November 13, 2026 is the third Friday the 13th of the year, after February 13 and March 13. That won’t happen again until 2037. The next one after November comes on August 13, 2027, and then the calendar produces the longest possible drought: 14 months with no Friday the 13th at all, until October 13, 2028.

None of this is random. Friday the 13th follows fixed rules set by the structure of the Gregorian calendar, and over the full 400-year cycle of that calendar, the 13th of the month lands on a Friday more often than on any other day of the week.

One rule decides every Friday the 13th

The 13th of a month is a Friday exactly when the 1st of that month is a Sunday. Twelve days separate the 1st from the 13th, which is one full week plus five days, and five days after Sunday is Friday. So the question “which months have a Friday the 13th?” is really “which months start on a Sunday?”

That, in turn, depends on only two facts about the year: the weekday of January 1 and whether the year is a leap year. Each month begins a fixed number of weekdays after January 1, because each month has a fixed length. January’s 31 days push February’s start three weekdays later; February’s 28 days (four exact weeks) leave March starting on the same weekday as February, and so on.

Two consequences follow. First, every shift from 0 to 6 appears at least once in both rows, so some month always starts on a Sunday: every year has at least one Friday the 13th. Second, no shift appears more than three times, so no year can have more than three. In a common year, February, March and November share the shift 3, which is why a common year starting on a Thursday, like 2026, gets its three Friday the 13ths in exactly those months. In a leap year, January, April and July share the shift 0, so a leap year starting on a Sunday gets three in those months, as 2012 did and 2040 will.

All 14 possible years

Because only the starting weekday and leap status matter, there are just 14 kinds of calendar year. Every year of the Gregorian calendar is one of them.

Six of the 14 year types have just one Friday the 13th, six have two, and two have three. The leap day matters because it shifts every month from March onward by one extra weekday, which is why the same starting weekday produces a different set of months in a leap year.

Friday the 13th dates from 2025 to 2030

The gaps between them range from 4 weeks to 14 months. The shortest possible gap is exactly 28 days, from February 13 to March 13 in a common year, since February’s 28 days are four whole weeks; 2026 had one. The longest possible gap is 14 months, and the next one runs from August 13, 2027 to October 13, 2028. The previous 14-month gap ran from July 13, 2001 to September 13, 2002. After October 2028, the wait is short: April 13, 2029 is only six months later.

Why the 13th lands on Friday more than any other day

Over a long enough stretch, you might expect the 13th to fall on each weekday one-seventh of the time. It almost does. The Gregorian calendar repeats exactly every 400 years, because 400 years contain 146,097 days (365 × 400 plus 97 leap days), and 146,097 divides evenly by 7 into 20,871 weeks. So every date falls on the same weekday it did 400 years earlier, and the pattern of 13ths can be counted completely.

Those 400 years contain 4,800 months, and 4,800 is not divisible by 7, so the 13ths cannot split evenly among the weekdays. The count, first worked out as a puzzle in the American Mathematical Monthly in 1933 (B. H. Brown’s solution to Problem E36), comes out like this:

Over the Gregorian calendar’s 400-year cycle, the 13th falls on a Friday 688 times, more than on any other weekday. The edge exists only because the calendar skips three leap days every four centuries. worldtimedata

The margin is tiny: Friday beats the least common weekdays by just 4 occurrences in 400 years, and its share of 14.33% compares with an even 14.29%. It works out to an average of 1.72 Friday the 13ths per year.

The imbalance comes entirely from the Gregorian century rule. Under the older Julian calendar, where every fourth year is a leap year without exception, the calendar repeats every 28 years, and those 28 years contain 336 months, which divides evenly by 7. Counting the same way, the 13th lands on each weekday exactly 48 times per Julian cycle, with no favorite; that figure is our own calculation from the calendar rules. The Gregorian reform, which drops the leap day in three of every four century years (1700, 1800 and 1900 were not leap years; 2000 was), breaks that symmetry. Which weekday ends up on top is a matter of bookkeeping rather than a deeper pattern, and in the Gregorian arrangement, Friday wins. The reasons the two calendars diverge are covered in Julian vs Gregorian.

The superstition is younger than it looks

Suspicion of the number 13 and of Fridays each goes back centuries in European folklore, but the combination of the two into a single unlucky date is surprisingly recent. One early documented reference in English appears in H. S. Edwards’ biography of the composer Gioachino Rossini, who died on Friday, November 13, 1868; Edwards noted that Rossini considered both Fridays and the number 13 unlucky. The idea spread widely in the early 20th century, helped by Thomas W. Lawson’s 1907 novel Friday, the Thirteenth, in which a broker exploits the superstition to set off a panic on Wall Street.

The often-repeated link to the arrest of the Knights Templar on Friday, October 13, 1307 may not have been connected to the superstition until the 20th century. It was popularized by fiction, including Maurice Druon’s 1955 novel The Iron King and Dan Brown’s 2003 The Da Vinci Code, rather than by medieval sources. The fear even has clinical-sounding names: paraskevidekatriaphobia, from the Greek words for Friday and thirteen, and friggatriskaidekaphobia, after Frigg, the Norse goddess behind the name of Friday.

Other cultures fear different dates

The unlucky date isn’t universal. In Spanish-speaking countries, the day to worry about is Tuesday the 13th, martes trece. Greek tradition also treats Tuesday as unlucky, and the fall of Constantinople to the Fourth Crusade on Tuesday, April 13, 1204 is often cited in that context. A Tuesday the 13th happens in any month that starts on a Thursday, and 2027 has two: April 13 and July 13.

In Italy, the unlucky date is Friday the 17th rather than the 13th. That happens in any month that starts on a Wednesday, and in 2027 it falls on September 17 and December 17. The calendar math is identical; only the date people choose to fear is different.