What Leap Year Checker does
A year is a leap year if it divides evenly by 4, unless it also divides by 100, in which case it must divide by 400 as well. Type a year and this page applies that test and tells you which step settled the answer: 2024 is a leap year because it divides by 4, 1900 is not because it divides by 100 but not 400, and 2000 is because it divides by 400. You also get the number of days in the year and in February, the three divisibility results, and the next and previous leap years. For reference, 2026 is a common year, and the next leap year after it is 2028.
Leap year or not: commonly checked years
Each row is the result this page gives for that year.
| Year | Leap year? | Why | Next leap year |
|---|---|---|---|
| 1400 | No | Divisible by 100 but not by 400 | 1404 |
| 1700 | No | Divisible by 100 but not by 400 | 1704 |
| 1800 | No | Divisible by 100 but not by 400 | 1804 |
| 1900 | No | Divisible by 100 but not by 400 | 1904 |
| 1978 | No | Not divisible by 4 | 1980 |
| 1982 | No | Not divisible by 4 | 1984 |
| 1984 | Yes | Divisible by 4, not a century year | 1988 |
| 1992 | Yes | Divisible by 4, not a century year | 1996 |
| 2000 | Yes | Divisible by 400 | 2004 |
| 2010 | No | Not divisible by 4 | 2012 |
| 2019 | No | Not divisible by 4 | 2020 |
| 2024 | Yes | Divisible by 4, not a century year | 2028 |
| 2025 | No | Not divisible by 4 | 2028 |
| 2026 | No | Not divisible by 4 | 2028 |
| 2028 | Yes | Divisible by 4, not a century year | 2032 |
| 2100 | No | Divisible by 100 but not by 400 | 2104 |
Years before 1582 are tested with today's rule. See the section on older dates below for what that means.
How to calculate a leap year: the rule in three steps
1. Year not divisible by 4: common year 2. Divisible by 4 but not by 100: leap year 3. Divisible by 100: leap year only if also divisible by 400 In code: (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0)
Work through the steps in order and stop at the first one that gives an answer. For 1992: 1992 / 4 = 498 with no remainder, and it does not end in 00, so step 2 makes it a leap year. For 2100: it divides by 4 and by 100, so step 3 applies, and 2100 / 400 = 5.25, so it is a common year. A quick check for step 1 is to look only at the last two digits: if they form a number divisible by 4, the whole year is divisible by 4.
Century years: which are leap years
Century years are where the simple every-four-years shortcut goes wrong. Only one in four is a leap year.
| Century year | Divisible by 400 | Result | Days in February |
|---|---|---|---|
| 1500 | No | Common year | 28 |
| 1600 | Yes | Leap year | 29 |
| 1700 | No | Common year | 28 |
| 1800 | No | Common year | 28 |
| 1900 | No | Common year | 28 |
| 2000 | Yes | Leap year | 29 |
| 2100 | No | Common year | 28 |
| 2200 | No | Common year | 28 |
| 2300 | No | Common year | 28 |
| 2400 | Yes | Leap year | 29 |
List of leap years from 1904 to 2096
Every fourth year between 1901 and 2099 is a leap year, with no exceptions, because the only century year in that span is 2000 and it divides by 400.
- 1904 to 1920: 1904, 1908, 1912, 1916, 1920
- 1924 to 1940: 1924, 1928, 1932, 1936, 1940
- 1944 to 1960: 1944, 1948, 1952, 1956, 1960
- 1964 to 1980: 1964, 1968, 1972, 1976, 1980
- 1984 to 2000: 1984, 1988, 1992, 1996, 2000
- 2004 to 2020: 2004, 2008, 2012, 2016, 2020
- 2024 to 2040: 2024, 2028, 2032, 2036, 2040
- 2044 to 2060: 2044, 2048, 2052, 2056, 2060
- 2064 to 2080: 2064, 2068, 2072, 2076, 2080
- 2084 to 2096: 2084, 2088, 2092, 2096
Why leap years exist, and why century years are skipped
The seasons repeat every 365.2422 days or so, not every 365. A calendar with a fixed 365 days would slip against the seasons by about a day every four years. Adding 29 February every fourth year, as the Julian calendar did from 45 BC, brings the average year to 365.25 days. That is slightly too long, by roughly 11 minutes a year, which adds up to a full day about every 128 years.
By the 1500s the calendar had drifted about ten days. The Gregorian reform of 1582 removed those days, so that Thursday 4 October was followed by Friday 15 October, and dropped three leap days in every 400 years to stop the drift returning. That is the century rule: 1700, 1800 and 1900 lost their leap day, 2000 kept it.
The result is 97 leap years in every 400 years, which is 100 years divisible by 4, minus 4 century years, plus the 1 that divides by 400. The average calendar year is therefore 365.2425 days, close enough to the seasons that the error takes around 3,000 years to reach one day.
Years before 1582 and the Julian calendar
This page applies the Gregorian rule to every year from 1 to 9999. For years before the Gregorian calendar was adopted, that is a back-projection, and it can disagree with what people living at the time recorded.
Under the Julian calendar every year divisible by 4 was a leap year, with no century exception. So 1400 and 1500 really did have a 29 February in the countries using that calendar, even though the result here is Common year. The same applies to 1700 in Britain and its colonies, which did not switch until 1752, and to 1900 in Russia, which switched in 1918.
If you are checking a date in a historical record, find out which calendar the place was using in that year. For anything from the 20th century onwards in most of the world, and for all software that follows ISO 8601, the Gregorian result shown here is the right one.
How to get your result
- 1
Type a whole number from 1 to 9999 in the Year field.
- 2
Read the heading of the result, Leap year or Common year, and the sentence under it that names the part of the rule that applied.
- 3
Check Details for Days in year, Days in February, and the Divisible by 4, Divisible by 100 and Divisible by 400 results.
- 4
Use Next leap year, and the previous one shown beneath it, to find the leap years on either side.