History of Pi Day in Timeline

By Popular Timelines Editorial Team · Updated: February 28, 2025

Pi Day is an annual celebration of the mathematical constant π (pi), observed on March 14 due to its first three digits (3.14). Founded in 1988 by Larry Shaw at the Exploratorium in San Francisco, celebrations commonly involve eating pie and pi recitation contests. The U.S. House of Representatives recognized Pi Day in 2009, and in 2019, UNESCO designated it as the International Day of Mathematics.

1988: Pi Day Founded

In 1988, Pi Day was founded by Larry Shaw, an employee of the Exploratorium science museum in San Francisco, marking the start of an annual celebration of the mathematical constant π.

1988: First Large-Scale Pi Day Celebration

In 1988, the earliest known official or large-scale celebration of Pi Day was organized by Larry Shaw at the San Francisco Exploratorium, involving a march around a circular space and the consumption of fruit pies.

March 12, 2009: U.S. House Passes Resolution Recognizing National Pi Day

On March 12, 2009, the U.S. House of Representatives passed a non-binding resolution recognizing March 14, 2009, as National Pi Day.

March 14, 2009: National Pi Day

On March 14, 2009, the U.S. celebrated National Pi Day, recognized by a resolution passed by the House of Representatives.

2009: U.S. House of Representatives Supports Pi Day

In 2009, the United States House of Representatives supported the designation of Pi Day, indicating growing recognition of the day's cultural and educational significance.

2010: Google Doodle Celebrates Pi Day

For Pi Day 2010, Google presented a Google Doodle celebrating the holiday, featuring circles and pi symbols.

2012: MIT Announces "Tau Time"

Starting in 2012, MIT announced they would post application decisions online on Pi Day at exactly 6:28 pm, calling it "Tau Time" to honor both pi and tau.

March 2014: "Pi Month" Observation

During March 2014, some people observed the entire month as "Pi Month," extending the Pi Day celebration.

2015: MIT Decision Release at "Pi Minute"

In 2015, MIT put regular decisions online at 9:26 am, following that year's "pi minute", aligning with digits of Pi.

2015: "Super Pi Day" Celebration

In 2015, March 14 was celebrated as "Super Pi Day" because the date 3/14/15 aligned with the first digits of pi, and the time 9:26:53 represented the first ten digits.

2018: 30th Anniversary Pi Day Google Doodle

For the 30th anniversary in 2018, Google created a Dominique Ansel pie doodle with the circumference divided by its diameter.

November 2019: UNESCO designates Pi Day as International Day of Mathematics

In November 2019, UNESCO's 40th General Conference designated Pi Day as the International Day of Mathematics, formally recognizing its cultural and educational impact.

2020: MIT Decision Release at 1:59 pm

In 2020, MIT released regular decisions at 1:59 pm on Pi Day, representing the first six digits of pi.

August 2024: Asteroid Named After Matt Parker

On 15 August 2024, the main-belt asteroid 314159 Mattparker was named in honor of recreational mathematician Matt Parker, recognizing his popularization of mathematics through 'Pi Day challenges'.