13 Things About Friday the 13th

Is this cat unlucky?Happy Friday the 13th, everyone!

Growing up, I always knew that Friday the 13th was an unlucky day. I don’t know where I heard it first, but I’ve known that for as long as I can remember. It’s a belief that seems to be ubiquitous, at least in North American culture, although one that’s not taken too seriously by most people. It ranks right up alongside “don’t walk under ladders” and “don’t let a black cat cross your path” as one of the most widespread superstitions in our culture.

To celebrate Friday the 13th, I’ve decided to put together a list of 13 things that you may or may not want to know about Friday the 13th.

  1. Like all things, there is a phobia of Friday the 13th called friggatriskaidekaphobia, or paraskevidekatriaphobia. [1]
  2. Though there are many historical references to Friday the 13th (and Fridays, in general) being an unlucky day, nobody’s quite sure of the origin of this superstition. Spooooky. [2]
  3. There are no shortage of theories concerning why the number of 13 is considered unlucky. Some theories include: the 13 attendees of Jesus’ last supper, the 13 months occasionally required in lunisolar calendars required to synchronize lunar and solar cycles, and Loki of Norse Mythology fame crashing Odin’s party (to which he invited 11 friends; 11 + 1 = 12). [3][4]
  4. The Canadian television series, Friday the 13th: The Series, was filmed in Toronto, Canada. Yet despite all of those strikes against it, the show still ran for three seasons.
  5. Fact: Friday the 13th is not particularly unlucky for animals. There is no statistically significant increase in the caseload of urban small animal emergency clinics on Friday the 13th, according to this study.
  6. Friday the 13th isn’t unlucky for women, either. It turns out that if you’re a female driver, Friday the 13th isn’t a particularly unlucky day for you to get behind the wheel of your car. Or maybe it is! (Click here for accompanying sound effect.)
  7. You don’t have to worry about undergoing a tonsillectomy on Friday the 13th, because post-tonsillectomy hemorrhages are not more frequent on Friday the 13th. (Also a relief if you’re a redhead.)
  8. According to snopes.com, “the claim that the Friday the 13th superstition began with the arrest of the final Grand Master of the Knights Templar, Jacques Demolay, on Friday, October 13, 1307, is a modern-day invention”. [5][6]
  9. If you live in the UK, you might want to consider staying home on Friday the 13th, because your risk of getting into a traffic accident could increase by as much as 52%.
  10. On Friday the 13th, somewhere between $800 and $900 million (USD; as of 2004) is lost due to people not flying or conducting business as they usually would, according to Donald Dossey, founder of the Stress Management Center and Phobia Institute in Asheville, North Carolina. (Though I’m somewhat skeptical of this claim. I’d like to see how he came up with those numbers.) [7]
  11. On Friday, April 13, 2068, there is a 0.000250000% (or 1 in 400,000) chance the asteroid 99942 Apophis will collide with the Earth [8].
  12. And if you’re brave enough to venture outdoors today, if you live in or near Port Dover, Ontario, you can go see a sweet motorbike rally.

And just to play it safe, I’m going to end the list there. Feel free to add your own #13 in the comments, though… IF YOU DARE!

Thanks to Scott GavuraErik Davis, and Jonathan Abrams for their help with researching these points.

4 Responses to “13 Things About Friday the 13th”

  1. Nice write-up Mitchell.

    We covered #9 on The Reality Check in episode #30. IIRC, we debunked #9. The newer studies that debunked the older one is linked to in the show notes.

  2. 13. The Nonergodic property of Friday 13th: “A surprising property of our calendar is that not all days of the week have equal chance of being the 13th of the month if you consider the long-run. For example, if you randomly select the 13th day of any month from all years between say 2,000 AD and 1,000,000,000,000 AD then the probability that it is Friday is exactly 43/300 which is slightly larger than 1/7. Moreover, in the long-run, the 13-th of the month has a higher probability of falling on a Friday than any other weekday.”


  3. 13. Celebrate Friday the 13th by throwing a Friday the 13th party! http://www.wikihow.com/Celebrate-Friday-the-13th

  4. Teshi says:

    Today is International Left Hander’s Day. A sinister coincidence?



  • Mitchell Gerskup

    Mitchell Gerskup recently graduated from the University of Toronto with a degree in Economics and Philosophy. An avid atheist and skeptic, he has served as the President of the University of Toronto Secular Alliance, helping to promote science, reason and critical thinking around Toronto. He also volunteers with the Centre for Inquiry’s Ontario branch, and currently sits on the CFI’s Committee for the Advancement of Scientific Skepticism. Mitchell is also an accomplished competitive debater, having debated all across Canada. In addition to issues of economics and philosophy, Mitchell is interested in the fields of science and technology.