Leap Year Calculator
Check whether a year is a leap year under the Gregorian rule, see why, and find the next ones.
Answer
2026 is not a leap year
- Why
- 2026 is not divisible by 4.
- Length of the year
- 365 days
- February
- 28 days
- Next leap years
- 2028, 2032, 2036, 2040, 2044, 2048
Whether a year has a 29 February, which clause of the rule decided it, and the leap years that follow.
How it works
The Gregorian rule has three clauses, applied in order: a year divisible by 4 is a leap year, except that a year divisible by 100 is not, except that a year divisible by 400 is after all. So 1900 was an ordinary year and 2000 was a leap year.
The reason for the exceptions is that the tropical year is about 365.2422 days, not 365.25. Adding a day every four years overcorrects by roughly three days in four hundred years, and dropping three century leap days puts it back.
Dates before the Gregorian calendar was adopted are shown under the same rule, applied backwards. That is the proleptic Gregorian calendar, and it is what ISO-8601 and most software use; it is not what the calendar in use at the time would have said.
Examples
| Case | Input | Result |
|---|---|---|
| A century that is not a leap year | 1900 | Not a leap year: divisible by 4, but a century not divisible by 400 |
Frequently asked questions
Is every fourth year a leap year?
Almost. Three times in every four hundred years the century exception removes one: 1700, 1800 and 1900 were not leap years, and 2100, 2200 and 2300 will not be. 2000 was, because it is divisible by 400.
Why does the calendar need leap years at all?
A year is not a whole number of days. Without a correction the calendar drifts against the seasons by about a day every four years, which is a month per century.
Are the results reliable for very old years?
They apply the Gregorian rule to every year, including those before it existed. That is the standard convention in software and it is internally consistent, but it does not describe what any historical calendar actually did. Countries adopted the Gregorian calendar at different dates, from 1582 to the twentieth century.
Good to know
- The proleptic Gregorian calendar is used throughout, which means the modern rule is applied to years before its adoption.