Leap Year Checker
Check whether a given year is a leap year according to the Gregorian calendar rules.How to Use
- 1Enter any year (e.g. 2024) in the year input field.
- 2Click 'Check' to instantly see whether the year is a leap year or not.
- 3The result shows a clear leap year / not a leap year indicator with the day count (366 or 365).
- 4You can enter any year from 1 to 9999 to check the Gregorian calendar leap year status.
- 5Click 'Clear' to reset the form and check another year.
About Leap Years
Gregorian Leap Year Rules
A year is a leap year in the Gregorian calendar if: (1) it is divisible by 4 AND (2) if divisible by 100, it must also be divisible by 400. So 2000 was a leap year, but 1900 was not. This adjustment keeps the calendar aligned with Earth's solar orbit of approximately 365.2425 days.
Why Leap Years Exist
Earth takes about 365.25 days to orbit the Sun. Without leap years, the calendar would drift by about 6 hours per year — after 100 years, seasons would be off by 25 days. Julius Caesar introduced the Julian calendar with a leap year every 4 years; Pope Gregory XIII refined it in 1582 with the century rules to further reduce the drift.
Leap Year in Different Calendars
The Julian calendar adds a leap year every 4 years without exception. The Hebrew calendar uses a 19-year cycle with 7 leap years (adding an extra month, not a day). The Islamic calendar is purely lunar and does not have leap years in the solar sense. The Chinese calendar is lunisolar with its own intercalation rules.