Hat Size Chart and Head Circumference Converter
Hat sizes come from head circumference. Europe and most of Asia label the circumference directly in centimetres (56, 57, 58), the US and UK divide the circumference in inches by pi to get sizes like 7 1/8 or 7 1/4, and casual caps collapse everything into S/M/L/XL. A 57 cm head is US 7 1/8, UK 7, EU 57 and a medium in most cap brands. Fitted baseball caps from New Era use the US fractional scale.
Measure with a soft tape around the widest part of the head, about 1 cm above the ears and across the middle of the forehead, keeping the tape level and snug but not tight. Round up to the nearest half centimetre. If you have thick hair or wear the hat over a beanie, add 1 cm. Structured hats such as fedoras and fitted caps need the exact size; adjustable and knit hats cover a 3 to 4 cm range and are forgiving.
Size chart
| Head (cm) | Head (in) | US | UK | International |
|---|---|---|---|---|
| 52 | 20 1/2 | 6 1/2 | 6 3/8 | XS |
| 53 | 20 7/8 | 6 5/8 | 6 1/2 | XS |
| 54 | 21 1/4 | 6 3/4 | 6 5/8 | S |
| 55 | 21 5/8 | 6 7/8 | 6 3/4 | S |
| 56 | 22 | 7 | 6 7/8 | M |
| 57 | 22 1/2 | 7 1/8 | 7 | M |
| 58 | 22 7/8 | 7 1/4 | 7 1/8 | L |
| 59 | 23 1/4 | 7 3/8 | 7 1/4 | L |
| 60 | 23 5/8 | 7 1/2 | 7 3/8 | XL |
| 61 | 24 | 7 5/8 | 7 1/2 | XL |
| 62 | 24 3/8 | 7 3/4 | 7 5/8 | XXL |
| 63 | 24 3/4 | 7 7/8 | 7 3/4 | XXL |
| 64 | 25 1/4 | 8 | 7 7/8 | XXL |
Sizes are approximate and vary by brand
Frequently Asked Questions
What hat size is a 58 cm head?▾
58 cm is US 7 1/4, UK 7 1/8, EU 58, and a Medium to Large in S/M/L brands. In inches it is 22 7/8. Adult heads range from about 53 cm to 64 cm, with 57 to 58 cm the most common.
How is the US hat size calculated?▾
Head circumference in inches divided by 3.14. A 22.5 in (57 cm) head gives 7.16, rounded to 7 1/8. Each 1/8 step in US size equals about 1 cm of circumference. UK sizes are 1/8 smaller than US for the same head.
What do S, M, L mean in hat sizes?▾
Typically S is 55 to 56 cm, M is 57 to 58 cm, L is 59 to 60 cm, XL is 61 to 62 cm. Some brands shift by 1 cm, so check the brand's own chart when buying fitted styles.
Should I size up if my measurement is between two sizes?▾
For structured hats, yes: a tight hat causes headaches and cannot be stretched much. Felt hats can be reduced slightly with sizing tape (foam inserts), so ordering up and padding is safer than ordering down.
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