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Leap Year Calculator

Instantly check whether any year is a leap year.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Type any year into the field β€” it defaults to the current year, so you see an answer right away.
  2. 2.Read whether it is a leap year, along with the rule that decides it and the number of days that year has.
  3. 3.Check the previous and next leap years, plus the leap years listed nearby below the result.

About Leap Year Calculator

A leap year is a year with 366 days instead of the usual 365, adding a 29th day to February to keep the calendar in step with Earth's orbit around the Sun. Under the Gregorian calendar a year is a leap year when it is divisible by 4, with one exception: century years (those ending in 00) are leap years only when they are also divisible by 400. This leap year calculator applies that rule with pure arithmetic and tells you instantly whether the year you enter is a leap year, why, how many days it has, and the leap years immediately before and after it.

The full rule has three parts. First, if a year is not divisible by 4 it is a common year of 365 days, so 2023 and 2025 are not leap years. Second, if it is divisible by 4 but is not a century year, it is a leap year of 366 days, so 2024 and 2028 are leap years. Third, century years need the stricter test: 1900 and 2100 are divisible by 4 but not by 400, so they are common years, while 1600, 2000 and 2400 are divisible by 400 and are leap years. This is exactly why 2000 was a leap year but 1900 and 2100 are not, a distinction that ordinary 'divisible by 4' shortcuts get wrong.

The extra day always lands on February 29. A common year gives February 28 days; a leap year gives it 29. The correction exists because Earth takes about 365.2422 days to orbit the Sun. Adding one day every four years slightly overcorrects, so the calendar removes three leap days every 400 years by skipping the century years that are not divisible by 400, leaving 97 leap years in every 400-year cycle.

Common reasons to check a leap year include planning February 29 birthdays and anniversaries, calculating ages and date differences that cross a leap day, scheduling payroll and billing cycles, validating dates in spreadsheets and software, and settling trivia such as is 2100 a leap year. Alongside the yes-or-no answer, the tool shows the total days in the year, the number of days in February, the previous and next leap years, and a list of leap years nearby so you can see the pattern at a glance.

The calculator works for any whole-number year, including 0 and negative years under the proleptic Gregorian calendar (astronomical year numbering, where year 0 is 1 BC), because the divisibility rule holds for every integer. Everything runs in your browser, so nothing is uploaded and there is no signup or limit on how many years you check. To count the exact days between two dates, use a date difference calculator; to find which numbered day of the year a date falls on, use a day of year calculator; and to work out an age across leap years, use an age calculator.

Frequently asked questions

Is it a leap year this year?
The year field defaults to the current year, so the tool immediately answers is it a leap year for right now, showing yes or no, the reason, and whether the year has 365 or 366 days. Change the year and the answer updates as you type.
What is the rule for a leap year?
Under the Gregorian calendar a year is a leap year if it is divisible by 4, except for century years: a year ending in 00 is only a leap year when it is also divisible by 400. In short, divisible by 4 and (not divisible by 100, or divisible by 400). That single 100-versus-400 test is what separates leap years from common century years.
Why is 2000 a leap year but 1900 and 2100 are not?
All three are divisible by 4 and end in 00, so they hit the century-year exception. 2000 is also divisible by 400, so it stays a leap year, while 1900 and 2100 are not divisible by 400, so the rule skips them and they are common years of 365 days.
Is 2100 a leap year?
No. 2100 is divisible by 4 but it is a century year that is not divisible by 400, so under the Gregorian rule it is a common year with 365 days and February has 28 days. The next century year that is a leap year is 2400.
How often do leap years happen and how many days does one have?
A leap year has 366 days, with February 29 as the extra day. Leap years occur roughly every 4 years, but three century years are skipped every 400 years, giving 97 leap years per 400-year cycle. The tool lists the leap years nearby so you can see the spacing, including the 8-year gap around skipped century years like 1900 and 2100.

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