A bolt diameter measurement is used to match the size of a washer and a nut to that specific bolt. For example, as a very basic measurement, a 3/8-inch measured bolt diameter will always support a 3/8-inch washer and will also support a 3/8-inch nut, provided the thread patterns match. Both the washer and the nut will have an inner hole diameter of 3/8-inch which will correctly match the outer diameter of the bolt.
Things You'll Need
- Tape measure
Locate the shank on the bolt to be measured. This will be the area directly under the bolt head that has not been turned with threads.
Measure from one side of the bolt shank to the other side with a tape measure. This will give you the proper bolt diameter measurement.
Measure across the threads at the bottom of a bolt that is threaded all the way up the shank. This is called the "major diameter" and is considered that exact same measurement as the shank diameter.
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