Leap Year Calculator
Check whether a year is a Gregorian leap year. Divisible by 4, except centuries that are not divisible by 400. The page also reports February length and year length.
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How to check a leap year
- Enter a year from 1 to 9999. The default 2024 is a leap year.
- Read Yes or No, February days, and 365 or 366.
- Centuries must be divisible by 400. 1900 is not a leap year. 2000 is.
- This is the Gregorian rule only. Nothing is uploaded.
Gregorian leap year
Divisible by 4, with the 400-year century exception
| Common year | 365 days, February has 28 |
|---|---|
| Leap year | 366 days, February has 29 |
| Rule of 4 | Most years divisible by 4 are leap years |
| Century exception | A century year is a leap year only if it is divisible by 400 |
| Default | 2024 is a leap year |
| Calendar | Gregorian. Not Julian. |
What a Gregorian leap year is
Most years divisible by 4 add 29 February. Century years (1800, 1900, 2100) do not, unless they are also divisible by 400. 2000 is a leap year. 1900 is not. 2024 is.
February, century, and the 400-year cycle
February is the month that grows. A century year ends in 00. The 400-year exception keeps the mean year close to the tropical year. A full month table for a year lives on the year calendar.
How this page tests the year
The page applies the Gregorian rule in this browser and reports February length from the local civil calendar. Year must be from 1 to 9999.
Limits
Julian leap years (every 4 years with no 400 rule) are not used. Proleptic Gregorian applies before 1582 on this page. CZNull does not receive the year. See the disclaimer.