Leap Year Calculator — Check Any Year
Check if any year is a leap year, understand why, and find upcoming and past leap years. See also Date Calculator and Days Between Dates.
Leap Year Rules Explained
The Gregorian calendar uses three rules to determine leap years. These rules correct for the fact that a solar year is approximately 365.2422 days, not exactly 365 days.
Rule 1: A year is a leap year if it is divisible by 4.
Rule 2: EXCEPT if it is divisible by 100, then it is NOT a leap year.
Rule 3: UNLESS it is also divisible by 400, then it IS a leap year.
if (year % 400 == 0) → leap year
else if (year % 100 == 0) → NOT a leap year
else if (year % 4 == 0) → leap year
else → NOT a leap year
History of the Leap Year
The concept of a leap year was introduced by Julius Caesar in 46 BC with the Julian calendar, which added a leap day every 4 years. However, this overcorrected by about 11 minutes per year. By 1582, the calendar had drifted 10 days from the solar year. Pope Gregory XIII introduced the Gregorian calendar with the century rule (Rules 2 and 3 above), which reduced the average year length to 365.2425 days — very close to the actual solar year of 365.2422 days.
Leap Years 2000-2100 Reference Table
| Decade | Leap Years |
|---|---|
| 2000s | 2000, 2004, 2008 |
| 2010s | 2012, 2016 |
| 2020s | 2020, 2024, 2028 |
| 2030s | 2032, 2036 |
| 2040s | 2040, 2044, 2048 |
| 2050s | 2052, 2056 |
| 2060s | 2060, 2064, 2068 |
| 2070s | 2072, 2076 |
| 2080s | 2080, 2084, 2088 |
| 2090s | 2092, 2096 |
Note: 2100 is NOT a leap year (divisible by 100 but not 400).
Frequently Asked Questions
Why do we have leap years?
Earth takes approximately 365.2422 days to orbit the Sun. Without leap years, the calendar would drift about 1 day every 4 years, eventually causing seasons to shift relative to calendar months. Leap years keep the calendar aligned with Earth's orbital period.
Is 2100 a leap year?
No. While 2100 is divisible by 4, it is also divisible by 100 and NOT divisible by 400. The century rule (Rule 2) makes it a common year with 365 days.
Why was 2000 a leap year if century years usually are not?
2000 is divisible by 400, which triggers Rule 3 (the exception to the exception). Years divisible by 400 are always leap years. The next century leap year will be 2400.
How often do leap years occur?
Leap years occur every 4 years on average, but the century rule means there are exactly 97 leap years in every 400-year cycle (not 100). This gives an average of one leap year every 4.12 years.
What happens if you are born on February 29?
People born on Feb 29 (called "leaplings") typically celebrate their birthday on Feb 28 or March 1 in non-leap years. Legally, most jurisdictions consider March 1 as the birthday for age-related purposes in non-leap years.
When is the next leap year?
Enter the current year in the calculator and it will show you the next leap year. Leap years follow a predictable pattern: if the last leap year was 2024, the next ones are 2028, 2032, 2036, and so on (skipping century years not divisible by 400).
Does the leap year rule apply to all calendars?
No. The rules described here apply to the Gregorian calendar (used internationally). Other calendars like the Islamic, Hebrew, and Chinese calendars have different intercalation methods to keep aligned with astronomical cycles.