Allen Key (Also known equally Hex Key, Hexagon Key, Socket Key, LN Key), sizes as well as its dimensions tin endure real handy piece designing as well as selecting fasteners for your application. These dimensions of allen keys tin endure used to banking concern check the accessibility of your bolts were infinite is limited. For event for an M8 socket caput cap screw nosotros remove at to the lowest degree 32+8(head size) = 40mm clearance higher upwards the screw for slow accessibility. Refer the next tabular array for metric allen fundamental sizes as well as dimensions for corresponding socket caput cap screw based on ISO 4762/DIN 912 standards.
| Screw Size | Allen Key Size, s | A | B |
| M3 | 2.5 | 56 | 18 |
| M4 | 3 | 63 | 20 |
| M5 | 4 | 70 | 25 |
| M6 | 5 | 80 | 28 |
| M8 | 6 | 90 | 32 |
| M10 | 8 | 100 | 36 |
| M12 | 10 | 112 | 40 |
| M14 | 12 | 125 | 45 |
| M16 | 14 | 140 | 56 |
| M18 | 14 | 140 | 56 |
| M20 | 17 | 160 | 63 |
| M22 | 17 | 160 | 63 |
| M24 | 19 | 180 | 70 |