Hat sizing systems vary widely between countries. This converter covers US fractional sizes, EU/metric circumference sizes, and Soviet GOST hat sizes.
| EU/cm | US | UK | USSR/RU |
|---|---|---|---|
| 52 | 6½ | 6½ | 52 |
| 53 | 6⅝ | 6⅝ | 53 |
| 54 | 6¾ | 6¾ | 54 |
| 55 | 6⅞ | 6⅞ | 55 |
| 56 | 7 | 7 | 56 |
| 57 | 7⅛ | 7⅛ | 57 |
| 58 | 7¼ | 7¼ | 58 |
| 59 | 7⅜ | 7⅜ | 59 |
| 60 | 7½ | 7½ | 60 |
| 61 | 7⅝ | 7⅝ | 61 |
| 62 | 7¾ | 7¾ | 62 |
How Hat Sizes Work
US hat sizes are the hat's interior diameter in inches (circumference ÷ π). EU sizes use head circumference in centimetres directly. Soviet/Russian sizes also use centimetres, making them equivalent to EU hat sizes.