A screw is a much more complex tool than it looks. It has an odd shape that is uneven and difficult to measure. The best way to do this is with the use of thread measuring wire. Measuring the thread of a screw is very important because it will determine how and where a contractor, electrician, or other profession that uses screws, will use these screws and what tools are the right ones to work with them.

First, it is important to know the anatomy of a screw before knowing why and how to measure one. If you could take a screw (or its more formal derivation, the bolt) and unwind its thread, you would find one of the simplest of devices: an inclined plane. The inclined plane is there mainly to pull the screw shaft into the wood or metal. The holding power comes about because the screw acts as a spring. The part that the screwdriver enters is known as the head. This is an important piece to keep in tact, as a stripped head can make life very difficult. The shank is the piece directly below that, before the threads start. This is the main support for the screw. The piece following that is the helical thread that is the most recognizable feature of a screw. The point that is driven into the surface is known as the gimlet point.

Now that the basics are covered, knowing how to perform the process of thread measuring can be explained. The most commonly used, probably because of it's accuracy, is thread measuring wire. This is a device that allows one to measure the pitch diameter of the threads of a bolt or screw. There are numerous different methods of measuring this pitch diameter. One of the most popular of these thread measuring methods is the three-wire method. Performing this involves the use of three thread measuring wire to observe a very accurate measurement of a screw or bolt's thread's pitch diameter.

Many of these techniques are better for special situations but the three-wire technique has become the most widely used method. Once this measurement is obtained, the professional then makes an informed decision about the next course of action. This measurement will affect the types of tools used and also how the screws are used. Different pitch diameters can have a great affect on how a task will have to be handled.