National Pi Day 2025. What should we do on national pi day? The beautiful constant pi (π) is celebrated by mathematicians around the world on national pi day on march 14.

Pi is an important symbol in mathematics, statistics and physics. The first 6 digits of pi (π) are 3.14159, which means a good time to celebrate on march 14 (3/14) at 1:59 (am/pm).