Leap Year Calculator
This leap year calculator tells you whether any year from 1 to 9999 is a leap year, and why: a year divisible by 4 is a leap year, except century years that are not divisible by 400, so 2000 was a leap year and 2100 will not be. It shows the next and previous leap years, lists every leap year in a range (2000 to 2100 has 25), and counts how many real birthdays someone born on 29 February has had. A historical setting uses the Julian calendar’s every-fourth-year rule up to 1582, the year the Gregorian calendar replaced it. Download any range as a CSV.
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Check a year
Born on 29 February?
List leap years
Everything runs in your browser and only your settings are remembered in this browser. Gregorian rule (as the US Naval Observatory states it): years divisible by 4 are leap years, except century years not divisible by 400. The historical setting uses the Julian rule (every fourth year) up to 1582, when 4 October was followed by 15 October in the countries that switched first; Britain and its colonies switched in September 1752.
How to check a leap year
- Type a year: the answer and the reason appear at once, with the next and previous leap years.
- Choose the Gregorian rule for every year, or the historical setting with the Julian rule up to 1582.
- Set a range to list its leap years, and download them as a CSV.
- For a 29 February birthday, type the birth year and a later year to count the real birthdays.
What you can use it for
- Checking whether a year has 29 February
- Counting birthdays for someone born on a leap day
- Listing leap years for a spreadsheet or a lesson
- Checking date code that handles 29 February
- Working out when the next leap year is
Leap years from 2000 to 2100
2000, 2004, 2008, 2012, 2016, 2020, 2024, 2028, 2032, 2036, 2040, 2044, 2048, 2052, 2056, 2060, 2064, 2068, 2072, 2076, 2080, 2084, 2088, 2092, 2096. That is 25 leap years; 2100 is not one.
| Leap year | 29 February falls on a |
|---|---|
| 2028 | Tuesday |
| 2032 | Sunday |
| 2036 | Friday |
| 2040 | Wednesday |
| 2044 | Monday |
| 2048 | Saturday |
| 2052 | Thursday |
| 2056 | Tuesday |
| 2060 | Sunday |
The rules
Gregorian calendar: a year divisible by 4 is a leap year, except a century year, which must also be divisible by 400 (the rule as the US Naval Observatory states it). Julian calendar: every year divisible by 4. The tool checks every year from 1 to 9999 against the rule, and we checked its answers against a second, independent implementation for all 9,999 years.
Leap years on the calendar
29 February on a printable month: February 2028 Calendar and February 2032 Calendar. The whole leap year: 2028 Calendar. Any month of any year: Calendar Maker.
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See all free tools →Frequently asked questions
Is 2027 a leap year?
No. 2027 is not divisible by 4, so February 2027 has 28 days and the year has 365. The next leap year is 2028; the previous one was 2024.
What is the rule for leap years?
In the Gregorian calendar a year is a leap year if it is divisible by 4, except century years, which must be divisible by 400. So 1600 and 2000 were leap years, and 1700, 1800, 1900 and 2100 are not.
Was 1900 a leap year?
No. 1900 is a century year that is not divisible by 400, so it had no 29 February in the Gregorian calendar. 2000 was a leap year because it is divisible by 400.
How many leap years are there between 2000 and 2100?
25: every fourth year from 2000 to 2096. 2100 is not a leap year.
How many birthdays does someone born on 29 February have?
One every leap year. Someone born on 29 February 2000 has had 6 real birthdays by the end of 2027 (2004 to 2024) and turns 28 on the next one, 29 February 2028.
What was the Julian rule?
The Julian calendar made every fourth year a leap year, with no century exception. The Gregorian calendar replaced it in 1582: 4 October 1582 was followed by 15 October, so in the historical setting 1582 has 355 days. Britain and its colonies switched in September 1752.
Why do we have leap years?
The seasons repeat about every 365¼ days, so an extra day every fourth year keeps the calendar in step. 365.25 days is slightly too long, so the Gregorian rule drops three leap days every 400 years: 97 leap years in 400 gives an average of 365.2425 days.
Can I download a list of leap years?
Yes. Set the range and download the CSV: one row per year with whether it is a leap year, its number of days and February’s length.
Is my information uploaded?
No. Everything is worked out in this browser, and the files you download are made on your device.