What to know
- Jeffrey Rosenthal, a University of Toronto statistics professor, found no evidence that Friday the 13th is unluckier than any other day, after studying explained deaths in Ontario.
- Three common origin stories behind the superstition are rooted in Christianity’s Last Supper, the Knights Templar in France, and a Norse legend involving Loki.
- The number 13 may also be considered unlucky because it is less familiar than 12, which appears frequently in everyday life, from clocks to calendars and egg cartons.
- Rosenthal says the superstition is reinforced by confirmation bias, where people are more likely to blame bad experiences on Friday the 13th.
Scared of stepping on a crack in the sidewalk or walking under a ladder? Or maybe you’re terrified of seeing a black cat or raven in the wild.
Or perhaps you’re too afraid to leave the house at all in case something bad happens once you step out into the unknown.
These are just a few examples of popular superstitions that plague the infamous date, Friday the 13th. In 2026, three Fridays have fallen on the 13th: Feb. 13, Mar. 13, and Nov. 13.
But is this notoriously feared day actually any unluckier than any other day in the year? Jeffrey Rosenthal, a statistics professor at the University of Toronto, says no.
He authored a study earlier this year titled, Friday the 13th, Full Moons, and Holiday Blues: Ontario Death Date Distributions, which looked at the statistical probability of unexplained deaths in Ontario, and found no correlation between unexpected deaths and Friday the 13th.
Rosenthal examined over 250,000 unexplained deaths, which included everything from homicides to motor vehicle accidents, to sudden heart attacks.
“I thought, if Friday the 13th is really unlucky, then there should be more of these things happening on Friday the 13th than on other days,” he explains.
“That was the way we could scientifically test this prediction. And as I suspected, we did not find any significant change. The rates of these unfortunate and sudden deaths happening were virtually the same on all different days.”
Where did ‘Friday the 13th’ come from?
Rosenthal says there are quite a few explanations for why Friday the 13th has gained the reputation as the unluckiest day, but three common ones are rooted in religion and mythology.
He says one origin comes from Christianity and The Last Supper’s 13 guests — which featured Jesus alongside his 12 apostles.
“Then when Jesus died, it was on a Friday. So right away, you’ve got that Friday and the 13th in there for something bad.”
The second origin story dates back to the early 14th century in France, where King Philip IV rained down on the Knights Templar,a Catholic military order, with a brutal crackdown, which took place on Friday, Oct. 13, in 1307.
Finally, Rosenthal recalls a Norse legend about Loki (not the Marvel Loki), who was the 13th guest at a dinner party in memory of Baldur the Beautiful, who he had killed.
But another more common reason people associate the number 13 with bad luck is that it’s less commonly seen in the wild. For example, clocks count to 12, eggs come in 12, and there are 12 months in a year.
“The numbers one to 12 are all right there, but then 13, we don’t see as often. So maybe it’s a bit unfamiliar and mysterious.”
Confirmation bias can be the culprit
Rosenthal says once someone believes Friday the 13th is unlucky, then they’re going to associate anything bad which happens to the day. He says this is a prime example of confirmation bias.
“Say something that happens to you on a Friday the 13th, even something that’s not such a big deal, you’ll say, ‘It’s happening because it’s Friday the 13th,’” he says.
“Then if on another day, that same thing happens, you might not like it, but you won’t associate it with any superstition.”
