Pi Day2026 · Date · History · Messages
The U.S. House of Representatives agreed to a resolution supporting the designation of Pi Day and encouraging schools and educators to observe it with mathematics activities
About Pi Day
Pi Day is observed on March 14, a date written 3/14 in month/day format and therefore associated with the familiar approximation 3.14 for the mathematical constant pi.
The Exploratorium traces the celebration to staff member Larry Shaw, who created Pi Day there in 1988. The observance later spread widely through schools, museums and mathematics communities.
Why Pi Day matters
Pi Day turns a mathematical idea into an accessible public-engagement occasion, using demonstrations, puzzles, circles, measurement and playful activities to make mathematics more visible.
It is an educational and cultural observance rather than a U.S. federal public holiday. Congressional action in 2009 supported the designation and encouraged educational activities.
History of Pi Day
Exploratorium history credits staff member Larry Shaw with creating Pi Day in 1988. A preserved interview with Shaw and colleagues identifies March 14, 1988 as the first Pi Day celebration.
On March 12, 2009, the U.S. House of Representatives passed H.Res. 224, supporting the designation of Pi Day and encouraging schools and educators to use the occasion for mathematics and science activities.
The resolution itself explains the March 14 connection: pi can be approximated as 3.14, making 3/14 a natural calendar shorthand for the constant.
How the observance developed
This timeline uses documented milestones from reviewed sources. Missing stages are left out rather than guessed.
Larry Shaw
Exploratorium history states that staff member Larry Shaw created Pi Day in 1988.
Exploratorium
Exploratorium institutional history describes Pi Day as invented/created at the museum in 1988.
First documented observance
An Exploratorium-preserved interview with Larry Shaw and colleagues identifies March 14, 1988 as the first Pi Day.
The House supported the designation of Pi Day and encouraged schools and educators to observe it with mathematics and science activities.
U.S. House of Representatives · H.Res. 224 — Supporting the designation of Pi Day, and for other purposes
Exploratorium
The Exploratorium continues to celebrate and document Pi Day; this does not imply exclusive control over worldwide observance.
What the evidence establishes
Confirmed institutional roles and milestones are shown first. Details that could not be established from the reviewed sources are listed separately below.
4 fields not established in reviewed sources
Later institutional actions
Later recognition, renaming, mergers or date changes are kept separate from original establishment.
How to Observe Pi Day
Measure the circumference and diameter of several circular objects and compare the ratios.
Explore how pi appears in geometry, physics, engineering or probability at a level appropriate to the group.
Hold a pi-digit memory challenge, estimation game or circle-themed puzzle activity.
Use the day to make mathematics social and hands-on rather than treating memorization as the only way to participate.
Pi Day Facts
Pi Day is observed on March 14.
The Exploratorium credits Larry Shaw with creating Pi Day in 1988.
The first Exploratorium Pi Day was celebrated on March 14, 1988.
The U.S. House passed H.Res. 224 supporting Pi Day in 2009.
H.Res. 224 was a House resolution of support, not a law creating a standing federal public holiday.
Pi Day Messages
Happy Pi Day—March 14 is a chance to make mathematics curious, visible and fun.
Celebrate Pi Day by measuring a circle, solving a puzzle or discovering where pi appears in the world around you.
May Pi Day bring a little more curiosity to numbers, patterns and the pleasure of figuring things out.
Topic and context
What this page does not assume
- Keep the source-defined country, community, organizer or institutional scope; do not silently broaden it.
- Do not treat the title alone as proof of government recognition or public-holiday status.
- Do not add a creator, founding story or origin claim unless the supporting evidence establishes it.
Evidence & sources
Sources used across the guide are gathered here. Labels show how each source supports the page, and contextual references are kept separate from primary evidence.
GovInfo — H.Res. 224 supporting Pi Day (opens in a new tab)
Congressional Support Resolution
Exploratorium archive — 10 Questions for the Creators of Pi Day (opens in a new tab)
Exploratorium — 40th Anniversary Timeline (opens in a new tab)
Understand it, compare it, then explore further
Start with the most common factual questions, then compare closely related observances and explore useful connections.
Frequently asked questions
When is Pi Day?
14 March each year The documented recurrence rule is: 14 March.
Does Pi Day fall on the same date every year?
Yes. It uses a fixed annual date unless stronger evidence changes the pattern.
Is Pi Day an official public holiday?
The reviewed sources verify it within this scope: Mathematics education and public engagement / United States congressional recognition context. That recognition does not by itself make it a statutory public holiday; the site only makes public-holiday claims when reliable evidence explicitly does so.
Who established or recognizes Pi Day?
The reviewed sources identify Exploratorium as the proclaiming or establishing body. The proposer or originator is recorded separately as Larry Shaw. Current facilitation or coordination is recorded as Exploratorium.
Is Pi Day international or country-specific?
No single country is assigned to this observance. Its documented scope is: Mathematics education and public engagement / United States congressional recognition context. Use that scope rather than assuming worldwide or country-specific status.
How is this page verified?
The factual information is checked against reviewed sources, including the date pattern, scope and institutional history. This page was checked on 2026-09-07.
When is Pi Day?
Pi Day is observed on March 14.
Who created Pi Day?
The Exploratorium credits staff member Larry Shaw with creating the celebration in 1988.
Why is Pi Day on March 14?
In month/day notation March 14 is 3/14, matching the familiar 3.14 approximation of pi.
Did Congress make Pi Day a federal holiday?
No. In 2009 the U.S. House passed a resolution supporting the designation and encouraging educational observance; it did not create a federal public holiday.
Other observances on March 14
These observances are also listed on March 14, 2027.
Constitution Day
The Government of Andorra’s official embassy holiday calendar lists 14 March as Constitution Day.
Dog Theft Awareness Day
SAMPA identifies March 14 as its annual Dog Theft Awareness Day and maintains current prevention/recovery campaigning; the reviewed first-party material does not sufficiently establish the…
International Day of Action for Rivers
International Rivers states that participants at the first International Meeting of People Affected by Dams in Curitiba, Brazil, adopted the International Day of Action Against Dams and For…
International Day of Mathematics
National Write Your Story Day
National Day Calendar states that Mitzy founded the observance in 2017 and that the registrar proclaimed annual observance beginning March 14, 2018.
Professional Speakers Celebration Day
The Global Speakers Federation names March 14 as Professional Speakers Celebration Day annually, beginning in 2023, and its 2026 program again uses March 14.