Datetime Tools
Leap year checker.
Enter any year and we'll tell you whether it's a leap year under the real Gregorian calendar rule, plus the nearest leap years before and after it.
Inputs
Result
Enter a year and press Check year.
The leap year rule
A year is a leap year in the Gregorian calendar if it satisfies one of these conditions, checked in order:
- It is divisible by 400 — always a leap year (e.g. 2000).
- It is divisible by 100 but not by 400 — not a leap year (e.g. 1900, 2100).
- It is divisible by 4 but not by 100 — a leap year (e.g. 2024, 2028).
- Otherwise, it is not a leap year (e.g. 2026, 2027).
The extra day, February 29, exists because Earth's orbit takes about 365.2422 days, not an even 365. Adding a day every 4 years overcorrects slightly, so centuries not divisible by 400 skip the leap day to keep the calendar aligned with the seasons over the long run.