Leap Year Checker
Is it a leap year? Instant answer with the reason why, plus the leap years around it.
- Previous leap year
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- Next leap year
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Fast, easy and free — your answer appears as you type, and whatever you enter stays on your device.
Type a year and get an instant yes or no — with the rule that decided it spelled out, and the nearest leap years either side. The century exception (1900 was not one, 2000 was) is where every home-made check goes wrong.
How to use it
- Type a yearThis year is preloaded; any year from 1 to 9999 works.
- Read the verdictYes or no, with 365 or 366 days and February's length.
- See the reasonThe exact rule that applied — divisible by 4, the century exception, or the 400-year exception to the exception.
A 2,000-year rounding correction
Leap years exist because Earth ignores our calendar: a trip around the sun takes about 365 days and 6 hours, minus 11 minutes. Julius Caesar's calendar handled the 6 hours with a day every 4 years; the leftover 11 minutes accumulated for 16 centuries until dates had drifted 10 days against the seasons. The Gregorian fix of 1582 was surgical — cancel the leap day in centuries not divisible by 400 — and the tool's "reason" line is that fix in action.
Where the naive check bites
Divide-by-4 works for every year anyone alive has experienced except 1900, which is exactly what makes it dangerous: code and mental arithmetic both pass all recent tests and fail on the exceptions. Spreadsheets famously treat 1900 as a leap year to this day for compatibility. If you are validating dates in software, this is the test set: 2024 yes, 2023 no, 2000 yes, 1900 no, 2100 no. Every date tool on this site is built against those five, and this page lets you check any year the same way.
Years you check stay on your device, like everything else here.
Questions people ask
What makes a year a leap year?
Divisible by 4 — unless it is a century, in which case it must divide by 400. So 2024 yes, 2025 no, 1900 no, 2000 yes. Three rules stacked, and the tool tells you which one decided your year.
Why do centuries get special treatment?
Because a year is really 365.2422 days, not 365.25. Adding a day every 4 years overshoots slightly, so the Gregorian calendar cancels three leap days every 400 years by skipping the centuries that do not divide by 400. The result drifts only about one day in 3,000 years.
Is 2100 a leap year?
No — it divides by 100 but not by 400, so it follows 1900's pattern rather than 2000's. Software written today with a naive divide-by-4 check will quietly corrupt dates in 2100; some of it will still be running.
When is the next leap year?
The tool shows the nearest one in each direction for whatever year you enter. From 2026, the next is 2028.
What happens to people born on 29 February?
They age normally and celebrate on 28 February or 1 March in common years — legally, most places treat 28 February as the birthday. Our age calculator handles the arithmetic for them correctly.
Why does this tool exist when the rule is three lines?
Because the rule people remember is one line — divide by 4 — and the two forgotten lines produce wrong answers precisely on the memorable years like 1900 and 2100. A checker with the reason attached also settles arguments faster than a rule recited from memory.