How do I determine if a year is a leap year?

A year is a leap year if: (1) it is divisible by 4, AND (2) if it is a century year (divisible by 100), it must also be divisible by 400. Examples: 2000 (leap - divisible by 400), 1900 (not a leap year - divisible by 100 but not 400), 2024 (leap - divisible by 4 but not 100).

Why do we have leap years?

Earth takes approximately 365.2422 days to orbit the sun. Without leap years, our calendar would drift about 6 hours per year - losing an entire day every 4 years. Over centuries, seasons would shift significantly. Julius Caesar introduced leap years in 46 BC; Pope Gregory XIII refined the rule in 1582.

Was 2000 a leap year?

Yes, 2000 was a leap year. It is divisible by both 100 and 400, so it qualifies as a leap year under the Gregorian calendar. The previous century leap year was 1600, and the next will be 2400.

When is the next leap year?

The next leap years are 2028, 2032, 2036, and 2040. The last leap year was 2024. 2100 will NOT be a leap year (divisible by 100 but not 400).

Leap Year Calculator - Is This Year a Leap Year?

Leap Year Calculator

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About the Leap Year Calculator

Enter any year to instantly find out if it is a leap year. The calculator uses the Gregorian calendar rules and also shows you the nearest leap years and key facts about the year.

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Leap Year Rule Summary

A year is a leap year if it is divisible by 4, except for end-of-century years, which must be divisible by 400. So 2000 and 2400 are leap years, but 1700, 1800, and 1900 are not.

The Gregorian Leap Year Rules

The Gregorian calendar introduced in 1582 refined the Julian calendar's simple every-4-years rule. The Gregorian rules are: (1) A year divisible by 4 is a leap year; EXCEPT (2) years divisible by 100 are NOT leap years; UNLESS (3) they are also divisible by 400, in which case they ARE leap years. This gives an average year length of 365.2425 days — matching the tropical year (time for Earth to orbit the Sun) to within 26 seconds. The Julian calendar's 365.25-day average accumulated an error of about 3 days every 400 years, which over 1,000 years shifted the calendar by about 8 days.

The 400-year Gregorian cycle contains exactly 97 leap years: years divisible by 4 = 100, minus century years = 4, plus 400-year years = 1, giving 100 − 4 + 1 = 97. The next leap year century will be 2400. Countries adopted the Gregorian calendar at different times: Britain and its colonies in 1752, Russia in 1918, Greece in 1923.

Year	Divisible by 4?	Divisible by 100?	Divisible by 400?	Leap Year?
1900	Yes	Yes	No	No
2000	Yes	Yes	Yes	Yes
2024	Yes	No	—	Yes
2100	Yes	Yes	No	No
2400	Yes	Yes	Yes	Yes
2023	No	—	—	No

Year

Divisible by 4?

Divisible by 100?

Divisible by 400?

Leap Year?

1900

Yes

2000

Yes

2024

Yes

—

Yes

2100

Yes

2400

Yes

2023

—

Leap Year Calculator

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Leap Year Rule Summary

The Gregorian Leap Year Rules

Leap Year Examples

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