Understanding the result
The result states whether the year is a leap year and quotes the rule that applies to it. A leap year has 366 days because February has a 29th day; other years have 365.
The previous and next leap years help you see where the year sits in the four-year cycle and where century exceptions fall.
What is a leap year?
A leap year is a year with an extra day, 29 February, added to keep the calendar aligned with the Earth's orbit around the Sun. A solar year is about 365.2422 days, so without an occasional extra day the calendar would drift against the seasons.
How it works
The Gregorian calendar uses three rules: a year is a leap year if it is divisible by 4; except that century years (divisible by 100) are not leap years; except that century years divisible by 400 are leap years.
So 2024 is a leap year (divisible by 4). 1900 and 2100 are not (century years not divisible by 400). 2000 and 2400 are (divisible by 400).
Across 400 years this gives 97 leap years, an average year length of 365.2425 days.
Examples
2000
Divisible by 400, so it is a leap year, even though it is a century year.
1900 and 2100
Both are divisible by 100 but not by 400, so neither is a leap year. That is why the gap between leap years around them is eight years, not four.
2024
Divisible by 4 and not a century year, so it is a leap year. The previous leap year is 2020 and the next is 2028.
Things to keep in mind
- The Gregorian rule is applied to all years, including those before its introduction in 1582. Under the older Julian calendar every fourth year was a leap year with no century exception.
- People born on 29 February may celebrate on 28 February or 1 March in other years, depending on custom and law.
- The tool supports years from 1 to 9999.