Leap Year Calculator

Check if a year is a leap year.

Year

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Leap year?

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Days in the year—

Next leap year—

How it works

A leap year calculator checks whether a given year has an extra day, 29 February, tells you whether that year runs to 365 or 366 days, and points to the next leap year ahead. Leap years exist to keep the calendar aligned with the Earth's orbit, which takes about 365.2422 days, so an extra day roughly every four years stops the seasons from drifting against the dates over time. The rule is not simply "every fourth year." A year is a leap year if it is divisible by four, but century years are an exception: they are leap years only when also divisible by 400. So 2000 was a leap year while 1700, 1800 and 1900 were not, and 2100 will not be. This 400-year correction fine-tunes the average calendar year to 365.2425 days, extremely close to the true solar year, and is exactly the subtlety people miss when counting by hand. Knowing whether a year is a leap year matters for anyone computing durations, interest on a daily basis, project schedules or birthdays on 29 February. A leap year calculator settles the question instantly and, by also giving the day count and the next leap year, helps with planning that has to account for the occasional 366-day year rather than assuming every year is the same length.

Formula

Leap year if divisible by 4, except centuries, which must be divisible by 400

A year qualifies as a leap year when it is divisible by 4, with one exception: years divisible by 100 are not leap years unless they are also divisible by 400. That layered test makes the average calendar year 365.2425 days, matching the solar year to within half a minute. A leap year therefore has 366 days and a common year 365, and the next leap year is found by stepping forward until the same test passes.

Source:ISO 8601 / Gregorian calendar

We review all our tools from time to time to ensure accuracy.

Worked example

Year:2026

2026 is not a leap year, so it has 365 days; the next leap year is 2028.

How to use this calculator

1
Enter your values
Enter year.
2
Adjust the options
Fine-tune any options to match your situation.
3
Read your result
Leap year? updates instantly as you type — no button to press.

Frequently asked questions

How do I know if a year is a leap year?

Check three conditions in order: if the year is not divisible by 4 it is common; if it is divisible by 4 but not by 100 it is a leap year; if it is divisible by 100 it is a leap year only when also divisible by 400. So 2024 is leap, 1900 is not, and 2000 is. The calculator applies this test for you and states the result plainly.

Why are some century years not leap years?

A plain four-year rule would over-correct, making the calendar year slightly too long and letting the seasons drift over centuries. Skipping the leap day in century years not divisible by 400 removes three leap days every 400 years, tuning the average year to 365.2425 days. That is why 1700, 1800 and 1900 were common years while 2000 kept its 29 February, and 2100 will again be a common year.

How many days are in a leap year?

A leap year has 366 days, one more than a common year's 365, with the extra day added as 29 February. This affects anything measured in days across the year: daily interest accrues for one more day, annual salaries spread over one more day, and a full-year span between two leap-day-adjacent dates covers 366 days. The calculator reports the exact day count for the year you enter.

What happens to 29 February birthdays?

People born on 29 February, sometimes called leaplings, have an actual birthday only in leap years. In common years they typically celebrate on 28 February or 1 March, and laws differ on which date counts for legal purposes such as coming of age. The calculator can tell you which upcoming years contain a 29 February so a leapling knows when their true birthday next falls.

When is the next leap year?

The calculator returns the next leap year after the one you enter by stepping forward until a year passes the leap-year test. Leap years usually occur every four years, so from 2026 the next is 2028, but the century rule can create an eight-year gap, as between 1896 and 1904, because 1900 was skipped. The result accounts for that exception automatically.