Pi Day is March 14th (3/14), just as Pi is “3.14.” However, many non-U.S. countries represent dates by day-month, making this date 14/3. The date of 3/14 is “American Pi (Day).” Pi is often represented as 22/7 (the fraction), and this would be July 22nd (an International Pi Day).

“Pi Day is each March 14 (3.14), while Pi Approximation Day is July 22 (roughly equal to 22/7” was posted on Twitter by dege13 on March 2, 2009. “We don’t recognise today as PI day. It’s an American PI day because they follow mm/dd/yy. We celebrate it on 22/7 - 22nd July” was posted on Twitter by Swami Gulagulaananda on March 14, 2010. “UK Pi day is 22/7 - which is more accurate than American Pi day, which is just 3.14 ... but not as ammusingly named....” was posted on Twitter by Lucas R Black on March 14, 2010. “22/7 is Pi day 14/3 is American Pi day” was posted on Twitter by Porygon Seizure on March 13, 2020. “International Pi Day is 22/7, which is a better approximation than American Pi Day ” was posted on Twitter by MJW on March 16, 2021.

“Isnt a better choice (approximation ) of Pi day 22/7 than 3/14 ?? Strange ! Thoughts? #PiDay #22JulyforPiDay” was posted on Twitter by Bharath Ananthasubramaniam on March 15, 2018. “I don’t understand why 14/3 is Pi Day. Isn’t 22/7 a better choice?” was posted on Reddit—Dadjokes on March 14, 2022.

Wikipedia: Pi

The number π ( /paɪ/; spelled out as ”*pi*“ ) is a mathematical constant, approximately equal to 3.14159. It is defined in Euclidean geometry[a] as the ratio of a circle’s circumference to its diameter, and also has various equivalent definitions. It appears in many formulas in all areas of mathematics and physics.

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In the United States, Pi Day falls on 14 March (written 3/14 in the US style), and is popular among students.

Twitter

dege13

@dege13

@oliviamunn “Pi Day is each March 14 (3.14), while Pi Approximation Day is July 22 (roughly equal to 22/7). http://tinyurl.com/Pi-day

8:59 AM · Mar 3, 2009·Twitter Web Client

Twitter

Swami Gulagulaananda

@Gulagulaananda

@amoolyatatti We don’t recognise today as PI day. It’s an American PI day because they follow mm/dd/yy. We celebrate it on 22/7 - 22nd July

6:16 AM · Mar 14, 2010·Twitter Web Client

Twitter

Lucas R Black

@LucasBlack

UK Pi day is 22/7 - which is more accurate than American Pi day, which is just 3.14 ... but not as ammusingly named....

5:58 PM · Mar 14, 2010·Echofon

Twitter

Brightly Striped Policy Institute 🥴🥳

@crk5

For those of you who are excited about American Pi day today, just a reminder that the 22nd July (22/7) is officially Pi day in Australia

9:31 PM · Mar 13, 2013·TweetDeck

Twitter

Geoff Dallimore

@PatentUK

It’s not “pi day”, it’s “American pi day”. The rest of the world have to wait until 22/7 for “pi approximation day”.

6:40 PM · Mar 14, 2015·Twitter Web Client

Twitter

Mike Dickison

@adzebill

Hey NZ, yesterday was 3/14 in America: Pi Day. Did you miss it? (Miss American Pi Day?) Don’t worry, we get Approximate Pi Day on 22/7.

2:18 PM · Mar 14, 2016·Twitter for iPhone

Twitter

Bharath Ananthasubramaniam

@bharath_ananth

Isnt a better choice (approximation ) of Pi day 22/7 than 3/14 ?? Strange ! Thoughts? #PiDay #22JulyforPiDay

4:20 AM · Mar 15, 2018·Twitter Web Client

Twitter

Dave Vanness

@djvanness

Replying to @JohnMullahy

I tend to think of 3/14 as American Pi day and 22/7 as European Pi Day.

7:52 AM · Mar 14, 2019·Twitter Web App

Twitter

Porygon Seizure

@porygon_seizure

Replying to @felix_croc

22/7 is Pi day

14/3 is American Pi day

11:23 PM · Mar 13, 2020·Twitter Web Client

Twitter

MJW

@the_lazyknight

Replying to @ThePracticalDev

International Pi Day is 22/7, which is a better approximation than American Pi Day

2:39 PM · Mar 16, 2021·Twitter Web App

Reddit—Dadjokes

Posted by u/coffee-and-chess March 14, 2022

I don’t understand why 14/3 is Pi Day.

Isn’t 22/7 a better choice?

Twitter

‘jokes’ of a guy 😂

@the_alphaman_

I don’t understand why 14/3 is Pi Day.

Isn’t 22/7 a better choice?

#humour

2:00 AM · Mar 15, 2022·Kipruto