Pi Day
Celebrate the most famous number in mathematics on 3/14.
About
Pi Day is an annual celebration of the mathematical constant π (pi), observed on March 14 because the date, written as 3/14 in the US format, represents the first three digits of pi (3.14). The day is marked by math enthusiasts, educators, and students with pi-themed activities, pie eating, and learning about the constant's role in geometry and physics.
History
Physicist Larry Shaw organized the first large-scale Pi Day celebration at the San Francisco Exploratorium in 1988. In 2009 the US House of Representatives passed a non-binding resolution recognising March 14 as National Pi Day. In 2019 UNESCO declared it the International Day of Mathematics, broadening the celebration globally.
Where It's Observed
Cultural Context
US United States
Pi Day was born in the US and remains a beloved school holiday. American math teachers hold pi-memorisation contests, schools serve actual pies, and science museums run special programming. Congress's 2009 resolution made it a rare case of mathematical recognition in US law.
KR South Korea
South Korea's STEM-focused education culture embraces Pi Day through school math competitions and science festivals. The date aligns with Korea's national push to strengthen science and engineering education, and Korean students often challenge each other to memorise pi to hundreds of digits.
JP Japan
Japanese math culture's love of precision gives Pi Day natural resonance. University clubs hold calculation contests, and the connection between March 14 and White Day (when men return Valentine's gifts) sometimes leads to creative pi-themed sweets being exchanged.
How to Participate
- 01Recite digits of pi — how far can you go?
- 02Bake or eat a pie (any kind!)
- 03Solve geometry problems or explore math puzzles
- 04Teach children why circles matter in daily life
Frequently asked questions
When is Pi Day?+
Pi Day is observed annually on March 14. The date is fixed each year — March 14 — and does not shift based on the lunar calendar or weekday.
What is Pi Day?+
Pi Day is an annual celebration of the mathematical constant π (pi), observed on March 14 because the date, written as 3/14 in the US format, represents the first three digits of pi (3.14). The day is marked by math enthusiasts, educators, and students with pi-themed activities, pie eating, and lear…
Is Pi Day a public holiday?+
Pi Day is an international observance or awareness day, not a public holiday in most countries. It does not typically result in days off work or school closures, though some countries and organisations hold official events.
How can I participate in Pi Day?+
Recite digits of pi — how far can you go? Bake or eat a pie (any kind!) Solve geometry problems or explore math puzzles These are some of the most accessible ways to engage with the day's purpose.
Which countries observe Pi Day?+
United States, Global — mathematics communities worldwide.
Mark the date
Download a free printable calendar for 2027 and never miss Pi Day.