Leap Year Calculator
Check if any year is a leap year, list all leap years in a range, calculate leap year probability, and explore calendar rules.
Leap Year?
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Days in Year —
Next Leap Year —
Previous Leap Year —
Extended More scenarios, charts & detailed breakdown ▾
Leap Year?
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Days in Year —
Next Leap Year —
Previous Leap Year —
Professional Full parameters & maximum detail ▾
Calendar Rules
Gregorian Leap Year? —
Julian Leap Year? —
Century Year Note —
Statistics
Days Until Next Feb 29 —
Total Leap Years Since Year 1 —
How to Use This Calculator
- Enter any year to instantly check if it is a leap year.
- See days in the year (365 or 366), previous and next leap years.
- Use List Leap Years to see all leap years in a custom range.
- Use Fun Facts for leap day baby statistics and probability.
- The Professional tier covers Gregorian vs Julian rules, century exceptions, and days until next Feb 29.
Formula
Leap Year Rule: (year % 4 === 0) AND (year % 100 !== 0 OR year % 400 === 0)
Examples: 2024 → yes | 1900 → no (÷100 but not ÷400) | 2000 → yes (÷400)
Example
Example: Year 2024 — divisible by 4 ✓, not a century year ✓ → Leap Year (366 days). Year 1900 — divisible by 4 ✓, divisible by 100 ✓, NOT divisible by 400 → Not a leap year (365 days).
Frequently Asked Questions
- A Gregorian leap year must satisfy: (1) divisible by 4; AND (2) if divisible by 100, must also be divisible by 400. So 2000 is a leap year, but 1900 is not.
- After 2024, the next leap years are 2028, 2032, 2036, and 2040. They occur every 4 years, except century years not divisible by 400.
- A leap second is occasionally added to UTC to account for the slight slowing of Earth's rotation. Unlike leap years, these are unpredictable and decided by the IERS. The last leap second was added on December 31, 2016.
- Approximately 1 in 1,461 (about 0.068%), since leap day occurs once every 4 years. There are roughly 5 million "leaplings" worldwide.
- The Hebrew calendar adds a 13th month 7 times in a 19-year cycle. The Islamic calendar is purely lunar (no leap years for alignment). The Chinese calendar adds a leap month roughly every 3 years.