Leap Year Checker
Check whether a year is a leap year, see why, and list every leap year in a range.
—
- —Divisible by 4
- —Divisible by 100
- —Divisible by 400
—
- Days in the year
- —
- Days in February
- —
- Leap day falls on
- —
- Previous leap year
- —
- Next leap year
- —
- Next five leap years
- —
List every leap year in a range
—
—
How it works
This checker uses the Gregorian calendar rule, the one almost every country uses today: a year is a leap year if it is divisible by 4, except years divisible by 100, unless they are also divisible by 400. That is why 1996 and 2024 are leap years, 1900 and 2100 are not, and 2000 was. The exception exists because the Earth takes about 365.2422 days to orbit the Sun — adding a day every four years overshoots slightly, so three leap days are skipped every 400 years, leaving an average year of 365.2425 days.
A leap year has 366 days and February gains a 29th day. For leap years the tool also shows which weekday 29 February lands on, the previous and next leap years, and the next five after the year you entered. The range lister prints every leap year between two years, inclusive. Years before 1582 are treated with the proleptic Gregorian rule (the modern rule projected backwards), which differs from the historical Julian calendar, where every fourth year was a leap year with no century exception. Everything is computed in your browser with plain JavaScript — nothing is uploaded, there is no signup and there are no ads.
Frequently asked questions
What makes a year a leap year?
A year is a leap year if it is divisible by 4, except years divisible by 100, unless they are also divisible by 400. So 2024 and 2000 are leap years while 1900 and 2100 are not.
Why is 2100 not a leap year?
The solar year is about 365.2422 days, slightly under 365.25. Skipping the leap day in three of every four century years removes the accumulated overshoot and keeps the calendar aligned with the seasons.
When is the next leap year?
Enter a range and the checker lists every leap year inside it, so the next one after any date you care about is one lookup away.