Mad Hatter Day 2026
Wear a ridiculous hat for Mad Hatter Day! The date is fixed on October 6 — written 10/6 in the American month/day style — because Sir John Tenniel’s Mad Hatter illustration shows a hat ticket reading “In this style 10/6.”
About Mad Hatter Day
History & origins
Mad Hatter Day is observed every year on October 6. It is an unofficial fun holiday, not a government observance.
In Lewis Carroll’s Alice’s Adventures in Wonderland (1865), illustrated by Sir John Tenniel, the Hatter wears a top hat with a slip marked “In this style 10/6.” In Victorian Britain that meant a price of ten shillings and sixpence, not a calendar date. In 1986 a group of computer technicians in Boulder, Colorado, read 10/6 as October 6 in the U.S. date format and declared a day of silliness in the Hatter’s style. Early notices spread on computer networks; the idea has stayed as a light unofficial holiday roughly half a year from April Fools’ Day.
Carroll’s character is often called the Mad Hatter in popular speech; the book usually calls him the Hatter. The older English phrase “mad as a hatter” is commonly linked to mercury poisoning among historical hat-makers who used mercuric nitrate in felting — background color for the joke, not the 1986 calendar invention.
Why it matters
The day is permission for harmless nonsense: a hat, a tea party, a riddle with no answer. It also teaches a small literacy lesson — that Tenniel’s “10/6” was money first, and only later a U.S. date gag.
How to celebrate
Wear a hat that would get you stared at on an ordinary Tuesday. Host a short tea with mismatched cups. Read the Mad Tea-Party chapter aloud. Tell a riddle and refuse to solve it. Keep it kind; silliness is not an excuse to embarrass someone who did not ask to play.
Facts
- Tenniel’s Hatter hat slip reads “In this style 10/6,” originally a price of ten shillings and sixpence
- Boulder, Colorado, computer technicians began Mad Hatter Day as a silliness holiday in 1986
- The U.S. reading of 10/6 as October 6 does not match the British day/month date order
- Alice’s Adventures in Wonderland was published in 1865
- The day is unofficial fun, not a federal or UN observance
Upcoming dates
- Tuesday, October 6, 2026
- Wednesday, October 6, 2027
- Friday, October 6, 2028
- Saturday, October 6, 2029
- Sunday, October 6, 2030
Frequently asked questions
When is Mad Hatter Day in 2026?
Mad Hatter Day in 2026 falls on Tuesday, October 6, 2026.
Is today Mad Hatter Day?
No. Mad Hatter Day in 2026 falls on Tuesday, October 6, 2026, not today.
What is Mad Hatter Day?
It is an unofficial day of silliness inspired by the Mad Hatter from Alice’s Adventures in Wonderland and by the “10/6” label on Tenniel’s hat illustration.
Who started Mad Hatter Day?
A group of computer technicians in Boulder, Colorado, started the observance in 1986 as a day of good-natured nonsense.
How do you celebrate Mad Hatter Day?
Wear a wild hat, share tea and riddles, or read the tea-party chapter. Keep the joke gentle and optional for everyone involved.
Is Mad Hatter Day an official holiday?
No. It is not a U.S. federal holiday and not a United Nations day. Offices and schools follow their usual schedules.
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