Leap Year Checker
Enter a year to see instantly whether it's a leap year, with the divide-by-4/100/400 rule explained, plus leap years in any range and the next or previous leap year from today.
Check a year
Leap years in a range
Next & previous leap year
Why leap years exist
A solar year — the time Earth actually takes to orbit the Sun — is about 365.2422 days, not a clean 365. Left uncorrected, a 365-day calendar would drift by roughly a day every four years, and after a few centuries the seasons would slide across the calendar entirely. Adding a 366th day (February 29) about once every four years brings the average calendar year to 365.25 days, much closer to the real figure. The Gregorian calendar, used almost everywhere today, then trims that "almost closer" with the 100/400 exception below, landing on an average of 365.2425 days per year — off from the true solar year by only about 26 seconds.
The three-step rule this tool checks
Every year is tested in the same order:
- Divisible by 4? If not, it's a common year (365 days) — stop here.
- Divisible by 100? If not, it's a leap year (366 days) — stop here.
- Divisible by 400? If yes, it's a leap year after all. If no, it's a common year.
In short: leap every 4 years, except century years, except when the century year is also divisible by 400. That double exception is what makes 1900 a common year but 2000 a leap year, even though both are divisible by 100.
Example 1 — an ordinary leap year. 2028 ÷ 4 = 507 exactly, and 2028 is not divisible by 100, so the check stops at step 1: 2028 is a leap year.
Example 2 — the century exception. 2100 ÷ 4 = 525 exactly, and 2100 ÷ 100 = 21 exactly, so step 2 triggers. 2100 ÷ 400 = 5.25, not a whole number, so step 3 fails too: 2100 is not a leap year, unlike the years right around it (2096 and 2104 both are).
Example 3 — the exception to the exception. 2000 ÷ 4 = 500, and 2000 ÷ 100 = 20, so step 2 also triggers. But 2000 ÷ 400 = 5 exactly, so step 3 passes: 2000 is a leap year after all.
Leap years around the year 2000
| Year | ÷4 | ÷100 | ÷400 | Leap year? |
|---|---|---|---|---|
| 1896 | Yes | No | — | Yes |
| 1900 | Yes | Yes | No | No |
| 2000 | Yes | Yes | Yes | Yes |
| 2024 | Yes | No | — | Yes |
| 2028 | Yes | No | — | Yes |
| 2100 | Yes | Yes | No | No |
Using the range and next/previous tools
The Leap years in a range section lists every leap year between two years you choose (up to a 500-year span, to keep the list readable) — handy for filling in a calendar, checking a birth-year cohort, or verifying a date library. The Next & previous leap year panel doesn't need any input: it reads your device's current date and reports the closest leap years before and after today, recalculated every time you open the page.
A note on dates before 1582
The rule above describes the Gregorian calendar, adopted in most of Europe starting in 1582 and eventually worldwide. Before that, the Julian calendar was in use, which added a leap day every 4 years with no century exception at all — so under the Julian rule, both 1900 and 2100 would have been leap years. This tool always applies the modern Gregorian rule, which is the standard convention for calendar software and for questions like "is 2028 a leap year," but historians working with pre-1582 dates should keep the distinction in mind.
Sources & further reading
Frequently asked questions
What makes a year a leap year? The three-part rule explained
A year is a leap year if it's divisible by 4 — except that years divisible by 100 are not leap years, unless they're also divisible by 400. So the check runs in three steps: divisible by 4? If not, it's not a leap year. If yes, is it divisible by 100? If not, it is a leap year. If yes, is it divisible by 400? If yes, it is a leap year after all; if not, it isn't. This extra correction exists because a calendar year of exactly 365.25 days would drift from the solar year, and the 100/400 exceptions trim that drift to about 26 seconds per year.
Is 2028 a leap year?
Yes. 2028 divided by 4 is 507 with no remainder, and 2028 is not divisible by 100, so the century exception doesn't apply — 2028 is a leap year with 366 days and a February 29. The same logic makes 2024 and 2032 leap years too, since they're each 4 years apart and none of them lands on a century year.
Why is 1900 not a leap year but 2000 is?
Both years are divisible by 100, which normally rules out a leap year — but 2000 is also divisible by 400 (2000 ÷ 400 = 5 exactly), so the century exception is itself excepted and 2000 is a leap year. 1900 divided by 400 leaves a remainder (1900 ÷ 400 = 4.75), so it stays a common year with 365 days. The same pattern applies to 1800, 1900, 2100, 2200, and 2300, which are all divisible by 4 and by 100 but not by 400, so none of them is a leap year.
How often do leap years occur, and when is the next one?
Leap years occur about once every 4 years, but not exactly — the century rule removes 3 leap years every 400 years, so the true average is 97 leap years per 400 years rather than 100. This checker's "Next & previous leap year" panel reads your device's clock and always shows the correct next and previous leap year relative to today, so you don't need to count by hand.
Fun facts about people born on February 29 (leaplings)
People born on February 29 are sometimes called "leaplings" or "leap day babies," and the odds of any given birthday landing on that date are roughly 1 in 1,461. In years without a February 29, leaplings typically celebrate on February 28 or March 1, and which one is treated as the "legal" birthday for things like driving age can actually vary by country. Famous leaplings include figures from entertainment and sports, and some leapling communities hold real February 29 parties only once every four years.