How To Measure Thread Size With Caliper. Use a ruler or tape measure to measure the inner diameter of the pipe. The first step to identify thread sizes of your components is measuring the diameter.
Hold the pipe in 1 hand and take a ruler or tape measure in your other hand. Use a caliper, measuring tape, or ruler to measure the thread diameter of a male thread or female thread. When determining the diameter, you have to make sure that the slide is placed on the thread and not accidentally slip between the cutting edges.
How to measure threads 1.) first, use a combination o.d./i.d.
Measure the distance across the flat sides of the bolt head using the vernier caliper. Simply insert the trial gauges into the threads until the gauge fits perfectly. This section contains tables of sizes for metric thread hardware. Match the measurement to the thread chart.