It isn't The Pioneer Woman without "pi!" In the baking sense, Ree Drummond is no stranger to the pastry, whether she's whipping up apple pie, pot pie, or Ladd's favorite chocolate pie. One of the best days to eat pie? In the middle of March, when Pi Day lands on the calendar! But wait: What exactly is Pi Day? And what does it have to do with our favorite dessert?
If those questions are running through your head, keep on reading! Ahead, you'll find everything you need to know about Pi Day. (And, unlike many other mathematical concepts, it's easy as pie to understand!) In short, Pi is one of the most important numbers to ever exist. You've probably seen it rounded down to its commonly used approximation, 3.14. But those three digits are just a small piece of the pie—pun intended—and there's so much more about the number that makes it worthy of having its own special day!
So before you order that new pie pan, read on to find out more about Pi Day, including a brief history of the March holiday, when it falls in 2025, and how to celebrate it. (Here's a hint: you can bake a pie recipe or even make a pizza pie!)
What is Pi?
Going back to the holiday's roots, the mathematical symbol Pi is the ratio of the circumference of a circle to its diameter. The value of Pi is approximately 3.14, but it has infinite decimal places and expands to 3.14159265 (and beyond)!
Pi is often used to answer questions about circular or spherical things, like a cookie, pie, or planets in the sky—which is why it's commonly used in space exploration! Although we now easily recognize the Greek letter π (Pi), it wasn't associated with the mathematical concept until 1706, when philologist William Jones began using the symbol.
What is Pi Day?
Now that you have a better understanding of what Pi is, it's time to learn what Pi Day is! The first unofficial Pi Day was initiated in 1988 by physicist Larry Shaw at the San Francisco Exploratorium, who wanted to celebrate the famous number on its corresponding day. From that day until his passing in 2017, Larry led annual Pi Day celebrations at the museum, complete with fruit pies and tea! While Pi Day was only officially instated as a national holiday in 2009, the mathematical symbol, Pi, has been around for 4,000 years.
When is Pi Day in 2025?
If you couldn't already tell by the number this mathematical symbol represents, Pi Day is celebrated on Friday, March 14, 2025. That's because the date is written as 3/14 (at least in the United States). If you want to get even more technical about it, the exact time to celebrate Pi Day would be 1:59 a.m. or p.m., as the first six digits of Pi are 3.14159. Coincidentally, March 14 is also the date of mathematician Albert Einstein's birthday!
How do you celebrate Pi Day?
Once Larry Shaw initiated the first Pi Day celebration in 1988, the quirky celebration of math and baked goods began to spread throughout America, especially in the science, math, and teaching communities. March 14 became the perfect day for math teachers to capture students' attention with promises of pie so they could teach them about Pi! So, if you're a student or work in space exploration, your Pi Day probably consists of solving math equations with Pi while eating a slice of pie.
Even if you're not in a math-adjacent field, people of all backgrounds celebrate this light-hearted holiday by making or eating pie, including those of the sweet, savory, and pizza varieties. Due to the popularity of the holiday, many businesses now offer Pi Day deals, such as whole pizzas or pies, for only $3.14!
Nitya Rao is the editorial assistant at The Pioneer Woman, covering stories ranging from food, fashion, beauty, lifestyle, news, and more.
