Leap Year Calculator
Enter a year to check whether it's a leap year and see how many days it has.
How the leap year rule works
A year is a leap year if it's divisible by 4, except for century years (divisible by 100), which must also be divisible by 400 to qualify. This keeps the calendar year aligned with Earth's orbit around the sun, which takes about 365.2425 days.
For example, 2000 was a leap year (divisible by 400), but 1900 was not (divisible by 100 but not 400). Most leap years, like 2024 and 2028, are simply divisible by 4.
Frequently asked questions
What is a leap year?
A leap year is a year with an extra day — February 29th — added to keep the calendar synchronized with Earth's orbit around the sun. Leap years have 366 days instead of 365.
How do I know if a year is a leap year?
A year is a leap year if it's divisible by 4. The exception is century years: they must be divisible by 400, not just 100, to be a leap year.
Why was the year 1900 not a leap year but 2000 was?
Both are divisible by 100, but 1900 isn't divisible by 400 while 2000 is. This century-year exception keeps the calendar accurate over long periods.