Why February Only Has 28 and Sometimes 29 Days?

"Why does February have only 28 (and sometimes 29) days?" If you've ever wondered about the history and astronomy behind this quirky month, get ready to be fascinated by the answers.

Why February Only Has 28 and Sometimes 29 Days? [Click image to zoom]

February is a month that has always been a bit of an outlier in the Gregorian calendar, with only 28 days in most years and 29 days in leap years. But why exactly does February have only 28 days? The answer lies in a combination of ancient Roman history, the quirks of astronomy, and the decision-making of medieval European lawmakers.

To understand why February has 28 days, we have to go all the way back to the founding of Rome. The ancient Romans used a lunar calendar, which had 355 days in a year. However, this calendar had a major flaw: it didn't line up with the solar year, which is the amount of time it takes for the Earth to make one orbit around the sun. As a result, the Romans periodically had to add an extra month to their calendar to keep it in sync with the seasons.

In 46 BCE, Julius Caesar reformed the Roman calendar to align it with the solar year. He introduced the Julian calendar, which had 365 days in a year and included an extra day every four years to account for the fact that the solar year is actually 365.25 days long. However, he made a mistake when it came to February: he gave it 30 days, which was the same length as the months of April, June, September, and November. This meant that the year was slightly longer than 365.25 days, which threw the calendar off by about 11 minutes per year.

This error might not have been a big deal, except that it compounded over time. By the 16th century, the Julian calendar was off by about 10 days, which meant that the spring equinox was happening on March 11th instead of March 21st. This was a problem for the Catholic Church, which relied on the equinox to calculate the date of Easter.

To fix this problem, Pope Gregory XIII introduced the Gregorian calendar in 1582. This new calendar had the same number of days as the Julian calendar, but it made one important change: it omitted 10 days from the year 1582 to bring the calendar back into alignment with the seasons. It also introduced a new rule for leap years: a year is a leap year if it is divisible by 4, except for years that are divisible by 100 but not by 400. This rule eliminated the extra 11 minutes per year that had been throwing the calendar off, and it meant that the year was now almost exactly 365.25 days long.

So why does February have only 28 days? It's because Julius Caesar gave it that number, and subsequent lawmakers decided to stick with it. According to some theories, February may have been considered an unlucky month by the ancient Romans, which could be why it was given a shorter length. Another theory is that February was the month in which debts were settled, and a shorter month meant that people would have less time to pay up. Whatever the reason, February has been stuck with 28 days for centuries, and it doesn't look like that's going to change anytime soon.

Do you know how each month is assigned a specific number of day? Find out why!

Discover More