Calculate spindle speed from cutting speed and tool diameter.
Using the calculator
Enter values that match the tool, material and operation. Check the unit beside each field before calculating.
Calculation
For metric inputs, spindle RPM = (1000 × cutting speed) ÷ (π × diameter).
Reading the result
The result follows the relationship shown on this page. Final shop settings also depend on material, tool geometry, workholding, machine capability, coolant and the actual cut.
Worked example
For example, 250 m/min cutting speed with a 10 mm diameter gives about 7,958 RPM.