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.
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.
How it works
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)
When to use this tool
This tool is designed for quick, practical tasks such as everyday calculations, data formatting, or simple conversions. It is best used when you need fast results without installing software or using complex tools.
When to use
- Quick checks or one-time calculations
- Validating or converting data before using it elsewhere
- Simple tasks that do not require advanced software
When not to use
- Critical financial, legal, or medical decisions
- Large-scale or automated processing
- Situations requiring guaranteed precision beyond basic validation
Always review results before using them in important contexts.
About this tool
This tool helps you perform quick utility operations directly in your browser. It runs entirely in your browser without sending data to a server.
You can use this tool when handling simple tasks without installing additional software. The results should be interpreted as a processed output based on your input data.
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.