| Bolt Diameter | Head Wrench Size |
| (mm) | (mm) |
| ANSI/ISO | DIN | JIS | DIN/ISO | |
| Heavy Hex | ||||
| 4 | 7 | 7 | 7 | – |
| 5 | 8 | 8 | 8 | – |
| 6 | 10 | 10 | 10 | – |
| 7 | – | 11 | – | – |
| 8 | 13 | 13 | 12 | – |
| 10 | 16 | 17 | 14 | – |
| 12 | 18 | 19 | 17 | 22/21* |
| 14 | 21 | 22 | 19 | – |
| 16 | 24 | 24 | 22 | 27 |
| 18 | – | 27 | – | – |
| 20 | 30 | 30 | – | 34/32* |
| ANSI – American National Standards Institute |
| ISO – International Organization for Standardisation |
| DIN – Deutsches Institut für Normung |
| JIS – Japanese Industrial Standard |
| * Indicates ISO standard. |