Pi Approximation Day 2025 Date. Since 22/7 is a fraction historically valued for its closeness to pi—at five decimal places it is 3.14285—july 22 is recognized by math enthusiasts as pi approximation day. The pi approximation day is celebrated on july 22 as the date 22/7 marks the approximate value of pi (22.7).
Pi approximation day is celebrated on july 22 every year. Pi approximation day is observed on july 22 (22/7 in the day/month date format), since the fraction 22 ⁄ 7 is a common approximation of π, which is accurate to two decimal places and dates.