Leap Year Calculator
Check whether any year is a leap year. Enter a year and the calculator tells you yes or no, explains why under the real 4, 100 and 400 rule, shows how many days the year has, and lists the previous and next leap years. Free and instant in your browser.
Check whether a year is a leap year and see why. Enter any year for a yes or no answer, the 4, 100 and 400 rule that decides it, the number of days in that year, and the nearest leap years on either side. It answers is it a leap year for this year, a birth year or any year you type.
- Leap-year accurate
- 100% free
- No sign-up, no app
- Instant as you type
- Works offline after first load
How to use it
- 1
Enter a year
Type any year from 1 to 9999, such as a birth year or an upcoming one.
- 2
Read the answer
See whether it is a leap year and the rule that decides it.
- 3
See the nearby leap years
Check the previous and next leap years, plus the day count for the year you entered.
When it comes in handy
February planning
Find out whether a given February has 28 or 29 days before booking or scheduling.
Homework and teaching
Explain the 4, 100 and 400 rule with a worked example for any year.
Birthday checks
See whether a 29 February birthday falls in a real leap year.
Instant, accurate & 100% in your browser
The calculation runs right here in your browser, counting the real calendar so leap years and month lengths come out right. Nothing you type is sent to a server, there is no sign-up and no limit, and once the page has loaded it keeps working even with no connection.
Frequently asked questions
- What makes a year a leap year?
- A year is a leap year if it divides evenly by 4, except for century years, which must also divide by 400. So 2024 and 2000 are leap years, but 1900 and 2100 are not. This keeps the calendar lined up with the length of the solar year over the long run.
- Why is 1900 not a leap year but 2000 is?
- Both divide by 4 and both are century years, so the 400 rule decides. 2000 divides by 400, so it stays a leap year. 1900 does not divide by 400, so it loses its leap day. The 400 rule removes three leap days every four centuries to keep the calendar accurate.
- When is the next leap year?
- Leap years fall on years divisible by 4, skipping century years that are not divisible by 400. So after 2024 the next leap years are 2028, 2032 and 2036, and February gains a 29th day each time. Enter any year and the calculator lists the previous and next leap years for you.
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