Leap Year Checker
Instantly verify any year and learn the mathematical rules behind the leap day.
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The Leap Rule
The year must be evenly divisible by 4.
If it is divisible by 100, it is NOT a leap year...
...UNLESS the year is also divisible by 400.
Why do we have Leap Years?
A common misconception is that the Earth orbits the sun in exactly 365 days. In reality, it takes approximately 365.2422 days.
Without that extra day on February 29th every four years, our calendar would drift out of sync with the solar year by about 6 hours annually. After 100 years, our seasons would be off by 24 days! The Gregorian calendar rules ensure we stay perfectly aligned with the Earth's orbit.
Days in a Leap Year
The Leap Day
Leap Years per 400y