Leap Year Checker
Check whether a year is a leap year and list nearby leap years.
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How it works
Enter a year and the tool applies the Gregorian leap-year rules: a year is a leap year if it is divisible by 4, except century years, which must be divisible by 400. So 2000 is a leap year but 1900 is not. Leap years have 366 days with a February 29. The tool also lists the next several leap years. All checking runs locally in your browser with simple arithmetic.
leap if (year % 4 = 0 and year % 100 ≠ 0) or year % 400 = 0
Common use cases
- Checking whether a given year has a February 29.
- Finding the next leap year for planning.
- Verifying a date calculation that spans a leap year.
Frequently asked questions
Why is 1900 not a leap year but 2000 is?
Century years are leap years only if divisible by 400. 1900 is divisible by 100 but not 400, so it is not a leap year; 2000 is divisible by 400, so it is.
Why do leap years exist?
A solar year is about 365.24 days. Adding a day every four years keeps the calendar aligned with the seasons; the century rules fine-tune the small remaining error.
How many days are in a leap year?
366 — an extra day, February 29, is added to the usual 365.