How often do the leap years occur in the calendar?
Nearly once every four years, more exactly, 97 leap years in every cycle of 400 years.
Nearly once every four years is a leap year, and these years must be multiples of 4. More precisely, as you can calculate below, by using the algorithm, or by studying the list with all the leap years between 1582 and 4818 (link to this list below on this page), leap years happen in a cycle of 97 years out of every 400.
Leap years algorithm.
Every year that is evenly divisible by 4 is a leap year, except for years that are evenly divisible by 100, but these years are leap years if they are evenly divisible by 400:
- 1) A leap year is divisible by 4 (evenly divided by 4, having a zero remainder when divided by 4).
- 2) Except if it's divisible by 100 (evenly divided by 100, having a zero remainder when divided by 100) then it isn't a leap year.
- 3) But even for the previous step above, if it's also divisible by 400 (evenly divided by 400, having a zero remainder when divided by 400) then it's a leap year.