Leap Year Calculator
Enter a year to check if it’s a leap year (366 days). Explains the 4/100/400 rule and shows why a year is or isn’t a leap year.
Leap Year Calculator tool
Enter an integer year (e.g., 2024). This tool uses the Gregorian leap-year rule.
Privacy: runs locally in your browser. No inputs or results are stored or transmitted.
Leap year rule (Gregorian):
- Divisible by 4 → leap year
- But divisible by 100 → not a leap year
- Unless divisible by 400 → leap year again
Examples
- 2024 → leap year (divisible by 4, not by 100)
- 1900 → not a leap year (divisible by 100, not by 400)
- 2000 → leap year (divisible by 400)
FAQ
- What is a leap year?
A leap year is a year with 366 days (February has 29 days) in the Gregorian calendar.
- What is the leap year rule?
A year is a leap year if it is divisible by 4, except years divisible by 100 are not leap years unless they are also divisible by 400.
- Is 1900 a leap year? What about 2000?
1900 is not a leap year (divisible by 100 but not by 400). 2000 is a leap year (divisible by 400).
- Does this apply to all countries and all history?
This calculator uses the modern Gregorian leap-year rule. Historical calendar usage varies by region and period.
- Do you store my input?
No. This runs locally in your browser. Inputs are not stored or transmitted.