Thread Calculator
Calculates the Diameter for an Internal Thread

The Thread Calculator was designed to help you calculate the diameter for an internal thread. You only need to provide two inputs; the outside diameter of the external thread, and the threads per inch that you are using. Once you enter these values and press the calculate button the bore diameter for the internal thread will be provided.

Click here to see how it works and check out the threading chart

Enter the outside diameter of your external thread (in decimal):  

Select the Threads Per Inch (TPI)::   4 8 12 16 24 32 36 48

Thread Calculator
Calculates the Diameter for an External Thread

The Thread Calculator was designed to help you calculate the diameter for an external thread. You only need to provide two inputs; the inside diameter of the internal thread, and the threads per inch that you are using. Once you enter these values and press the calculate button the diameter for the external thread will be provided.

Click here to see how it works and check out the threading chart

Enter the inside diameter of your internal thread (in decimal):  

Select the Threads Per Inch (TPI)::   4 8 12 16 24 32 36 48

Note:

Multiple Leads – when calculating either the female bore or the male diameter and which thread depth when making multiple lead threads use the total number of threads per inch; for instance, when using an 8 TPI chaser with 2 leads you would use the figures for 16 TPI.

Grain Alignment - when figuring the pitch using multiple lead threads for purposes of grain alignment etc. use the pitch figure for the chaser's TPI. For instance, for the 8 TPI thread with 2 leads the pitch would still be 0.125".