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 sizeLong arm lenghtShort arm lenght
1.5 mm90 mm14 mm
2 mm112 mm19 mm
2.5 mm101 mm16 mm
3 mm123 mm21 mm
4 mm137 mm24 mm
5 mm154 mm27 mm
6 mm172 mm31 mm
8 mm195 mm37 mm
10 mm224 mm42 mm

Stainless Allen Keys Imperial

Hex sizeLong arm lenghtShort arm lenght
3/32 inch112 mm19 mm
7/64 inch119 mm20 mm
1/8 inch123 mm21 mm
9/64 inch130 mm22 mm
5/32 inch137 mm24 mm
3/16 inch154 mm27 mm
1/4 inch185 mm34 mm
5/16 inch195 mm37 mm
3/8 inch224 mm42 mm

Allen Keys Imperial

Hex sizeLong arm lenghtShort arm lenght
0.05 inch83 mm14 mm
1/16 inch91 mm15 mm
5/64 inch100 mm16 mm
3/32 inch112 mm18 mm
7/64 inch119 mm19 mm
1/8 inch126 mm20 mm
9/64 inch132 mm23 mm
5/32 inch140 mm25 mm
3/16 inch160 mm25 mm
7/32 inch180 mm27 mm
1/4 inch190 mm34 mm
5/16 inch200 mm36 mm
1/2 inch224 mm40 mm

Here is a trick when using an Allen Wrench you might not have known about: