Check whether any year is a leap year, with the rule explained and the next leap years listed.
A leap year exists because the Earth does not orbit the Sun in a round number of days. One orbit takes about 365.2422 days, so a fixed 365-day calendar drifts by almost six hours a year — a full day every four years, and eventually Christmas in the middle of summer. Adding 29 February every four years fixes most of that drift, but slightly overcorrects it, which is why the Gregorian calendar adds two exceptions on top of the simple rule. This checker applies all of it to any year you type and shows the reasoning instead of just a yes or no.
The rule is short: a year is a leap year when it is divisible by 4, except years divisible by 100, unless they are also divisible by 400. That is why 2024 is a leap year, 1900 is not, and 2000 is — the case that broke a famous amount of software. Skipping three leap days every 400 years brings the average calendar year to 365.2425 days, within half a minute of the real solar year, which is close enough to stay accurate for roughly three thousand years. The tool traces those exact divisions for the year you enter, tells you whether February has 28 or 29 days, and lists the next ten leap years from there.
It is the fast answer to everyday questions: whether a contract year has 365 or 366 days, when the next 29 February falls for someone born on it, which year a school project should use as an example, or why a date calculation in a spreadsheet is one day off. Keep in mind that the rule shown here is the Gregorian one, adopted from 1582 onwards and at different dates in different countries; for earlier years the Julian calendar simply made every fourth year a leap year. The check runs entirely in your browser and nothing you type is sent anywhere.
A year is a leap year when it is divisible by 4, except years divisible by 100, unless they are also divisible by 400. So 2024 and 2000 are leap years with 366 days, while 1900 and 2100 are common years with 365. The three skipped leap days per 400 years bring the average calendar year to 365.2425 days, against a solar year of about 365.2422 days.
Both are divisible by 4 and by 100, so both are century exceptions — but only 2000 is also divisible by 400, which puts the leap day back. 1900, 1800 and 2100 are common years of 365 days.
Every four years, minus three exceptions in every 400 years. A 400-year cycle therefore has 97 leap years rather than 100.
It has 366 days, because February gains a 29th day. A common year has 365.
They only get a calendar birthday every four years, and most legal systems treat 28 February or 1 March as the equivalent date in common years — the rule varies by country.
Not exactly. The Gregorian calendar started in 1582 and was adopted at different dates around the world; before that the Julian calendar made every fourth year a leap year with no century exception. This tool always applies the Gregorian rule.
No. The check is a couple of divisions performed in JavaScript on your device, with no network request involved.
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