Allen Keys work with the following fasteners:
Some of the main benefit of the Allen Wrench include:
US Short Arm Hex / Allen Key Sizes (ASME B18.3-2012) |
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| Hex Key Size | Min Width Across Flats | Length of Short Section | Length of Long Section | ||
| Max | Min | Max | Min | ||
| 0.028" | 0.0275" | 0.312" | 0.125" | 1.312 | 1.125 |
| 0.035" | 0.0345" | 0.438" | 0.250" | 1.312 | 1.125 |
| 0.050" | 0.049" | 0.625" | 0.438" | 1.75 | 1.562 |
| 1/16" | 0.0615" | 0.656" | 0.469" | 1.844 | 1.656 |
| 5/64" | 0.0771" | 0.703" | 0.516" | 1.969 | 1.781 |
| 3/32" | 0.0927" | 0.750" | 0.562" | 2.094 | 1.906 |
| 7/64" | 0.1077" | 0.797" | 0.609" | 2.219 | 2.031 |
| 1/8" | 0.1235" | 0.844" | 0.656" | 2.344 | 2.156 |
| 9/64" | 0.1391" | 0.891" | 0.703" | 2.469 | 2.281 |
| 5/32" | 0.1547" | 0.938" | 0.750" | 2.594 | 2.406 |
| 3/16" | 0.1860" | 1.031" | 0.844" | 2.844 | 2.656 |
| 7/32" | 0.2172" | 1.125" | 0.938" | 3.094 | 2.906 |
| 1/4" | 0.2480" | 1.219" | 1.031" | 3.344 | 3.156 |
| 5/16" | 0.3110" | 1.344" | 1.156" | 3.844 | 3.656 |
| 3/8" | 0.3730" | 1.469" | 1.281" | 4.344 | 4.156 |
| 7/16" | 0.4355" | 1.594" | 1.406" | 4.844 | 4.656 |
| 1/2" | 0.4975" | 1.719" | 1.531" | 5.344 | 5.156 |
| 9/16" | 0.5600" | 1.844" | 1.656" | 5.844 | 5.656 |
| 5/8" | 0.6225" | 1.969" | 1.781" | 6.344 | 6.156 |
| 3/4" | 0.7470" | 2.219" | 2.031" | 7.344 | 7.156 |
| 7/8" | 0.8720" | 2.469" | 2.281" | 8.344 | 8.156 |
| 1" | 0.9970" | 2.719" | 2.531" | 9.344 | 9.156 |
Metric Short Arm Hex / Allen Key Sizes (DIN 911) |
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| Hex Key Size | Min Width Across Flats | Length of Short Section | Length of Long Section | ||
| Max | Min | Max | Min | ||
| M0.9 | 0.876mm | 11mm | 6mm | 34mm | 28mm |
| M1.3 | 1.244mm | 16mm | 11mm | 44mm | 39mm |
| M1.5 | 1.470mm | 14mm | 13mm | 45mm | 43mm |
| M2 | 1.970mm | 16mm | 15mm | 50mm | 48mm |
| M2.5 | 2.470mm | 18mm | 17mm | 56mm | 53mm |
| M3 | 2.960mm | 20mm | 18mm | 63mm | 60mm |
| M4 | 3.960mm | 25mm | 23mm | 70mm | 66mm |
| M5 | 4.960mm | 28mm | 26mm | 80mm | 76mm |
| M6 | 5.950mm | 32mm | 30mm | 90mm | 86mm |
| M8 | 7.950mm | 36mm | 34mm | 100mm | 95mm |
| M10 | 9.950mm | 40mm | 38mm | 112mm | 106mm |
| M12 | 11.950mm | 45mm | 43mm | 125mm | 119mm |
| M14 | 13.930mm | 56mm | 53mm | 140mm | 133mm |
| M17 | 16.930mm | 63mm | 60mm | 160mm | 152mm |
| M19 | 18.930mm | 70mm | 67mm | 280mm | 271mm |
Note:
While it might seem logical to assume that a screw would take the same size hex key as the screw size (that a M4 button head would take a M4 hex key for example), but in action the screw size relates to the screw diameter, just as with the hex key. The socket recess is a very different size and is different from screw type to screw type as shown here.