Pi Day

Pi Day History

Pi Day celebrates the mathematical constant π (pi), 3.141592653... Pi is the ratio of a circle's circumference to its diameter. The circumference of a circle is defined as its arc length while the diameter is defined as the longest chord of the circle. Pi is a special number due to its infinite and pattern-less nature. This means that the digits after the decimal point never repeat themselves in a specific pattern.

Pi Day was established in 1988 by Physicist Larry Shaw. Shaw was an employee at the San Francisco Exploratorium where the first Pi Day was held. It took place on March 14th (3/14), given that the first digits of Pi are 3.14. On March 12, 2009, the U.S House of Representatives recognized March 14 as National Pi Day.

Top 8 Facts for Pi Day in 2026

• For the upcoming observance of Pi Day, the global community will focus on the newly designated theme Mathematics and Hope, which was established by UNESCO and the International Mathematical Union to highlight how mathematical reasoning can inspire solutions for a sustainable and equitable future.
• A monumental milestone in computational history was achieved just months prior to this celebration when researchers at StorageReview calculated the constant to a record-breaking 314 trillion digits, specifically reaching the sequence 314,159,265,358,979 to mirror the value of pi itself.
• The date holds profound historical significance as the birthday of the legendary theoretical physicist Albert Einstein and the anniversary of the passing of cosmologist Stephen Hawking, creating a day of dual remembrance for two of the most influential minds in science.
• The Jet Propulsion Laboratory continues its decade-long tradition of the NASA Pi Day Challenge, where students and enthusiasts solve real-world problems such as calculating the orbital eccentricity of asteroids or determining the landing drag for parachutes on Mars.
• Beyond the classroom, the constant continues to permeate creative culture through works like the psychological thriller Pi directed by Darren Aronofsky and the melodic track Pi by Kate Bush, which features the artist singing the first 22 decimal places of the number.
• Enthusiasts of the Chudnovsky algorithm often engage in linguistic challenges by writing in Pi-lish, a constrained style of prose where the number of letters in each word must correspond to the consecutive digits of pi.
• Science centers around the country, such as The Franklin Institute, are marking the occasion with specialized programming like the planetarium show Pi in the Sky, which explores the geometry of the curved universe and the physics of celestial orbits.
• Some participants observe a literary variation of the holiday by composing a pi-ku, a three-line poem that follows a syllable structure of three, one, and four to honor the first three digits of the constant.

In the News and Trending in the US for Pi Day

Top things to do in the US for Pi Day

• Memorize as many digits of Pi as you can (remember, the World Record Holder was able to memorize 70,000 decimal places of pi).
• Eat a pie to celebrate Pi day and earn bonus points if your can calculate Pi for your pie's circumference! Here are some twists on traditional pies that you can try:
  1) Avocado and cream cheese pie
  2) Cheeseburger and pickle pie made from ground beef, cheese, and chopped dill pickles
  3) Mac and Cheese Pie topped with bacon
  4) Hot dog pie covered with a layer of cheese
  5) Twinkie pie topped with whipped cream
• Practice your geometry and algebra equations that contain the constant Pi. Here are some useful formulas to help you:
  Circumference of a circle = 2 πr
  Area of a Circle = π r^2
  Volume of a Cylinder = π r^2h
  where r=radius and h=height
• Go for a 3.14km walk to celebrate Pi Day.
• Watch movies about mathematics:
  1) Good Will Hunting (1997)
  2) A Beautiful Mind (2001)
  3) The Number 23 (2007)
  4) Rain Man (1988)
  5) The Theory of Everything (2014)