Why does February have fewer days?

11 months out of 12 in a year have at least 30 days – seven with 31 while four have 30. But February, the second month of the year, has either 28 days (common year) or 29 (leap year). You must have often wondered why this is the case, so we’ve tried to do a bit of explaining here.

The original Roman Calendar consisted of only 10 months, consisting of 30 and 31 days, with wintertime not part of the calendar. During the time of Numa Pompilius, the second king of Rome, as even numbers were considered bad luck in Ancient Rome, he removed one day from the even-numbered months.

In addition to that, he added two new months to the calendar – January and February. As he wanted to cover 12 lunar cycles, the year would consist of 355 days (it was supposed to be 354, but you already know that even numbers are bad luck). As there were 57 days that were to be added, 29 were given to January and 28 to February. According to Slate, this could be because February was the month when the dead were honored, and the festival of purification was held.

The problem that would arise with this calendar was that the earth takes a little more time (approximately 10 days) to revolve around the sun. To compensate for that, every second year, a leap month was added after February so that – on average over a few years – seasons remained consistent. While this led to an average of 366.25 days per year, which was closer to the amount of time the earth takes to revolve around the sun, it still wasn’t the correct number.

It was only a few centuries later that Julius Caesar introduced the 365-day solar calendar, after visiting Egypt where this was common practice. While he added 10 days across different months, he kept February as it was. But as the earth takes 365.2425 days to revolve around the sun, he introduced a 29th day every four years to ensure that the months always matched with seasons.

While it was very close to achieving its purpose, it did not do so completely as an average year in the Julian Calendar consisted of 365.25 days and not 365.2425. Centuries later, it was Pope Gregory XIII, who sanctioned a new calendar in 1582, in which three out of every four century years would not be a leap year. This gave rise to the Gregorian Calendar, which is the most widely used calendar in the world today.

References:

- https://slate.com/news-and-politics/2007/02/why-are-there-28-days-in-february.html

- https://ed.ted.com/best_of_web/MXwQDDs8