Just when you thought things couldn’t get any worse: It’s Friday the 13th. For the superstitious among us — or for anybody with paraskevidekatriaphobia, the fear of this unlucky date in particular — that’s really bad news. But here’s the thing: Friday the 13ths are super commonplace. Actually, Friday the 13th is one of the most common dates on the entire calendar.
It’s rare that you won’t have a Friday the 13th mar your yearly schedule. The longest that the Gregorian calendar can ever go between Friday the 13ths is 14 months. That will be the case in 2018, when after a Friday the 13th in July, there won’t be another until September of 2019. This instance occurs whenever a normal year starts on a Tuesday, or when a leap year starts on a Saturday.
The shortest time between Friday the 13ths occurs during normal years that start on a Thursday, like 2015 or 2026. When that happens, February and March have back-to-back Friday the 13ths. The maximum number of Friday the 13ths possible in a single year is three, which happens in February, March, and November whenever a normal year starts on Thursday. This threepeat also happens whenever a leap year starts on a Sunday, like in 2012 (the year the world was supposed to end, according to superstition).
The real bummer for paraskevidekatriaphobics, though, is that Friday that 13th is actually more common than almost all the other possible day and date combinations. The epoch for the Gregorian calendar is 400 years — after that, the whole thing repeats itself. There are 146,097 days in that epoch, and of those days, according to a detailed analysis, there are 28 day and date combinations that appear slightly more often than the others. One of those is Friday the 13th. Not just that, but the 13th is slightly, slightly more likely to fall on a Friday than any other day.
(If you’re wondering, Wednesday the 31st is the least common day and date combo.)
In other words, Friday the 13th is an extremely common date, so the world must just be full of bad luck. Deal with it.
Here are the next 10 Friday the 13ths, just for reference.
