Use a thread gauge to identify the pitch
Measure the outside diameter of male threads with calipers
Measure the inside diameter of female threads with calipers
Count the number of threads per inch for imperial threads
Measure the distance between threads for metric threads
Compare the measurements to a thread size chart
Check whether the thread is straight or tapered
Verify the thread standard if needed, such as UNC, UNF, BSP, or metric
Record the diameter, pitch, and thread type