Leap years keep our calendar aligned with Earth's orbit by adding 29 February. Enter any year to check it instantly.
How to use the Leap Year Checker
- 1 Enter a year.
- 2 See whether it is a leap year and how many days it has.
Formula
Leap year if (year divisible by 4 AND not by 100) OR divisible by 400
Worked examples
Input: Divisible by 4, not by 100
Result: Leap year
366 days
Input: Divisible by 100, not by 400
Result: Not a leap year
365 days
Input: Divisible by 400
Result: Leap year
366 days
Why do we have leap years?
A solar year is about 365.2422 days. Adding a day every four years over-corrects slightly (365.25), so the Gregorian calendar skips three leap days every 400 years: century years are not leap years unless divisible by 400.
Upcoming leap years
2028, 2032, 2036, 2040, 2044 and 2048. The next skipped century leap year is 2100.
Frequently asked questions
Is 2100 a leap year?
No. It is divisible by 100 but not by 400.
How many leap years are in 400 years?
97 — which gives an average year of exactly 365.2425 days.
Do the rules apply to years before 1582?
Those years used the Julian calendar, where every fourth year was a leap year. This checker applies the Gregorian rules to all years (the proleptic Gregorian calendar).
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