🖤When is the next Friday the 13th?

Try one of these too

Where the superstition came from

The two halves have long histories on their own and a short history together. Thirteen has been treated as an unlucky number for centuries, usually explained by the thirteen at the Last Supper; Friday carried its own weight in Christian Europe as the day of the Crucifixion. What is hard to find is any evidence that anyone combined them before the 19th century — folklorists looking for an older written trace keep coming back empty-handed.

The earliest widely cited appearance in English is a note in a biography of Rossini, who died on Friday 13 November 1868, remarking on the coincidence of the unlucky day and the unlucky number. In 1907 the Boston stockbroker Thomas W. Lawson published a novel called Friday, the Thirteenth, in which a trader brings down Wall Street by exploiting the superstition, and the date entered popular culture properly. The film series of 1980 onwards did the rest.

The story you may have heard about the Knights Templar is half true and half modern. The mass arrests really did take place on Friday 13 October 1307. The claim that the date became unlucky because of them appears nowhere until the 20th century, which is several hundred years too late to be the cause of anything.

What the evidence actually shows

The best-known study is a one-page paper in the British Medical Journal in 1993 with the title Is Friday the 13th bad for your health? It compared traffic flow and hospital admissions on Friday the 13th with the Friday the 6th before it, and found fewer vehicles on the road but more admissions from road accidents. The authors were careful to say the sample was small and the effect might be behavioural rather than supernatural, and later work has not reliably reproduced it.

Pointing the other way, the Dutch Centre for Insurance Statistics reported in 2008 that Dutch insurers saw fewer accidents, fires and thefts on Friday the 13th than on other Fridays, offering the same explanation from the opposite side: people who believe the date is dangerous behave more carefully, or stay at home.

The honest summary is that the date changes what people do, not what happens to them. That alone is enough to move prices: airlines and hotels have historically seen softer demand on the date, which is why it turns up in lists of cheap days to fly.

Ten years at a glance

One year in seven carries three Friday the 13ths, most carry two, and a year can never carry none — the pattern below is the calendar itself, walked month by month when this page was built.

Read the last column before you plan anything around it: a year with three is not unusual enough to be worth remarking on, and the months they land in shift every year because the count depends on the weekday January 1 falls on and on whether February has 29 days.

The number that quietly goes missing

Once a date is treated as unlucky, the number vanishes from the built environment, and this is where the superstition costs real money.

Buildings. Lift manufacturers have said for decades that a large majority of the tall buildings they equip have no floor labelled 13 — the button goes from 12 to 14, and the storey exists regardless.

Aircraft. Several European carriers omit row 13 from their seat maps, and Lufthansa omits both 13 and 17 — the second because seventeen is the unlucky number in Italy.

Hospitals and hotels. Room 13 is frequently missing for the same reason, on the practical grounds that a room nobody wants is a room that cannot be sold.

None of this changes the calendar. The 13th of the month arrives whether or not the floor above the 12th is called 13, and the finder above will tell you exactly when.

The same arithmetic, other questions

If what you actually want is the weekday of some other date, that is the same arithmetic pointed at a different question — the calendar tools group covers weekday finding, week numbers and leap years. To count the days from now to a date you already know, use days between dates or days from today.

For the other patterns that repeat on their own schedule, see the same calendar year finder, which explains why a year’s Friday the 13ths repeat exactly when its whole calendar does, and the holiday dates group for the rest of the rule-driven dates on this site.