Leap Year Calculator

Instantly determine if a year is a leap year. Use this tool to check past dates or plan for the future.

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Gregorian Rules

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Past & Future

The Rules of Leap Years

It's a common misconception that every year divisible by 4 is a leap year. While mostly true, there are exceptions. The rules are:

A year is a leap year if it is evenly divisible by 4.
However, if the year is also divisible by 100, it is NOT a leap year.
Unless... the year is also divisible by 400, in which case it IS a leap year.

For example, the year 2000 was a leap year (divisible by 400), but 1900 was not (divisible by 100 but not 400).

Why Do We Have Leap Years?

We have leap years to keep our calendar in alignment with the Earth's revolutions around the Sun.

Solar Year It takes Earth about 365.2422 days to orbit the Sun.

Correction Without leap days, we would lose about 6 hours every year.

A leap year has 366 days, instead of the usual 365. The extra day is added to February as February 29th.

Yes, occasionally "leap seconds" are added to Coordinated Universal Time (UTC) to compensate for the slowing of Earth's rotation.