Leap Day: February 29, 2020

By Vigdis Hocken

A Leap Day, February 29, is added to the calendar during leap years. This extra day, also called Leap Year Day, makes the year 366 days long – not 365 days, like a common year.


Role reversal on leap day.

©iStockphoto.com/AntonioGuillem
When Is the Next Leap Day?

The next leap day is Saturday, February 29, 2020.

The last Leap Day was on Monday, February 29, 2016.
Why Add a Leap Day?

Leap days are needed to keep our calendar in alignment with the Earth's revolutions around the Sun.

It takes the Earth approximately 365.242189 days – or 365 days, 5 hours, 48 minutes, and 45 seconds – to circle once around the Sun. This is called a tropical year.

Without an extra, or intercalary, day on February 29 nearly every four years, we would lose almost six hours every year. After only 100 years, a calendar without leap years would be off by approximately 24 days in relation to fixed seasonal days such as the vernal equinox or the winter solstice.

Is There a Perfect Calendar?
Caesar Introduced Leap Years

Roman general Julius Caesar implemented the first leap day in his Julian Calendar, which he introduced in 45 BCE. A leap day was added every four years. At the time, leap day was February 24, and February was the last month of the year.
Too Many Leap Years

However, adding a leap day every four years was too often and eventually, in 1582, Pope Gregory XIII introduced the Gregorian Calendar. This calendar, which we still use today, has a more precise formula for calculation of leap years, also known as bissextile years.


Leap day as a concept has existed for more than 2000 years and it is still associated with age-old customs, folklore, and superstition. One of the most well-known traditions is that women propose to their boyfriends, instead of the other way around.

What's a Leap Second?
Leap Months

The ancient Roman Calendar added an extra month every few years to maintain the correct seasonal changes, similar to the Chinese leap month.