Leap Year Calculator
Leap Year Rules
Rule 1: Divisible by 4
If a year is divisible by 4, it might be a leap year.
Rule 2: Century Exception
However, if divisible by 100, it is NOT a leap year...
Rule 3: 400-Year Exception
...unless it's also divisible by 400, then it IS a leap year.
Examples
2000 ✓ (÷400), 1900 ✗ (÷100 but not ÷400), 2024 ✓ (÷4), 2023 ✗ (not ÷4)
Recent Leap Years
Related Calculators
Understanding Leap Years
Why Do Leap Years Exist?
Earth takes approximately 365.2422 days to orbit the sun. If we used exactly 365 days per year, our calendar would drift about 6 hours per year. After 100 years, the calendar would be off by about 24 days!
The Math
- Actual year: 365.2422 days
- Calendar year: 365 days
- Difference: 0.2422 days ≈ 5 hours 49 minutes
- Over 4 years: ~1 full day
The Complete Rules
Rule 1: Divisible by 4
A year is a leap year if it's divisible by 4.
Examples: 2024, 2028, 2032
Rule 2: Century Exception
EXCEPT years divisible by 100 are NOT leap years.
Examples: 1700, 1800, 1900 (not leap years)
Rule 3: 400-Year Exception
EXCEPT years divisible by 400 ARE leap years.
Examples: 1600, 2000, 2400 (are leap years)
Why the Complex Rules?
| System | Avg Year Length | Error per Year |
|---|---|---|
| No leap years | 365.0000 days | 5h 49m |
| Leap every 4 years | 365.2500 days | 11 min |
| + Skip centuries | 365.2400 days | -3 min |
| + Keep every 400 | 365.2425 days | 27 sec |
Leap Year Statistics
Born on February 29
People born on February 29 (called "leaplings") only have their actual birthday every 4 years. In non-leap years, they typically celebrate on February 28 or March 1.
Fun Facts
- About 4 million people worldwide were born on February 29
- The odds of being born on Feb 29 are about 1 in 1,461
- 2000 was a leap year (divisible by 400), but 1900 was not
- The Gregorian calendar will be off by 1 day in about 3,236 years
Frequently Asked Questions
How do I know if a year is a leap year?
A year is a leap year if: (1) it's divisible by 4, AND (2) if divisible by 100, it must also be divisible by 400. So 2024 is a leap year (divisible by 4), 1900 was not (divisible by 100 but not 400), and 2000 was (divisible by 400).
Why do we have leap years?
Earth takes approximately 365.2422 days to orbit the sun, not exactly 365. Without leap years, our calendar would drift about 24 days every 100 years. Adding February 29 every 4 years (with century exceptions) keeps our calendar aligned with Earth's orbit.
When is the next leap year?
Leap years occur every 4 years on years divisible by 4. Recent and upcoming leap years: 2020, 2024, 2028, 2032, 2036, 2040. The exception is century years not divisible by 400 (like 2100).
What happens if you're born on February 29?
People born on February 29 ('leaplings') typically celebrate their birthday on February 28 or March 1 in non-leap years. Legally, their birthday documentation shows Feb 29, but they can choose when to celebrate during common years.