Leap Year Checker
Type any year to see whether it is a leap year under the Gregorian calendar, how many days its February has, and the nearest leap years on either side.
Reviewed by the CalcCafe editorial team · Last updated 18 July 2026 · How we test our tools
Example
Check the year 2026. It is not divisible by 4 (2026 ÷ 4 = 506.5), so 2026 is not a leap year and its February has 28 days. The next leap year is 2028 and the previous one was 2024. The century exception matters too: 1900 was not a leap year (divisible by 100 but not by 400), while 2000 was (divisible by 400).
How it works
The checker applies the Gregorian calendar rule in three steps: a year is a leap year if it is divisible by 4 — unless it is also divisible by 100, in which case it is a common year — unless it is further divisible by 400, in which case it is a leap year after all. Leap years have a 29-day February and 366 days in total. The next and previous leap years are found by stepping year by year from your input and applying the same rule.
Good to know
Leap years exist because the calendar and the Earth disagree. One trip around the Sun — the tropical year — takes about 365.2422 days, roughly a quarter-day more than a 365-day calendar year. Without correction the calendar would drift about one day every four years, and within a few centuries the seasons would slide visibly across the calendar. Adding a 366th day roughly every fourth year absorbs most of that drift and keeps June in summer and December in winter for the northern hemisphere.
A leap day every four years slightly overcorrects, because 0.25 is a touch more than 0.2422. The old Julian calendar made exactly that error, gaining about three days every four centuries; by the 16th century the accumulated drift was around ten days, which is why the Gregorian reform of 1582 both dropped days from the calendar and refined the rule. The fix is the century exception: years divisible by 100 are not leap years unless they are also divisible by 400. That is why 1700, 1800 and 1900 were common years while 1600 and 2000 were leap years, and why 2100 will skip the leap day too.
People born on 29 February — often called leaplings — get a true calendar birthday only every four years, but the law does not wait. Most jurisdictions treat 1 March as the legal birthday in common years for purposes such as driving or voting age, though some, New Zealand for example, use 28 February. Contracts and software that anniversary a 29 February date typically roll it to 28 February or 1 March in non-leap years, so it is worth knowing which convention your paperwork follows.
Do not confuse leap years with leap seconds. Leap years correct the calendar for the length of Earth's orbit; leap seconds are occasional one-second adjustments to atomic time (UTC) that compensate for irregularities in Earth's rotation. They are managed by entirely different rules and organisations, and no leap-year arithmetic involves them. Also note that the rule checked here is Gregorian — other calendars, such as the Hebrew or Islamic calendars, handle intercalation in completely different ways.
Frequently asked questions
What is the rule for deciding if a year is a leap year?
A year is a leap year if it is divisible by 4, except century years, which must be divisible by 400. So 2024 and 2028 are leap years, 2026 is not, 1900 was not a leap year, and 2000 was.
Why do century years like 1900 skip the leap day?
A leap day every four years overcorrects slightly, because the solar year is about 365.2422 days, not 365.25. Dropping the leap day in three out of every four century years keeps the calendar within about one day of the seasons over thousands of years.
When is the birthday of someone born on 29 February?
In common years, most jurisdictions treat 1 March as the legal birthday for age-based rights, while some, such as New Zealand, use 28 February. Socially, leaplings choose either date; their true calendar birthday returns every leap year.
Is my data uploaded anywhere?
No — this checker runs entirely in your browser. The year you type never leaves your device, and the tool works offline once the page has loaded.
People also ask
Is 2026 a leap year?
No. 2026 is not divisible by 4, so it is a common year with a 28-day February and 365 days. The previous leap year was 2024 and the next one is 2028.
Why does a leap year have 366 days?
Because the Earth takes about 365.2422 days to orbit the Sun. Adding one extra day, 29 February, roughly every fourth year keeps the calendar aligned with the seasons instead of drifting by about a day every four years.
Are leap seconds part of leap years?
No. Leap seconds are one-second adjustments occasionally added to atomic time (UTC) to track Earth's irregular rotation. They have nothing to do with the leap-year rule, which corrects the calendar for the length of Earth's orbit.
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Sources & references
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