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Socket Size Inch & Metric, Download Quick Convert Sheet Between SAE and Imperial Socket Sizes

  • 2016-02-19

How to Convert Between SAE and Imperial Socket Sizes? 

There are two different methods for measuring the hex sizes of sockets. The SAE (Society of Automotive Engineers) system uses inches, and the imperial or metric system uses millimeters.

At the hardware store, you may find yourself asking: “Why doesn’t this socket fit this nut? They appear to be very close in size!”

If you lack a clear understanding of socket sizing, it’s easy to choose the wrong tool. Without a tool of the correct size, you won’t be able to properly fix or lock the nut. How can you tell which one is the right size?

Many customers admit that they don’t know exactly how to convert between SAE (inches) and imperial or metric (millimeters) measurements. For example, what is the actual size difference between a 11/16" hex nut and a 17mm hex nut? Will both sizes fit a 17mm socket?

The conversion chart below shows the correlation between SAE (inches) and imperial (mm) measurements.


Tien-I has more than a decade of experience designing and manufacturing hand tools, impact sockets and OEM items to fulfill its customers’ specific demands. If you have any special design requirements, please get in touch with our sales team today.


The table below shows conversion from millimeters to inches and vice versa. (Please note that these are approximate values, intended for making rough calculations)

Metric and SAE by Tien-i

 (Click above pic to download PDF)


(Click above pic to download PDF)