How the calculator works
The calculator turns your head circumference into a fitted size by dividing it by pi, the same way hatters have sized hats for over a century. From there it works out the UK size (one eighth smaller), the European size (your circumference in centimetres) and the letter size.
It then checks your measurement against the size ranges published by New Era, Flexfit, Nike, Stetson and other brands, because letter and stretch-fit sizes differ from brand to brand.
What size hat do I wear?
- Under 56 cm (22 in): 6 ⅞ or smaller, usually XS or S.
- 56 to 57 cm (22 to 22 ½ in): 7 to 7 ⅛, usually M.
- 58 to 59 cm (22 ⅞ to 23 ¼ in): 7 ¼ to 7 ⅜, usually L.
- 60 to 61 cm (23 ⅝ to 24 in): 7 ½ to 7 ⅝, usually XL.
- 62 cm (24 ⅜ in) and over: 7 ¾ and up, XXL or 3XL.
| cm | Inches | US | UK | Letter |
|---|---|---|---|---|
| 46 | 18 ⅛ | 5 ¾ | 5 ⅝ | – |
| 47 | 18 ½ | 5 ⅞ | 5 ¾ | – |
| 48 | 18 ⅞ | 6 | 5 ⅞ | – |
| 49 | 19 ¼ | 6 ⅛ | 6 | – |
| 50 | 19 ⅝ | 6 ¼ | 6 ⅛ | – |
| 51 | 20 ⅛ | 6 ⅜ | 6 ¼ | – |
| 52 | 20 ½ | 6 ½ | 6 ⅜ | XS |
| 53 | 20 ⅞ | 6 ⅝ | 6 ½ | XS |
| 54 | 21 ¼ | 6 ¾ | 6 ⅝ | S |
| 55 | 21 ⅝ | 6 ⅞ | 6 ¾ | S |
| 56 | 22 | 7 | 6 ⅞ | M |
| 57 | 22 ½ | 7 ⅛ | 7 | M |
| 58 | 22 ⅞ | 7 ¼ | 7 ⅛ | L |
| 59 | 23 ¼ | 7 ⅜ | 7 ¼ | L |
| 60 | 23 ⅝ | 7 ½ | 7 ⅜ | XL |
| 61 | 24 | 7 ⅝ | 7 ½ | XL |
| 62 | 24 ⅜ | 7 ¾ | 7 ⅝ | XXL |
| 63 | 24 ¾ | 7 ⅞ | 7 ¾ | XXL |
| 64 | 25 ¼ | 8 | 7 ⅞ | 3XL |
| 65 | 25 ⅝ | 8 ⅛ | 8 | 3XL |
| 66 | 26 | 8 ¼ | 8 ⅛ | 3XL |
Fit tips
- Measure two or three times and use the largest number.
- Type the exact decimal, such as 57.5 cm or 22.6 in. The calculator rounds for you.
- If the US result shows an arrow (↑), you are between sizes. Take the larger size for fitted caps.