Leap year checker
Type a year to find out whether it is a leap year with 366 days. The tool shows which part of the rule applies and lists the five leap years before and after.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Type a year between 1 and 9999.
- The result says whether it is a leap year, how many days it has and which clause of the rule applies.
- The lists show the next five and the previous five leap years.
The rule
- If the year is divisible by 400, it is a leap year (2000, 2400).
- Otherwise, if it is divisible by 100, it is not (1900, 2100, 2200).
- Otherwise, if it is divisible by 4, it is a leap year (2024, 2028).
- All other years are common years with 365 days.
Worked example
The years after 2026: 2028, 2032, 2036, 2040, 2044. The years after 2096: 2104 and 2108, because 2100 is divisible by 100 but not by 400 and is skipped. Leap years usually come every 4 years, and the gap is 8 years across a skipped century year.
What leap years change
A leap year adds 29 February, so the year has 366 days and every date after February falls one day later in the year. People born on 29 February celebrate on 28 February or 1 March in other years, depending on local custom.
Frequently asked questions
How do you know if a year is a leap year?
In the Gregorian calendar a year is a leap year if it is divisible by 4, except for century years, which must be divisible by 400. That makes 2024 and 2000 leap years, and 1900 and 2100 common years.
Why do we have leap years?
The Earth needs about 365.2422 days to go round the Sun. Adding one day every fourth year would be slightly too much, so three leap days are skipped every 400 years, which brings the calendar year to an average of 365.2425 days.
Was 1900 a leap year?
Not in the Gregorian calendar, because 1900 is divisible by 100 but not by 400. Some software wrongly treats 1900 as a leap year for compatibility reasons, which is a known quirk of spreadsheets.
Does the rule work for years before 1582?
The tool applies the Gregorian rule to every year, as a proleptic calendar. Before the switch from the Julian calendar (1582 or later, depending on the country), every year divisible by 4 was a leap year, including 1500 and 1700.