A knitted Klein bottle hat with a twist.

This knit cap was lovingly and painstakingly knitted for me by my wonderful wife. She adapted the pattern from a similar hat showcased by Matt Parker.
In an fascinating presentation at the Royal Institute, Matt Parker claimed to have the nerdiest hat in the world.
First, if you haven’t done so, I encourage you to watch the entire presentation. It’s educational, entertaining, and simply amazing!
After hearing Matt discuss his custom hat, I approached my wife with an absurd idea. I wanted a custom version of the “nerdiest hat in the world”…that was…(wait for it)…even nerdier. With a bit of convincing she graciously agreed (Looking back I don’t think she realized the madness she had agreed to). After what seemed like endless counting, lots of measuring, a ton of frogging, and some artistic magic, the hat was finally ready.
I now surmise that THIS is the nerdiest hat in existence.
- Hat is knitted to size in the shape of a Klein Bottle.
- Vertical bands represent the number pi using alternating bands of yarn. The number of rows indicate the pi digit represented.
- The rim of the hat is lined with a binary sequence that spells out “I love you”
The hat is knitted with a total of four different colored yarns.
- Gray – Even pi digits
- Blue – Odd pi digits
- Yellow – Pi decimal point
- Turquoise – Binary message










If you’re interested in a Klein Bottle Hat of your own, the pattern is available for free at the link below.