Enter the cutting speed and threads per inch into the calculator to determine the threading RPM. This calculator can also evaluate any of the variables given the others are known.

Threading Rpm Formula

The following formula is used to calculate the threading RPM (Revolutions Per Minute). Variables:

RPM = (CS * 12) / TPI
  • RPM is the threading speed in revolutions per minute
  • CS is the cutting speed in feet per minute
  • TPI is the threads per inch

To calculate the threading RPM, multiply the cutting speed by 12, then divide the result by the threads per inch. This will give you the threading speed in revolutions per minute.

What is a Threading Rpm?

Threading RPM (Revolutions Per Minute) refers to the speed at which a tool or machine, typically a lathe or milling machine, rotates when cutting threads into a material. The RPM is a crucial factor in threading as it impacts the quality of the threads and the tool’s lifespan. It is determined based on the type of material being threaded, the type of tool being used, and the desired thread size and quality.

How to Calculate Threading Rpm?

The following steps outline how to calculate the Threading RPM.

  1. First, determine the cutting speed (CS) in feet per minute.
  2. Next, determine the threads per inch (TPI).
  3. Next, use the formula RPM = (CS * 12) / TPI to calculate the Threading RPM.
  4. Finally, calculate the Threading RPM.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Cutting speed (CS) = 120 feet per minute

Threads per inch (TPI) = 8