Allen Wrench Size Chart

Allen wrench size chart explained below consists of the hex size, suitable long arm length and also short arm length. It is designed to help you in the workshop and use a proper Allen wrench when needed. Keep in mind that wrenches made from stainless steel won’t corrode or rust regardless of how and where they are used. This material is immune to rusk completely. This is important due to the fact the wrench will always maintain its size.

The tables below are basically identical but available in different measurements. The first one is millimeters or metric while the second is in inches, imperial size chart. The third table is related to more specific Allen keys and it shows the correlation between the hex size in inches and the long/short arm ibn millimeters. The first two charts refer to stainless steel models. The third is based for different materials and for models with the round head (used to make insertion much easier). See also digital torque wrench review.

Stainless Allen Keys Metric

Hex size	Long arm lenght	Short arm lenght
1.5 mm	90 mm	14 mm
2 mm	112 mm	19 mm
2.5 mm	101 mm	16 mm
3 mm	123 mm	21 mm
4 mm	137 mm	24 mm
5 mm	154 mm	27 mm
6 mm	172 mm	31 mm
8 mm	195 mm	37 mm
10 mm	224 mm	42 mm

Stainless Allen Keys Imperial

Hex size	Long arm lenght	Short arm lenght
3/32 inch	112 mm	19 mm
7/64 inch	119 mm	20 mm
1/8 inch	123 mm	21 mm
9/64 inch	130 mm	22 mm
5/32 inch	137 mm	24 mm
3/16 inch	154 mm	27 mm
1/4 inch	185 mm	34 mm
5/16 inch	195 mm	37 mm
3/8 inch	224 mm	42 mm

Allen Keys Imperial

Hex size	Long arm lenght	Short arm lenght
0.05 inch	83 mm	14 mm
1/16 inch	91 mm	15 mm
5/64 inch	100 mm	16 mm
3/32 inch	112 mm	18 mm
7/64 inch	119 mm	19 mm
1/8 inch	126 mm	20 mm
9/64 inch	132 mm	23 mm
5/32 inch	140 mm	25 mm
3/16 inch	160 mm	25 mm
7/32 inch	180 mm	27 mm
1/4 inch	190 mm	34 mm
5/16 inch	200 mm	36 mm
1/2 inch	224 mm	40 mm