# Leap Years Calculator. It also calculates the last leap year that was before a year and the next leap year that is after a year. The leap year algorithm. A leap year has 366 days, one extra day (Feb 29) over a normal year. There are 97 leap years every 400 years

## Is it a leap year? The last and the next leap year, before and after the year

### The leap year algorithm. The three conditions to check in order to know whether a year is a leap or a common one:

#### 1) A year that is divisible by 4 (no remainder when divided by 4) is a leap year.

#### 2) But if the year is also divisible by 100 (no remainder when divided by 100), it's not a leap year, unless....

#### 3) ... Unless it's divisible by 400 (no remainder when divided by 400).