Leap Year Calculator
Check whether any year is a leap year, see exactly why, and get the next three leap years.
How it works
leap year = divisible by 4, except century years, unless divisible by 400
A year is a leap year when it is divisible by 4 — unless it is a century year like 1900, which must also be divisible by 400 to qualify. The rules exist because Earth’s year is about 365.2425 days: adding February 29 every fourth year overshoots slightly, so three century leap days are skipped every 400 years to keep the calendar locked to the seasons.
Worked example
2024 is a leap year: divisible by 4 and not a century. 1900 was not — divisible by 100 but not by 400 — while 2000 was, thanks to the 400 rule. After 2024, the next leap years are 2028, 2032 and 2036.
Frequently asked questions
Why is 2100 not a leap year?
2100 divides by 100 but not by 400, so the century rule removes its leap day. The same happened in 1700, 1800 and 1900 — but 2000 kept its February 29.
Why do we need leap years at all?
Earth takes roughly 365 days and 6 hours to orbit the sun. Without the extra day those hours would pile up, drifting the calendar about 24 days per century until July fell in winter.
Is a leap year the same in every calendar?
No — this is the Gregorian rule. The Julian calendar leaps every 4 years without exception (why it drifted), and lunisolar calendars like the Hebrew one add whole leap months instead.
Related calculators
This calculator is for educational purposes. Double-check important results before acting on them.