Friday the 13th: Origins of why the day is considered unlucky

August 13 marks the one and only Friday the 13th of 2021. The last occurred in November of 2020, and the next won’t come until May of 2022.

The day has long evoked a range of emotions for those who are superstitious. Similar to walking under a ladder or breaking a mirror, many believe that Friday the 13th brings bad luck — to the point of inspiring a horror movie franchise and even a late 19th-century secret society. 

Why is Friday the 13th considered unlucky?

It remains unclear when negative superstitions began swirling around Friday the 13th. But while the number 12 has generally been associated with completeness — 12 months of the year, 12 days of Christmas, 12 zodiac signs — the number 13, specifically, has long been associated with bad luck.

The ancient Code of Hammurabi, one of the earliest and most complete written legal codes, reportedly omitted a 13th law from its list of legal rules, according to History.com. Though this was likely a clerical error, superstitious people sometimes point to this as proof of the number’s negative associations.

In Western lore, experts believe the fear over 13 started in the Bible. Thirteen guests attended the Last Supper, including Jesus and his 12 apostles — one of whom, Judas, betrayed him. The next day was Good Friday, the day of Jesus’ crucifixion. The Last Supper seating arrangement is believed to have created a Christian superstition that having 13 guests at a table was a bad omen, according to the site.

FILE - The number 13 is shown on a park bench in a file image taken on March 1, 2018, in Gera, Germany. (Photo by Stephan Schulz/picture alliance via Getty Images)

Regarding the day of Friday, the negative connotation may also have roots in Christianity, History.com explains. Jesus was crucified on a Friday. Some believe Friday was the day Eve gave Adam the forbidden fruit from the Tree of Knowledge and the day that Cain killed his brother, Abel.

Fear of Friday the 13th

Some who fear Friday the 13th suffer from friggatriskaidekaphobia — described as having a "morbid, intense, excessive and irrational fear" of the day, according to allaboutcounseling.com, a site providing information on counseling and social issues.

The Stress Management Center and Phobia Institute estimates that between 17 to 21 million Americans suffer from this phobia.

The exclusive Thirteen Club

In the late-19th century, a New Yorker named Captain William Fowler sought to remove the stigma surrounding the number 13 by founding an exclusive society called the Thirteen Club, according to the History Channel.

The group dined on the 13th day of the month in room 13 of the Knickerbocker Cottage, which he owned and later sold on Friday, April 13, 1883. According to History.com, several former U.S. presidents — Chester A. Arthur, Grover Cleveland, Benjamin Harrison and Theodore Roosevelt — were members at one point or another.

Skipping the number 13

Many people also suffer from triskaidekaphobia, defined as the irrational fear of the number 13. Airlines such as Air France often don’t have a 13th row, and many buildings in the U.S. don’t have a 13th floor.

Experts say that it’s an economic decision — as customers would not spend money on something they thought was cursed.

The number 13 around the world

In Asia, 13 is just another number. And in China, it’s the number 4 that provokes the most fear. The phenomenon, known technically as "tetraphobia," exists because of linguistic reasons.

"In Chinese, the number 4 sounds much like the word for ‘death,’" Patrick Alexander, a social anthropology lecturer at Oxford University, told the Associated Press. "As a result, the number 4 is often omitted in elevators and other public contexts."

The number 8 is particularly lucky in China and Japan because it sounds similar to "prosperity" or "wealth."

In Greece, Mexico and Spain, Tuesday the 13th is thought to be cursed.

The Associated Press contributed to this story. It was reported from Cincinnati.

Editor’s note: A version of this article was originally published on Nov. 13, 2020.