How Does a Leap Year Work?

A leap year gives us an extra day to keep our calendar in line with how the Earth moves around the Sun.

Imagine you and your friend are playing a game where you take turns counting steps around a circular track. Every time you finish one full circle, that's like a year. But sometimes, you're just a little bit ahead, not quite done yet. That’s why we add an extra day every few years: February gets 29 days instead of 28!

The Earth takes about 365 days and 6 hours to go all the way around the Sun. That extra time adds up over the years, like a slow drip from a water glass.

If we didn’t add that extra day, our calendar would slowly get out of sync with the seasons. Spring might start in April one year, and then March the next!

Most years have 365 days. But every 4 years, we add a leap day, February 29. That helps us catch up on that extra time.

However, there's a little trick: if the year is divisible by 100, it’s not a leap year, unless it’s also divisible by 400. So 2000 was a leap year, but 1900 wasn’t!