when is pi day

Pi Day is celebrated every year on March 14, because the date 3/14 matches the first three digits of pi (3.14).

Quick Scoop

Pi Day is an annual celebration of the mathematical constant π (pi), the ratio of a circle’s circumference to its diameter.

It’s become a fun mix of math culture and food culture, since “pi” sounds like “pie” and pies are circles.

Why March 14?

• Written as 3/14, March 14 lines up with the first three significant digits of pi: 3.14.

• Many celebrations also highlight the time 1:59 (making 3/14 1:59 → 3.14159).

• It also coincides with Albert Einstein’s birthday, which adds extra nerdy charm to the date.

How people celebrate

• Eating pie (sweet or pizza) as a playful nod to “pi/pie” and the circle theme.

• Pi memorization contests, trying to recite as many digits of π as possible.

• School activities, math games, and “Pi Day” events organized by teachers and science museums.

• Special deals from pie and pizza places on March 14.

A tiny bit of history

• Pi Day was first formally celebrated in 1988 at the Exploratorium science museum in San Francisco, led by physicist Larry Shaw.

• In 2009, the U.S. House of Representatives officially recognized March 14 as National Pi Day.

• In 2019, UNESCO designated March 14 as the International Day of Mathematics.

Related “pi” dates fans mention

• Pi Approximation Day on July 22 (22/7, a common fractional approximation of π).

• June 28 (6/28) sometimes celebrated as “Tau Day,” since 2π ≈ 6.28.

TL;DR: Pi Day is on March 14 (3/14) every year, chosen because it matches the first digits of π, and it’s now a global mini‑holiday for math, circles, and lots of pie.

Information gathered from public forums or data available on the internet and portrayed here.