Hat Size Converter
Convert hat sizes between US, UK, EU, and head circumference in cm and inches.
Covers baseball caps, fedoras, beanies, and formal hats.
Type in any field — the others update instantly.
Hat sizes are based on head circumference, but each region uses a different scale.
US hat sizes are based on the diameter of a circle with the same circumference.
- US size = circumference (inches) / π (3.14159)
UK hat sizes use the same system as US sizes.
EU hat sizes equal the head circumference in centimeters.
Conversion formulas:
- 1 inch = 2.54 cm (exact)
- US/UK size = circumference in inches / π
Common hat sizes:
| US/UK | EU | Circumference (cm) | Circumference (in) |
|---|---|---|---|
| 6-3/4 | 54 | 54 cm | 21.3" |
| 6-7/8 | 55 | 55 cm | 21.7" |
| 7 | 56 | 56 cm | 22.0" |
| 7-1/8 | 57 | 57 cm | 22.4" |
| 7-1/4 | 58 | 58 cm | 22.8" |
| 7-3/8 | 59 | 59 cm | 23.2" |
| 7-1/2 | 60 | 60 cm | 23.6" |
| 7-5/8 | 61 | 61 cm | 24.0" |
| 7-3/4 | 62 | 62 cm | 24.4" |
Measure around the widest part of your head, just above the ears.