2100 is not a leap year
- Year
- 2,100
Result2100 is not a leap year. It is divisible by 100 but not by 400, which is the exception most people forget.
divisible by 100 but not 400: the century exception
Open this exampleDate & Timedates
Leap Year Checker
Whether a year is a leap year, including the century rule that catches people out. 1900 was not a leap year and 2000 was.
Also called: is it a leap year, leap year test.
Result
2100 is not a leap year. It is divisible by 100 but not by 400, which is the exception most people forget.
2100 is not a leap year. It is divisible by 100 but not by 400, which is the exception most people forget.
Leap year (1 = yes)
0
Days in the year
365
Next leap year
2,104
Method and background
How this is calculated
A tropical year is about 365.2422 days, so adding a day every four years overshoots slightly. Skipping the century years corrects too far, and restoring every fourth century corrects back. The remaining error is about one day in 3,200 years.
leap = (year %% 4 == 0 and year %% 100 != 0) or year %% 400 == 0- y
- The year
Worked examples
Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.
2000 was
- Year
- 2,000
Result2000 is a leap year, so it has 366 days.
divisible by 400: the exception to the exception
Open this example2024 was
- Year
- 2,024
Result2024 is a leap year, so it has 366 days.
ordinary four-year rule
Open this example