Type a year to see whether it is a leap year, which rule applies, how many days it has, and the next and previous leap years. You can also count the leap years between two years.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How the Leap year checker works
The calculator applies the Gregorian calendar rule:
- A year divisible by 4 is a leap year,
- except a year divisible by 100, which is not,
- unless it is also divisible by 400, in which case it is.
So 2024 and 2028 are leap years, 1900 and 2100 are not, and 2000 was. A leap year has 366 days and a February of 29 days. Other years have 365 days and a 28-day February.
The next and previous leap years are found by checking each year in turn. To count leap years between two years inclusive, it uses a closed formula: the number of leap years up to a year is the integer part of year ÷ 4, minus year ÷ 100, plus year ÷ 400, and the count is the difference between the two ends.
The rule is applied to every year from 1 to 9999. Before the Gregorian calendar was adopted (1752 in Britain and its colonies), the Julian calendar was used, so historic dates may differ.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Year | 2028 |
| Count leap years from | 2000 |
| to | 2100 |
Is 2028 a leap year?: Yes, a leap year
| Rule applied | 2028 is divisible by 4 and is not a century year, so it is a leap year. |
|---|---|
| Days in 2028 | 366 |
| February has | 29 days |
| Next leap year | 2032 |
| Previous leap year | 2024 |
| Leap years from 2000 to 2100 | 25 |
Tips and common mistakes
Remember the century exception: years such as 1900 and 2100 look like leap years but are not. Check the rule when you write date code or spreadsheets, since a simple divide-by-four test is wrong for century years. For anniversaries and birthdays on 29 February, check how a contract or system treats non-leap years. Use the range count to see how many leap days fall in a project or a time span, and add days for those.
Frequently asked questions
Is 2100 a leap year?
No. It is divisible by 100 but not by 400, so 2100 has 365 days and a 28-day February.
Why do we have leap years?
The Earth takes slightly longer than 365 days to orbit the Sun, so an extra day about every four years keeps the calendar in step with the seasons.
Was 2000 a leap year?
Yes. It is a century year, but it is divisible by 400, so it was a leap year with 366 days.