BYTETOOLS

Leap Year Checker

Check whether any year is a leap year, understand the divisible-by-4/100/400 rule, and see the next and previous leap years. Free and fully in-browser.

Yes — 366 days
Is 2028 a leap year?

2028 is divisible by 4 and is not a century year, so it is a leap year of 366 days.

2024, 2020, 2016
Previous leap years
2032, 2036, 2040
Next leap years

What is the Leap Year Checker?

The ByteTools Leap Year Checker instantly tells you whether a given year has 366 days. Type any year and it confirms leap or common, explains exactly which part of the Gregorian rule applies, and lists the surrounding leap years so you can plan ahead or look back.

  • Instant leap-year yes/no for any year
  • Plain-English explanation of the exact rule applied
  • Lists the next and previous leap years
  • Correctly handles century years (1900 no, 2000 yes)
  • Works for historical and far-future years
  • 100% in-browser — private and offline-ready

How to use the Leap Year Checker

  1. 1

    Type the year you want to check (or click This year).

  2. 2

    See instantly whether it is a leap year or a common year.

  3. 3

    Read which part of the divisible-by-4/100/400 rule decided it.

  4. 4

    Browse the next and previous leap years listed below.

About the Leap Year Checker

The ByteTools Leap Year Checker instantly tells you whether a given year has 366 days. Type any year and it confirms leap or common, explains exactly which part of the Gregorian rule applies, and lists the surrounding leap years so you can plan ahead or look back.

Leap years keep our calendar aligned with Earth's orbit by adding February 29 every four years — but with exceptions on century years. The rule is: a year is a leap year if it is divisible by 4, except centuries, which must also be divisible by 400. So 2000 was a leap year while 1900 and 2100 are not.

The check runs entirely in your browser with JavaScript. Nothing is uploaded, so it is a fast, private reference whenever you need to confirm a February 29 or a 366-day year.

Frequently asked questions

What is the rule for a leap year?

A year is a leap year if it is divisible by 4, unless it is a century year (divisible by 100), in which case it must also be divisible by 400. So 2024 and 2000 are leap years, but 1900 and 2100 are not.

Why isn't every year divisible by 4 a leap year?

A solar year is about 365.2422 days, so adding a day every 4 years slightly overcorrects. Skipping the leap day on most century years — keeping it only when divisible by 400 — trims the excess and keeps the calendar accurate for millennia.

Was 2000 a leap year?

Yes. 2000 is divisible by 400, so it kept February 29 despite being a century year. In contrast 1900 and 2100 are divisible by 100 but not 400, so they are common years with 365 days.

How many days are in a leap year?

A leap year has 366 days because February gains a 29th day. A common year has 365 days. This extra day is why day-of-year numbers from March onward shift by one in leap years.

When is the next leap year?

Leap years generally occur every four years — 2024, 2028, 2032 and so on. Enter any year in the checker and it lists the next and previous leap years so you can see the pattern around your date.

Guides for Leap Year Checker

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