A leap year checker determines if any year in history or the future is a leap year using the Gregorian calendar algorithm. It also explains which rule applies and shows nearby leap years on a visual timeline.
Nearby Leap Years
Leap Year Algorithm
Batch Mode
Enter multiple years separated by commas
How to Check Leap Years
A leap year has 366 days instead of 365. The extra day (February 29) is added to keep our Gregorian calendar synchronized with Earth's orbit around the Sun, which takes 365.2422 days.
The Three-Rule Algorithm
The Gregorian leap year rule has three conditions: First, the year must be divisible by 4. Second, if it is also divisible by 100, it is NOT a leap year. Third, if it is divisible by 400, it IS a leap year despite rule 2. This means: 2024 ÷ 4 = 506 (yes, leap); 1900 ÷ 100 = 19 but not ÷ 400 (not a leap); 2000 ÷ 400 = 5 (yes, leap).
Historical Examples
2024 is a leap year (divisible by 4, not by 100). 2000 was a leap year (divisible by 400). 1900 was NOT a leap year (divisible by 100 but not 400). 1600 WAS a leap year (divisible by 400). 2100 will NOT be a leap year (divisible by 100 but not 400).
Batch Checking
Enter multiple years separated by commas in the Batch Mode section to quickly check a range of years. This is useful for verifying date logic in software, researching historical calendars, or satisfying curiosity about specific years.
FAQ
Is the leap year checker free to use?
Yes, completely free with no signup required. Everything runs in your browser — no data is sent to any server. Check individual years or batch-check multiple years at once.
What is the leap year rule?
A year is a leap year if it is divisible by 4. However, years divisible by 100 are NOT leap years, UNLESS they are also divisible by 400. So 2000 was a leap year (÷400), but 1900 was not (÷100 but not ÷400). Next after 2024 is 2028.
Why do we have leap years?
The Earth takes approximately 365.25 days to orbit the Sun. Without leap years, our calendar would drift by about 6 hours every year — after 100 years, summer would start in September in the Northern Hemisphere. Leap years add an extra day every 4 years to keep the calendar aligned with the astronomical year.
When is the next leap year?
The next leap year after 2024 is 2028. Leap years occur every 4 years in most cases, with the exception of century years not divisible by 400 (2100, 2200, 2300 are NOT leap years, but 2400 will be).
What happens to people born on February 29?
People born on February 29 (leaplings) celebrate their birthday on February 28 or March 1 in non-leap years, depending on personal preference and local tradition. Legally, most jurisdictions treat March 1 as their birthday in non-leap years.
How do I check multiple years at once?
Use the Batch Mode section at the bottom of the tool. Enter years separated by commas (e.g., 2000, 1900, 2100, 2024) and click Check All to see a table of results for each year.