Sometimes it is not possible to use a thread measuring micrometer to measure screw threads, so the measure over three wire method must be used.
Use this application to quickly and easily do all the calculations required to measure ISO metric and UN 60 degree threads, Acme and Stub Acme threads, and Trapezoid threads with wires. The only thing it can't do is help you to hold the three wires in place AND use the micrometer at the same time!
You start with the nominal thread size, thread pitch (or TPI) and wire size.
You cancalculate pitch diameter or measurement over wires or both.
The thread measurement over wires calculator will also give you the best wire size.