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Friday the 13th Calculator

When is the next Friday the 13th? List the upcoming Friday the 13ths — or Tuesday the 13ths, the unlucky day in Spain and Latin America — with days to go and the count per year.

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How it works

For each month from the start date: weekday of the 13th = (days since 1970-01-01 + 4) mod 7, with 0 = Sunday · keep the months where it is 5 (Friday) or 2 (Tuesday)

The 13th falls on a Friday when the month begins on a Sunday, so every calendar year has at least one and at most three Friday the 13ths (the same holds for Tuesday the 13th, when the month begins on a Thursday). Over the 400-year Gregorian cycle the 13th lands on a Friday 688 times out of 4,800 months — slightly more often than any other weekday. In Spain, Greece and much of Latin America the unlucky day is Tuesday the 13th (“martes 13”) rather than Friday.

Worked example

Searching from October 5, 2026: the next Friday the 13th is Friday, November 13, 2026, 39 days away. 2026 has three of them (February, March and November) and 2027 has one (August 13, 2027).

Sources: Friday the 13th (Wikipedia) · Time and Date — Friday the 13th

Frequently asked questions

How many Friday the 13ths are there in a year?

Always between one and three. 2026 has three (February, March and November); 2027 has just one, in August.

Why does Friday the 13th always come in a month that starts on Sunday?

Day 1 and day 13 are 12 days apart, which is 5 weekdays later modulo 7 — so if the 1st is a Sunday, the 13th is a Friday.

Why is Tuesday the 13th unlucky in Spanish-speaking countries?

Tuesday (martes) is named after Mars, the god of war, and tradition links it to the fall of Constantinople on a Tuesday in 1453. Hence the saying “en martes, ni te cases ni te embarques”.

Is the 13th really more likely to be a Friday?

Yes, very slightly. In the 400-year Gregorian cycle the 13th falls on a Friday 688 times, more than on any other weekday (684–687 for the rest).

What is the fear of Friday the 13th called?

Paraskevidekatriaphobia (or friggatriskaidekaphobia). Fear of the number 13 alone is triskaidekaphobia.

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This calculator is for educational purposes. Double-check important results before acting on them.