Leap Year Checker
Check if any year is a leap year, or list every leap year in a range.
How to Check a Leap Year
- Enter any year to instantly see if it's a leap year.
- Enter a start and end year to list every leap year in that range.
Frequently Asked Questions
What is the exact rule for a leap year?
A year is a leap year if it's divisible by 4, unless it's also divisible by 100 — in which case it's only a leap year if it's also divisible by 400. This is why 2000 was a leap year but 1900 and 2100 are not, even though all three are divisible by 4.
Why do we need leap years at all?
Earth's orbit around the sun takes about 365.2422 days, not exactly 365. Adding a leap day roughly every 4 years keeps the calendar synced with the seasons; the extra 100/400-year exceptions correct for that 365.2422 figure being slightly less than 365.25, so leap years aren't added quite as often as a simple "every 4 years" rule would suggest.
How many days are in February during a leap year?
29 days instead of the usual 28 — that extra day, February 29th, is the leap day itself.
Is my data sent anywhere?
No — the check runs entirely in your browser using JavaScript, so nothing you enter is ever sent to a server.