Pi Approximation Day 2024. 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. Celebrate pi approximation day on july 22 with a slice of your favorite pie!

Pi approximation day 2023 will be observed on saturday, july 22, 2023. This special day was first celebrated in 1949 to commemorate the achievement of archimedes, who approximated pi—the ratio between the circumference and.