Common Hex Key Sizes

For example 4 mm keys are almost exactly the same size as 5 32 and 8 mm keys are almost exactly the same size as 5 16 which makes 4 mm and 8 mm preferred numbers for consumer products such as self assembly furniture because end users can successfully use an imperial key on a metric fastener or vice versa without stripping.

Common hex key sizes.

Also a standard size. Common inch sizes are 5 64 3 32 7 64 1 8 9 64 5 32 3 16 7 32 and inch. Also some of the smallest sae imperial key sizes are given in decimal inch sizes instead of inch fractions. Just to diverge a moment torx is an alternate socket style.

Width w depth t 5 16 7 16 3 32 3 64 3 32 3 32 1 2 9 16 1 8 1 16 1 8 1 8 5 8 7 8 3 16 3 32 3 16 3 16 15 16 1 1 4 1 4 1 8 1 4 1 4 1 5 16 1 3 8 5 16 5 32 5 16 5 16 1 7 16 1 3 4 3 8 3 16 3 8 3 8 1 13 16 2 1 4 1 2 1 4 1 2 1 2 2 5 16 2 3 4 5 8 5 16 5 8 5 8 2 13 16 3 1 4 3 4 3 8 3 4 3 4 3 5 16 3 3 4 7 8 7 16 7 8 7 8 3 13 16 4 1 2 1 1 2 1 1 4 9 16. Hex key sizes mm notes compares standard and metric allen wrench sizes where they closely match and where they don t wrench equivalence 15 key set. Allen wrenches are convenient and helpful. Imperial hex key sizes are based on fractions of 64 and reduced fractions thereof and some searching around to see what is common.

Of these sizes some of the more popular ones are 2 5 mm 3 mm 4 mm 5 mm 6 mm 8 mm 10 mm. There are a few ways that you can tell what hex key you may need to finish a project tighten a set of screws or loosen an old screw. Interchangable 0 028 and 0 7mm. Many fractions seems to be omitted such as 11 64 13 64 15 64 17 64 9 32 19 64 21 64 11 32 23 64 and 25 64.

If you aren t sure what size you need an allen wrench size chart can be a handy tool to get you on your way. Interestingly some of the smallest imperial key sizes are very close to the dimensions of small metric keys such. In addition to the precision sizes mentioned above the common metric allen wrench sizes are 1 5 mm 2 mm 2 5 mm 3 mm 4 mm 4 5 mm 5 mm 5 5 mm 6 mm 7 mm 8 mm 9 mm 10 mm. Interchangable 0 035 and 0 9mm.

Also a standard size. David rome immediate media park tool made this style which places three of the most common sizes into one tool famous and mechanics around the world still naturally reach for it. 19 mm keys are so close to the same size as that they are completely interchangeable in practical use. Hex keys are defined in both metric and sae society of automotive engineers inch sizes.