Convert head circumference measurements to hat sizes across US numeric, UK, EU, and letter sizing systems. Whether you are buying a fitted baseball cap, a fedora, or a winter beanie, knowing your exact hat size prevents the frustration of returns. Measure around the widest part of your head, above your eyebrows and ears, for the most accurate result.
Measure above your eyebrows and ears, around the widest part of the back of your head.
| cm | US | UK | Letter |
|---|---|---|---|
| 53 | 6 5/8 | 6 1/2 | XS |
| 55 | 6 7/8 | 6 3/4 | S |
| 57 | 7 1/8 | 7 | M |
| 59 | 7 3/8 | 7 1/4 | L |
| 61 | 7 5/8 | 7 1/2 | XL |
| 63 | 7 7/8 | 7 3/4 | XXL |
Use a flexible measuring tape. Place it around your head about one centimeter above your eyebrows and ears, across the widest part of the back of your head. Keep the tape snug but not tight. Measure in centimeters for the most accurate conversion.
For fitted hats, round up to the next size. A slightly loose hat can be adjusted with hat sizing tape (adhesive foam strips inside the band). A hat that is too tight will be uncomfortable and leave marks.
Fitted hats come in specific sizes (like 7 1/4) with no adjustment mechanism. Adjustable hats have snapback, strapback, or flexfit bands that cover a range of sizes. Adjustable hats are more forgiving of imprecise measurements.
Yes, slightly. Hat sizing is more standardized than clothing, but some brands run slightly smaller or larger. Stetson, New Era, and Kangol each have minor variations. When in doubt, try before you buy or check the brand-specific size chart.
Slightly. Hat stretchers can add about half a size to wool, felt, and some cotton hats. Straw and synthetic hats are harder to stretch. Stretching beyond half a size risks distorting the shape.