Leap Year Checker
Check whether any year is a leap year, see why, and find the next leap years.
2024 is divisible by 4 and not by 100, so it is a leap year.
- 2028
- 2032
- 2036
- 2040
- 2044
A year is a leap year if it divides evenly by 4, except century years, which must also divide by 400. So 2024 is a leap year (divisible by 4, not by 100) and gets a 29-day February, while 1900 was not (divisible by 100 but not 400) and had 28 days.
What makes a year a leap year
A common year has 365 days; a leap year adds one extra day — 29 February — to make 366. Leap years keep the calendar aligned with Earth’s orbit, which takes about 365.2422 days rather than a tidy 365. Under the Gregorian calendar the rule has three parts: a year divisible by 4 is a leap year, unless it is also divisible by 100, in which case it is not — unless it is further divisible by 400, in which case it is. That is why 2000 was a leap year but 1900 and 2100 are not.
Gregorian leap-year rule
- 1 Divide the year by 4. If it does not divide evenly, it is a common year and you can stop. 2024 ÷ 4 leaves no remainder, so it stays in the running.
- 2 Check divisibility by 100. If the year is not divisible by 100, it is a leap year. 2024 is not divisible by 100, so 2024 is confirmed a leap year.
- 3 For century years, divide by 400. If the year is divisible by 100, it is only a leap year when it is also divisible by 400. 1900 ÷ 400 leaves a remainder, so 1900 is not a leap year; 2000 ÷ 400 is exact, so 2000 is.
- 4 Read February’s length. A leap year gives February 29 days; a common year gives it 28. That extra day is the whole point of the rule.
Leap year examples
How the three-part rule decides a few well-known years.
| Year | Leap year? | February | Why |
|---|---|---|---|
| 2000 | Yes | 29 days | Divisible by 400 (century leap year) |
| 1900 | No | 28 days | Divisible by 100 but not 400 |
| 2024 | Yes | 29 days | Divisible by 4, not by 100 |
| 2100 | No | 28 days | Divisible by 100 but not 400 |
| 2023 | No | 28 days | Not divisible by 4 |
Why the 400-year exception exists
Adding a leap day every 4 years assumes the year is exactly 365.25 days long, but the tropical year is closer to 365.2422 days — about 11 minutes shorter. Left alone, that tiny gap would push the seasons off the calendar by roughly three days every 400 years. The Gregorian fix drops three leap days per 400 years by skipping the century leap years that are not divisible by 400 (1700, 1800, 1900, 2100 …), which trims the average year to about 365.2425 days — very close to the true figure and accurate to a day over thousands of years.