Why does February have 28 days?

Why does February have 28 days?

Have you ever wondered?

2/13/2024 | Angela Whitlock, CSRA

Have you ever wondered why February has 28 days (and 29 each leap year), or how the decision was made?  

Well, the answer involves quite a bit of math and ancient Roman superstitions.  

It all began with an ancient Roman King from 700 BCE, Numa Pompilius, who sought out to sync the Roman calendar with the Lunar year.  


The first Roman calendar originally consisted of ten months instead of twelve, with six of those months having 30 days and four of them having 31, for a total of 304 days in a year. The Lunar year, however, consists of roughly 355 days. Numa was dealing with a 51-day difference between the Roman calendar and the Lunar year and had quite a bit of restructuring to do as a result. 

Numa also wanted to avoid having even numbers in his revision of the calendar, due to Roman superstition that classified even numbers as unlucky. To do this, Numa first subtracted a day from each of the 30-day months of the original Roman calendar to make them all odd-numbered with 29 days. Now, he had 56 days left instead of 51. 


Then, he decided to add January and February at the beginning of the calendar, which shifted March from the first month of the calendar to the third month, and is also why October (from the Latin word Octo, translated to eight) is tenth month of the year instead of the eighth.  

In order for the calendar to add up to 355 days, Numi knew that at least one month had to contain an even number of days. He chose February, which was originally a month for hosting Roman rituals that honored the dead, as the unlucky month with an even number of 28 days.  


Numerous changes to the calendar have taken place since Numa’s reign. The Julian calendar, which takes its name from Julius Cesar, was proposed in 46 BCE. It was a solar calendar of 365 days with the addition of a leap day. The leap day was added so that the calendar would line up with the sun. However, this addition did not fully resolve the calendar’s issues.  

The Julian calendar was replaced by the Gregorian calendar and went into effect in 1582. It was issued by Pope Gregory XIII. Its main difference from the Julian calendar involved spacing of leap years in a slightly different way to match the calendar year more accurately with the solar year to total 356.2425 days (instead of 365.25 days like the Julian calendar). This change fixed a drift issue in the Julian calendar in respect to equinoxes, which has importance in Christian churches due to its connection to Easter. It also solidified February 29th as the official leap day every four years.  

Despite these alterations, February has remained consistently at 28 days as the second month of the year since around 700 BCE, and we have Numa Pompilius to thank.  


Sources for this article from: Encyclopedia Brittanica (online), United States Naval Conservatory (online), CBSNews.com, MentalFloss (online) and Wikipedia.  

Image credit: Unsplash