When Is Pi Day 2025 Date. Pi day march 14, friday © shutterstock pi day is an unofficial holiday celebrated around the world on march 14th to honor the mathematical constant π (pi). Unlike some holidays, pi day remains fixed on this date annually, offering enthusiasts a consistent opportunity to indulge in all things mathematical.

Pi day is next on friday, march 14, 2025 always know when is pi day. Well, that’s because if you round pi to two decimal places, you get 3.14.