Why Does February Have 28 Days?

Every month gets 30 or 31 days — except February, which limps along with 28 and borrows a 29th when it can. The reason isn't astronomy. It's Roman superstition, plus a calendar that originally didn't bother counting winter at all.

A ten-month year

Rome's earliest traditional calendar, credited to Romulus, had just ten months, running from March to December — roughly 304 days. The dead of winter belonged to no month whatsoever; the count simply stopped after December and resumed in spring. (This is also why September, October, November and December are named "seventh" through "tenth" month — they once were.)

Numa's unlucky number

Around 700 BC, the reforming king Numa Pompilius added January and February to cover winter. Roman tradition held even numbers to be unlucky, so Numa's months got 29 or 31 days — but the arithmetic of a 355-day lunar year forced one month to be even. February, the month of ritual purification (februa), already associated with the dead, drew the short straw with 28 days. To stay aligned with the seasons, the Romans periodically inserted an extra month, Mercedonius — a messy system that officials happily abused to lengthen political terms.

Caesar tidies up — mostly

Julius Caesar's reform of 45 BC scrapped the extra month, distributed days to make the familiar 30/31 pattern, and set the year at 365 days with a leap day every four years. February kept its short count and became the natural home of the new leap day. (The old story that Augustus stole a day from February so August could match July is a mediaeval invention — the month lengths predate him.)

So February's 28 days are a 2,700-year-old superstition, fossilised in every calendar on Earth. Check whether this year grants it a 29th with the leap year calculator.