Hat Size Converter
Hat size between cm, inches, US, UK, and S/M/L.
Cm
57
Inches
22.375
Letter
M
US
7 1/8
UK
7
Measure around the head about 1 cm above the eyebrows and ears, where a hat would sit. US sizes are circumference in inches divided by π (so US 7 ≈ 22 inches around). For brimmed hats, round up if you're between sizes.
About
Convert hat sizes across the major systems. Accepts head circumference in cm or inches, US fractional sizes (7 1/8), UK sizes, and letter sizes (S/M/L).
How to use
- Measure around your head 1 cm above eyebrows.
- Pick the system.
- Type the value.
FAQ
How does US sizing work?+
US hat size is circumference (in inches) divided by π. So 22 in around / π ≈ 7. That's why US sizes go in 1/8-in steps.