Leap Year Calculator

Check whether any year from 1000 to 9999 is a leap year, and see the previous and next ones. The leap year calculator can also list every leap year in a range.

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List leap years in a range (optional)

Leap year?
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How to use the Leap Year Calculator

  1. Enter a Year.
  2. To list leap years, fill in From year and To year.
  3. Press Calculate. You get a yes or no with the reason, the leap years either side, and the list.

How it works

A Gregorian year is a leap year when:

  • it is divisible by 4, and
  • it is not divisible by 100, unless it is also divisible by 400.
leap = (year % 4 = 0 and year % 100 ≠ 0) or year % 400 = 0

Examples

  • 2024: divisible by 4 and not a century year, so a leap year with 366 days.
  • 1900: a century year not divisible by 400, so not a leap year.
  • 2000: divisible by 400, so a leap year.

Why leap years exist

Earth takes about 365.2422 days to go around the Sun. Adding a day every 4 years overshoots slightly, so the Gregorian calendar skips three leap days every 400 years. That keeps the average year at 365.2425 days, close enough to stay within a day of the seasons for over 3,000 years.

Limitations

  • Years from 1000 to 9999 are supported, using the Gregorian rule even before it was adopted in 1582.
  • Ranges are limited to 2,000 years.

Frequently asked questions

Is 2024 a leap year?

Yes. 2024 is divisible by 4 and is not a century year.

Why was 1900 not a leap year?

Century years are leap years only when divisible by 400. 1900 is not, so it had 365 days.

When is the next leap year?

Enter the current year and the calculator shows the next one. After 2024, it is 2028.

Often used together with the Leap Year Calculator.