When is tau day?

tau day is next on Saturday, June 28, 2025


Always know when is tau day. Figure out how many days till tau day. Holiday dates available for the next 10 years...
tau day

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Tau Day is celebrated on June 28th each year and is sometimes touted as Anti-Pi Day. On Tau Day, the science community observes tau as a ratio constant that explains the relationship between the radius and circumference of a circle. More recently, a movement to replace pi with tau circulated amongst scientists. Bob Palais was the first to call out pi in his article Pi is Wrong! Later, physicist Michael Hartl published a similar argument in the Tau Manifesto. This argument is not widely accepted or known but is gaining popularity within the math and science world. Many people are calling for the use of tau instead of pi in scientific-related fields.

Archimedes presumably first used tau in the third century. Born in the Greek city-state of Syracuse, Archimedes was one of the greatest scientists of the classical ages, and he calculated pi’s most precise numerical value. Centuries later, Palais and Hartl published articles stating why tau should be used in lieu of pi.

How To Celebrate Tau Day

Celebrate Tau Day by finding great new ways to incorporate math and science in your life. And if you’re a teacher, you can have fun educating your students about why #TauDay matters

How many days until tau day?

If you want to know how many more days, then here is your countdown to tau day

Upcoming dates for tau day


When is tau day 2024?Friday, June 28, 2024
When is tau day 2025?Saturday, June 28, 2025
When is tau day 2026?Sunday, June 28, 2026
When is tau day 2027?Monday, June 28, 2027
When is tau day 2028?Wednesday, June 28, 2028
When is tau day 2029?Thursday, June 28, 2029
When is tau day 2030?Friday, June 28, 2030
When is tau day 2031?Saturday, June 28, 2031
When is tau day 2032?Monday, June 28, 2032
When is tau day 2033?Tuesday, June 28, 2033
When is tau day 2034?Wednesday, June 28, 2034