Pi Day
Pi Day is the worldwide celebration of the number π, held every year on March 14 because the date matches the first three digits of pi: 3.14. It's the nerdiest, pie-eatingest holiday on the calendar.
A quick history of Pi Day
Pi Day was invented in 1988 by physicist Larry Shaw at the Exploratorium in San Francisco. The first celebration involved a circular march around one of the museum's monuments followed by — what else — eating fruit pies. In 2009, the US House of Representatives formally recognized March 14 as National Pi Day. In 2019, UNESCO declared it the International Day of Mathematics, bringing schools and universities around the world into the fun.
Pi Minute and Pi Second
For extra precision, fans celebrate Pi Minute at 1:59 on March 14 (3.14159…), and the once-a-century Pi Second at 1:59:26 (3.1415926…). The ultra-rare "Pi Day of the Century" fell on 3/14/15 at 9:26:53 — eleven digits of pi matching the exact date and time, something that won't happen again until 3/14/2115.
How to celebrate Pi Day
- Eat pie. Literally any pie. Circular pie is traditional because of the obvious pun.
- Memorize digits. Start with ten and see how far you get. Pi — The Game makes it fast and fun.
- Host a recitation contest. Everyone takes turns reciting pi until they blunder. Last digit standing wins.
- Solve a pi-flavored puzzle. Try our pi quiz or Pi Day trivia.
- Make art. Print our Pi Day coloring sheets.
- Read a piem. A poem where the length of each word encodes a digit of pi. See our piems collection.
Classroom activities
- Measure real circles. Have students measure the circumference and diameter of household objects with string and compute C/d. The answers should all hover around π — a magical moment when the math becomes real.
- Buffon's needle experiment. Drop toothpicks on a lined page and count crossings to estimate π empirically.
- Digit relay race. Teams race to write out the first 50 digits correctly.
- Pi coloring & art. Assign each digit 0–9 a color, then color a spiral or grid by digit sequence.
Pi Day food ideas
- Apple, pecan, or key lime pie (classic).
- Pizza pie (savory).
- Pi-shaped cookies (serious bakers only).
- Round fruit platters (healthy option, still on brand).
- Anything you can cut into slices subtending measurable central angles.