Leap Year Calculator
About Leap Year Calculator
What Is a Leap Year?
A leap year is a year with 366 days instead of the usual 365. The extra day is added as February 29. Leap years exist because Earth's orbit around the sun takes approximately 365.2422 days, not exactly 365. Without leap years, the calendar would drift by about one day every four years, eventually causing seasons to shift relative to calendar months. The leap year system keeps the calendar aligned with Earth's position in its orbit.
Leap Year Rules
In the Gregorian calendar, a year is a leap year if: (1) it is divisible by 4, AND (2) if divisible by 100, it must also be divisible by 400. So 2024 is a leap year (divisible by 4), 1900 was NOT (divisible by 100 but not 400), and 2000 WAS (divisible by 400). This system gives an average year length of 365.2425 days, very close to the actual 365.2422.
How to Use This Calculator
Enter a year and click Check. The calculator tells you whether it is a leap year, shows the next and previous leap years, and displays a list of all leap years in the surrounding decade. It also shows which rule determined the result.
Frequently Asked Questions
Why was 1900 not a leap year?
1900 is divisible by 4 and by 100, but not by 400. The century rule (divisible by 100 must also be divisible by 400) prevents 1900 from being a leap year. This corrects for the slight overcorrection of the every-4-years rule.
How often do leap years occur?
Usually every 4 years. In any 400-year cycle, there are exactly 97 leap years (not 100, because 3 century years are skipped).
What happens if you are born on February 29?
People born on February 29 (leaplings) typically celebrate on February 28 or March 1 in non-leap years. Legally, the exact practice varies by jurisdiction.
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