About the Leap Year Checker
This leap year checker tells you instantly whether a year is a leap year under the Gregorian calendar, explains which rule decides it, and shows the number of days in the year and in February. It also finds the previous and next leap years and lists upcoming leap years with the day of the week each February 29 falls on.
It is useful for programmers testing date logic, payroll and finance teams working out daily interest or 366-day years, parents of “leaplings” born on February 29, and students learning why 1900 was not a leap year but 2000 was.
The Gregorian rule has three parts: a year divisible by 4 is a leap year, except years divisible by 100, which are not — unless they are also divisible by 400. The checker applies that rule to any year from 1 to 9995 (the proleptic Gregorian calendar); for years before a country adopted the Gregorian calendar (1582 in Catholic Europe, 1752 in Britain and its colonies) historical calendars may differ.
How to use the leap year checker
- 1Enter the year you want to check.
- 2Read whether it is a leap year and which rule decides it.
- 3See the previous and next leap years and the next February 29.
- 4Adjust how many upcoming leap years to list in the table.
Formula and method
A solar (tropical) year lasts about 365.2422 days. Adding a leap day every 4 years gives an average of 365.25 days — slightly too long — so the Gregorian calendar skips the leap day in century years unless they are divisible by 400. That removes 3 leap days every 400 years, for an average year of 365.2425 days, within about 26 seconds of the solar year.
The checker applies the rule to the chosen year, then steps forwards and backwards one year at a time to find the nearest leap years. The weekday of each February 29 comes from the proleptic Gregorian calendar.
- year mod n
- Remainder after dividing the year by n
Worked examples
Is 2028 a leap year?
2028 ÷ 4 = 507 with no remainder, and it is not a century year, so it is a leap year with 366 days. February 29, 2028 is a Tuesday; the next leap year after it is 2032.
Why 1900 was not a leap year
1900 is divisible by 4 and by 100 but not by 400, so the century exception applies and it has 365 days. The leap years around it were 1896 and 1904 — an 8-year gap.
The year 2000
2000 is divisible by 400, which overrides the century exception, so it was a leap year. February 29, 2000 fell on a Tuesday.
Is 2026 a leap year?
2026 ÷ 4 leaves a remainder of 2, so it is a common year with a 28-day February. The next leap day is February 29, 2028.
Frequently asked questions
How do you know if a year is a leap year?+
A year is a leap year if it is divisible by 4, except century years (divisible by 100), which must also be divisible by 400. So 2024 and 2028 are leap years, 1900 and 2100 are not, and 2000 was.
When is the next leap year?+
The next leap year after 2026 is 2028, followed by 2032, 2036 and 2040. Leap years occur every four years except for century years not divisible by 400; the next skipped one is 2100.
Why do we have leap years?+
Earth takes about 365.2422 days to orbit the Sun. Without an extra day roughly every four years, the calendar would drift about 24 days per century and the seasons would slowly shift away from their usual months.
How are birthdays handled for people born on February 29?+
Leap-day babies celebrate on February 29 in leap years. In common years most choose February 28 or March 1; many legal systems treat March 1 as the anniversary for reaching an age, but rules vary by country.
How many leap years are there in 400 years?+
There are 97 leap years in every 400-year Gregorian cycle: 100 years divisible by 4, minus 3 century years not divisible by 400. That gives an average year of 365.2425 days.