why does February have 28 days?

We tend to believe that the division of the year into months according to the Gregorian calendar, which is used by almost everyone, is somehow set in stone, but this is not the case.

The Julian calendar, which was still in use in Turkey as recently as 1927, came before the Gregorian calendar, which itself came before the Roman calendar.

The latter previously used lunar cycles to split the entire year—from March to December—into 10 months, each of which had either 29 or 31 days. The first few months of the year were simply left unidentified.

It wasn't important because crops couldn't be sown or harvested during this time.

Eventually, to ensure that the calendar encompassed the entire year, the Roman monarch Numa Pompilius introduced two "new" months, January and February.

Because the Romans thought even numbers unlucky, there were always 29 or 31 days and never 30.

Regrettably, 12 multiplied by any odd integer always results in an even number. There must be one month with an even number for the number of days on the calendar to equal 365 in a year. Since the Romans honoured their dead throughout this month, February was selected to have 28 days.

They probably reasoned that there isn't much worse luck than being dead, so what harm could it possibly do?

The calendar was later modified by Julius Caesar to follow the'movements' of the Sun rather than the lunar cycle, and his Julian calendar was itself fine-tuned in 1583 by Pope Gregory XIII to create the Gregorian calendar we use today.

Yet, February, with its unusual 28-day length, managed to endure all these alterations. Unless it happens to be a leap year, in which case it naturally gains a full extra day.

The Gregorian calendar used today has months that are at least 28 days long. If not for February, that number would be a beautifully rounded 30. Every month on the calendar except the second has at least 30 days, while February only has 28. (and 29 on a leap year).

Why, therefore, are the month lengths on the most widely used calendar in the world so inconsistent?

And why does February continue to have the fewest days?

Put the Roman superstition to blame.

The first Roman calendar, the earliest forerunner of the Gregorian calendar, differed noticeably from later iterations in that it had 10 instead of 12 months. The original 10 months were expanded to 11 by the Roman monarch Numa Pompilius in order to perfectly align the calendar with the lunar year. The former calendar had 304 days in all, divided into 6 months of 30 days and 4 months of 31. Even numbers, according to ancient Roman tradition, were unlucky, thus Numa deliberately avoided using them in his calendar. Each of the 30 months was reduced by one day to become 29.

He now had 56 days to deal with because the lunar year is 355 days long (really, it is 354.367, but naming it 354 would have rendered the whole year unlucky!). Ultimately, at least 1 of the 12 months had to have an even number of days. This is due to a straightforward mathematical truth: any even number of odd numbers, such as twelve months, will always add up to an even number, despite his desire for the aggregate to be odd. Therefore Numa chose February as the unlucky month to have 28 days, a month that would host Roman rites honouring the dead.

Have you ever wondered why February only has 28 days as opposed to other months having 30 or 31? This has been the case for more than 2,700 years.

The 304-day ancient Roman calendar had March as the first day and finished in December.

It was based on a former, ten-moon-long lunar calendar. The remaining days of the year—roughly 61 of them—took place in the winter but weren't noted on the calendar.

In order to match the calendar with the lunar year and because 304 is an even number, which the Romans believed to be inauspicious, Numa Pompilius, the new king of Rome, added January and February.

There were 355 days in the new calendar. Except for February, which had 28 days, all the other months had an unequal number of days, either 29 or 31.

Due to Roman ceremonies honouring the deceased, February may have been selected as the "unlucky" month.

The calendar was still off, though. The Roman calendar was roughly 10 days shorter than the solar year because, as we all know, it takes the Earth slightly more than 365 days to orbit the sun.

Julius Caesar synchronised the calendar with the solar year in 46 BC and lengthened some of the months to reach 365 days.

Due to the fact that the year is somewhat longer than 365 days, February also acquired an additional day, but only once every four years, on a leap year.

Pope Gregory XIII altered the calendar in other minor ways throughout the 16th century.

Even if we now follow the so-called "Gregorian" calendar, one thing hasn't changed: February still has 28 days.