Overview
A leap year is added roughly every four years to keep the Gregorian calendar aligned with the solar cycle. Check any year and see its length plus the nearest leap years.
Formula
Rule: a year is leap when divisible by 4 and not by 100, or when divisible by 400. So 2024 is leap, 2100 is not, and 2400 is leap.
How it works
Enter the year
Type the Gregorian year to check.
Read the verdict
See whether it is leap and how many days it has.
Compare years
The nearest previous and next leap years appear.
Worked examples
2024
Divisible by 4 and not 100, so it is leap with 366 days.
1900
Divisible by 100 but not 400, so it is not a leap year.
Frequently asked questions
Why is 1900 not a leap year?
It is a century year divisible by 100 but not 400.
Is 2000 a leap year?
Yes, because it is divisible by 400.
When is February 29 added?
Only in leap years, and it is included in the year length.
This calculator is for educational and informational purposes only and is not a substitute for professional advice.