Leap Year Calculator
About the Leap Year Calculator
February has twenty-eight days-except when it has twenty-nine, and knowing which years gain that extra day prevents spreadsheet errors, school project mistakes, and birthday jokes that land wrong for leap-day babies. This leap year calculator checks any year from 1 through 9999 against Gregorian rules: divisible by four is a leap year, except centuries unless divisible by four hundred. Enter a year, click once, and read whether it is a leap year plus supporting facts such as February day count and the rule path that decided the outcome. Historians validating Julian-to-Gregorian transitions, developers testing date libraries, teachers demonstrating calendar science, and anyone planning around February 29 use it as a quick authority.
How to use it
- Enter the year you want to evaluate (1-9999).
- Click Check leap year to apply Gregorian rules.
- Read yes/no result and February day count in details.
- Review which divisibility rule decided the outcome.
- Try adjacent years to see century boundary behavior.
Good to know
Results are calendar math from the dates you enter. Business-day tools skip weekends when they say so. They do not know local holidays unless the page says they do.
Frequently asked questions
Is the Leap Year Calculator free?
Yes. You can use it in your browser with no account and no download.
What makes a year a leap year in this calculator?
Gregorian rule: divisible by 4, except centuries unless divisible by 400.
Is 1900 a leap year?
No. Century years must be divisible by 400.
Is 2000 a leap year?
Yes. It is divisible by 400.
Will 2100 be a leap year?
No. 2100 fails the century exception.
Related
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