What Pi Day is

Kept on 14 March for the American month/day rendering of 3.14. It began at San Franciscou2019s Exploratorium in 1988 and became a US House-recognised observance in 2009; UNESCO designated it the International Day of Mathematics in 2019.

It is a mathematics-outreach occasion rather than a holiday. Countries writing dates day-first sometimes mark 22 July instead, for the approximation 22/7.

Why this date does not move

The countdown at the top of this page is live, and the date beneath it is the next occurrence. This is a fixed date: it falls on the same day of the month every year, so only the weekday changes.

The date follows a fixed calendar rule, so it can be computed years ahead. Where a country observes this as a public holiday, the official government calendar remains the authority for whether the day off is moved when it falls on a weekend.

What is coming up next

Once this date passes, the countdown moves on according to the recurrence rule described above. Calculated lunar dates remain estimates until the relevant calendar or local authority confirms them. See the full list of upcoming events, or use the countdown timer for a duration of your own.