National Pi Day – March 14, 2021

SunMar 14

Pi Day is on March 14, and any day that combines fun, education, and pie is a day worth celebrating! Pi, also known by the Greek letter “π,” is a constant value used in math that represents the ratio of a circumference of a circle to its diameter, which is just about 3.14….15…9265359… (and so on). Not only that, but the fourteenth of March is also Albert Einstein’s birthday, so all together it’s nothing short of a mathematician’s delight.

When is National Pi Day 2021?

The beautiful constant pi (π) is celebrated by mathematicians around the world on National Pi Day on March 14.

History of National Pi Day

To learn about pi, we need to go back a few thousand years and learn about this elusive number. The value of pi was first calculated by Archimedes of Syracuse (287–212 BC), one of the greatest mathematicians of the ancient world.

However, it was first baptized with the Greek letter as its name when William Oughtred called it as such in his works dating back to 1647, later embraced by the scientific community when Leonhard Euler used the symbol in 1737.

But how did Pi Day end up in a country-wide phenomenon? For that, we need to travel to the Exploratorium in 1988 San Francisco, where it was thought up by physicist Larry Shaw.

Shaw linked March 14 with the first digits of pi (3.14) in order to organize a special day to bond the Exploratorium staff together, where he offered fruit pies and tea to everyone starting at 1:59 pm, the following three digits of the value. A few years later, after Larry’s daughter, Sara, remarked that the special date was also the birthday of Albert Einstein, they started celebrating the life of the world-famous scientist.

Pi Day became an annual Exploratorium tradition that still goes on today, and it didn’t take long for the idea to grow exponentially, hitting a peak on March 12, 2009, when the U.S Congress declared it a national holiday.

Now, celebrated by math geeks all around the circumference of the world, Pi Day became a pop culture phenomenon, with several places partaking in the activities, antics, observations and all the pie eating they can.

National Pi Day timeline

March 14, 1988
The Inception

Larry Shaw celebrates Pi Day for the first time.

March 12, 2009
It’s Official

The U.S Congress declared March 14 National Pi Day.

March 14, 2015
Super Pi Day

The first ten digits of pi were achieved on 9:26:53 a.m. (3/14/15/92653)

August 19, 2017
Legacy That Lives

Larry Shaw passes away as Pi Day leaves its mark on pop culture.

National Pi Day - Survey Results

Data according to a top Toronto PR Firm:


3.1415926535 (50%)

Other guesses (50%)

National Pi Day FAQs

Why is pi important?

Pi is very important for calculations in math, engineering, construction, physics and space exploration. Many often consider pi the most important number in all of mathematics.

Which pie should I bake for Pi Day?

Any you’d like. We do not play favorites when pie is concerned. Pies are really simple to make and can be made with several sweet or savory fillings. Apple Pie, Chicken Pot Pie, Pizza pie, be our guest!

Are there any places that give Pi Day deals?

Check restaurants, supermarkets and bakeries over on the Internet for special Pi Day deals. Places like Whole Foods, Boston Market and several pizza chains across the country have special day-long sales.

National Pi Day Activities

  1. Enjoy pie of course

    Pi is a homophone of pie: the 2 words are pronounced similarly, but are spelled differently and mean different things. Celebrate Pi Day by eating lots of pie! Pizza, cherry, apple, you name it!

  2. Throw a potluck party

    Everyone loves to show off their family pie recipe. Make it a potluck and everyone will be inclined to bring their favorite pie to Pi Day, whether it's a pizza pie, a pot pie, a savory pie, or a sweet pie. Make a playlist that features songs like "I Like Pie, I Like Cake" and "American Pie.”

  3. Try making a new pie

    Ever tried to make a pie before? Now's your chance to bake your very own. Not into the sweet stuff? Don't worry, there are various savory pie recipes out there so that everyone can enjoy the warm buttery flakiness that comes with a fresh baked pie.

5 Facts About Pi

  1. People compete in memorizing it

    Rajveer Meena has the record for memorizing the most decimal places of pi at 70,000.

  2. It’s used as stress tests for computers

    Computing pi is a kind of “digital cardiogram” for computers.

  3. A Givenchy men’s cologne is named pi

    So you can smell like pi too if you are the intellectual and visionary kind.

  4. It has other names

    Pi can also be named “Archimedes’ constant,” or “Ludolph’s number.

  5. It has been used by heroes

    Spock foils the evil computer by having it calculate pi’s value in Star Trek’s episode “Wolf in the Fold”

Why We Love National Pi Day

  1. Pi is infinitely cool

    Pi (π) is the ratio of a circle’s circumference to its diameter — and amazingly for all circles of any size, pi will always be the same. Pi is an "irrational number," meaning its exact value is completely unknown. Scientists have calculated billions of digits starting with 3.14159265358979323…, but no recognizable pattern ever emerges. We could continue on and on until infinity and we'd still have no idea what digit might emerge next.

  2. Pi sounds like pie

    If you are a nerd that likes pies this holiday is pretty much the best combination of the most interesting things in life: pie and mathematics. And of course that means that in order to celebrate abstract mathematical items that are somewhat irrational the obvious solution is to incorporate pie into the holiday.

  3. Pi links mathematics to the real world

    Maybe when you were in math class, you stared off into space wondering why on earth 'logs' or 'proofs' mattered so much. Pi is the answer, well at least, one of the things that links math back to real world uses. Because pi is linked to circles it is also linked to cycles, things like calculating waves, ebb and flow, the oceans tides, electromagnetic waves and much more. In addition, many natural world phenomena can also be calculated with pi — like the shape of rivers, the disc of the sun, the spiral of DNA and even the pupil of an eye.

National Pi Day dates

2021March 14Sunday
2022March 14Monday
2023March 14Tuesday
2024March 14Thursday
2025March 14Friday

Let’s get social

Here are some special hashtags for the day.


#NationalPiDay #PiDay #PiDay2021 #MathGeek #MathsIsFun #PiDayTreats #PiDayCelebrations #Mathematics