Reason why February is the only month which has 28 days

Thirty days has September, April, June and November have thirty days. All the rest have thirty-one, except for February... but, um, no one can ever remember the rest of the song.

Yep, most of us know that February is the only month in the year with 28 days – or 29 days if it’s a leap year - but the details often escape us.

It's something to do with the earth’s rotation around the sun, right? Well, kind of, but there’s also a bit more to it. Time for a history lesson!

You see, the 28 days of February date back to Numa Pompilius, the second king of Rome.

According to the Indianapolis Children’s Museum, before his reign, Rome’s lunar calendar was just 10 months long, beginning in March and ending in December.

INTERFOTO/Alamy Stock Photo

“At the time, Romulus, the first king of Rome, and his people found the time between December and March to be unimportant because it had nothing to do with the Harvest,” the museum’s website explains.

“When Numa Pompilius took reign, he decided to make the calendar more accurate by lining it up with the year’s 12 lunar cycles.

“The new 355-day year needed two additional months to make up for the lost time. So he added January and February to the end of the calendar.”

But what about the shorter month?

The museum continues to say that Romans believed even numbers were ‘unlucky’, meaning each month had an odd number of days, alternating between 29 and 31.

“But, in order to reach 355 days, one month had to be an even number,” it continues.

“February was chosen to be the unlucky month with 28 days.”

It’s believed this choice may be down to the fact that Romans honoured the dead and performed rites of purification in February – the word ‘februare’ meaning ‘to purify’ in the dialect of the ancient Sabine tribe.

Jerome/Alamy Stock Photo

“After a few years of using the Numa Pompilius’ new 355-day calendar, the seasons and months began to fall out of sync,” the Indianapolis Children’s Museum says.

“In an attempt to realign the two, the Romans added a 27-day leap month as needed. If Mercedonius was used, it began on February 24.”

Because the leap month was ‘inconsistent’, there were obviously still flaws with this idea.

"In 45 B.C., Julius Caesar commissioned an expert to create a sun-based calendar like the one the Egyptians used,” the museum goes on.

“The Julian Calendar added a little more than 10 days to each year, making each month either 30 or 31 days long, except for February.

“To account for the entire 365.25 day-long year, one day was added to February every four years, now known as a ‘leap year.’

“During most years, this left February with just 28 days.”

And if that wasn’t confusing enough, the year 46 BCE reportedly had to be 445 days long to get Rome on track with the Julian Calendar... how's that for a head f**k?!