February, the countdown shows zero days.
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.