Metric Bolt Heads and Wrench Sizes
ANSI/SO, DIN and JIS bolts.
ANSI/ISO, DIN and JIS metric bolt head and wrench sizes:
| ISO Metric Threaded Bolt (mm) | Spanner or Wrench Size (mm) | Allen Key (mm) | ||
|---|---|---|---|---|
| ANSI/ISO | DIN | JIS | ANSI/ISO | |
| 3 | 5.5 | |||
| 4 | 7 | 7 | 7 | |
| 5 | 8 | 8 | 8 | 4 |
| 6 | 10 | 10 | 10 | 5 |
| 7 | 11 | |||
| 8 | 13 | 13 | 12 | 6 |
| 10 | 15, 16 | 17 | 14 | 8 |
| 12 | 18 | 19 | 17 | 10 |
| 14 | 21 | 22 | 19 | |
| 16 | 24 | 24 | 22 | 14 |
| 18 | 27 | |||
| 20 | 30 | 30 | 17 | |
| 24 | 36 | 19 | ||
- ANSI B18.2.3.9M Metric Heavy Hex Flange Screws
- ISO 4228 Spanners and wrenches -- Spline drive ends for power socket wrenches
- ISO 724 - Metric Threads
An Allen key, Allen wrench or hex key is a tool used to drive bolts and screws with hexagonal sockets in their heads.
