Leap Year Checker
Check whether any year is a leap year in the Gregorian calendar. Free and private, right in your browser.
Type in any year and instantly find out if it's a leap year (366 days, with February 29) or a common year - handy for building calendars, checking someone's real birthday count, or settling a Feb 29 debate.
How to use it
- Enter a year
- Hit check (or just watch it update)
- See if it's a leap year and why
Frequently asked questions
- What's the actual rule for leap years?
- A year is a leap year if it's divisible by 4 - except century years (like 1900), which are only leap years if divisible by 400. That's why 2000 was a leap year but 1900 wasn't, and 2100 won't be either.
- Why isn't every 4th year a leap year?
- A solar year is about 365.2422 days, not exactly 365.25, so adding a leap day every 4 years overcorrects slightly. Skipping the leap day in century years not divisible by 400 (1700, 1800, 1900, 2100...) keeps the calendar aligned over centuries.
- Does this work for years like 1 BC or negative years?
- Enter any calendar year as a positive number for AD/CE years - the tool applies the standard Gregorian rule. Historical years before 1582 (when the Gregorian calendar was adopted) technically followed the Julian calendar's simpler every-4-years rule instead.
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Nothing is uploaded
The file never leaves your device. There is no server to send it to, so there is nothing to leak, log, or subpoena.
- 2
No signup, no limits
No account, no email, no daily cap, no watermark, and no paid tier waiting behind the third file.
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Works offline
Load the page once and it keeps working with the network off, because all the work was always happening locally.