Leap Year Calculator

What Is a Leap Year?

A leap year is a year with 366 days instead of the usual 365. The extra day is added to February, which has 29 days instead of 28. Leap years occur approximately every 4 years to keep the calendar aligned with Earth's orbit around the Sun, which takes about 365.2422 days. Without this correction, the calendar would drift by roughly 24 days every 100 years, causing seasons to shift out of alignment.

Leap Year Rules

1. If a year is divisible by 4, it is a leap year.
2. Except if it is also divisible by 100 — then it is not a leap year.
3. Unless it is also divisible by 400 — then it is a leap year.

Examples: 2024 (÷4 = leap year), 1900 (÷100 = not leap), 2000 (÷400 = leap year).

List of Leap Years

See the complete list of leap years (1800–2400) →

How Many Days in a Leap Year?

A leap year has 366 days (365 + 1). The extra day is February 29. In a regular year, February has 28 days; in a leap year, it has 29.

How Often Is a Leap Year?

Leap years occur every 4 years, except for century years not divisible by 400. This means there are exactly 97 leap years every 400 years (not 100). The next 5 leap years are: 2028, 2032, 2036, 2040, 2044.

Leap Day — February 29

February 29 is called Leap Day. People born on this date — known as "leaplings" — technically only have a birthday every 4 years. In non-leap years, they usually celebrate on February 28 or March 1. There are approximately 5 million people worldwide born on February 29.