Leap Year Calculator - Check if Year is Leap Year Online
Free online leap year calculator to check if a year is a leap year. Learn leap year rules and calculate leap years for any year.
Year Information
Leap Year Results
Enter a year to check if it's a leap year
About Leap Year Calculator
The Leap Year Calculator helps you determine if a year is a leap year using the Gregorian calendar rules.
Leap Year Rules:
- Rule 1: Year must be divisible by 4
- Rule 2: If divisible by 100, must also be divisible by 400
- Exception: Years divisible by 100 but not 400 are not leap years
Examples:
- 2024: Divisible by 4 ✓ (Leap year)
- 2000: Divisible by 4, 100, and 400 ✓ (Leap year)
- 1900: Divisible by 4 and 100, but not 400 ✗ (Not leap year)
- 2023: Not divisible by 4 ✗ (Not leap year)
Why Leap Years Exist:
- Earth's orbit around the sun takes ~365.25 days
- Calendar year has 365 days
- Extra 0.25 days accumulate over 4 years
- Leap year adds February 29th to compensate
Applications:
- Calendar and date calculations
- Age calculations
- Project planning
- Financial calculations
- Educational purposes
Historical Context:
- Introduced by Julius Caesar in 45 BCE
- Refined by Pope Gregory XIII in 1582
- Gregorian calendar is used worldwide today
- Some cultures use different calendar systems
Note: This calculator uses the Gregorian calendar rules. Other calendar systems may have different leap year rules.
Frequently Asked Questions
What is a leap year?
A leap year is a year that has 366 days instead of 365. An extra day (February 29th) is added to keep the calendar year synchronized with the astronomical year.
How do I know if a year is a leap year?
A year is a leap year if it's divisible by 4, except for years divisible by 100 unless they're also divisible by 400.
Why do we have leap years?
Leap years exist because Earth's orbit around the sun takes approximately 365.25 days, but our calendar year has 365 days. The extra 0.25 days accumulate over 4 years, requiring an extra day.
What happens to people born on February 29th?
People born on February 29th celebrate their birthday on February 28th or March 1st in non-leap years, depending on local customs.
Are there other calendar systems with different leap year rules?
Yes, different calendar systems have different leap year rules. For example, the Islamic calendar uses a different system based on lunar cycles.