World Pi Day: What It Is and When It Was Established

Today, Friday (March 14, 2025), is World Pi Day, and many are wondering when it was established and the significance of this celebration. World Pi Day is an annual celebration of the mathematical constant π, which represents the ratio of a circle’s circumference to its diameter. The day is celebrated every year on March 14. Notably, in the American date format, the month precedes the day (3/14), aligning with the first three digits of pi (π = 3.14159…). Besides Pi Day, there’s also Pi Approximation Day on July 22 (22/7 in our date format), as the fraction 22/7 is a common approximation of pi, dating back to Archimedes. The first significant celebration of Pi Day was organized in 1988 by American physicist and artist Larry Shaw at the Exploratorium museum in San Francisco. The event included a procession around one of the museum’s circular spaces and eating round fruit pies (the word ‘pie’ sounds like ‘pi’ in English). The Exploratorium continues to host Pi Day celebrations. In the 1990s, the European association ‘Friends of the Number Pi’ (Freunde der Zahl Pi) played a significant role since its establishment in Vienna in 1995. On March 12, 2009, the U.S. House of Representatives passed a non-binding resolution recognizing March 14, 2009, as National Pi Day. For Pi Day in 2010, Google unveiled a festive Google Doodle featuring circles and pi symbols. This tradition has continued in other years, such as the 30th anniversary in 2018. The entire month of March 2014 (3/14) was celebrated by some as ‘Pi Month.’ In 2015, Pi Day held special significance, especially at 9:26:53 p.m., when the date (3.14.15) and time represented the first ten digits of pi. In 2016, Pi Day was notable because the date (3/14/16) represented pi rounded to four decimal places. Lastly, it’s worth noting that exactly 146 years ago today, Albert Einstein, the ‘father’ of the theory of relativity, was born.