How to Calculate Leap Year and Why it Exists in the First Place

6. How do you calculate a leap year?

In order to work out whether or not a year is a leap year, the simplest way is to see if the year can be evenly divided by 4. So 1996? A leap year. 1745? Not a leap year. This rule works on every year except the new century years.

These are only considered to be leap years if they can be evenly divided by 400. So 1600? Divisible by both 4 and 400, and therefore a leap year. 1900? Divisible by 4, but not by 400, so not a leap year. 2020 is the next leap year.