Leap Year Calculator
Select any year to check if it is a leap year and review its astronomical status.
The Mechanics of Leap Years
What makes a year a leap year?
A year is a leap year if it is divisible by 4. However, century years (ending in 00) must also be divisible by 400 to qualify (e.g., 2000 was a leap year, but 1900 was not).
Why do we need leap years?
Earth takes approximately 365.2422 days to complete one full orbit around the Sun. Leap years realign our calendar with Earth's tropical solar year.