mechanical calculator
Cutting Speed & RPM Calculator
Convert between surface cutting speed (SFM) and spindle RPM for a tool or workpiece diameter - enter either one.
How it works
RPM = (SFM x 12) / (pi x D). SFM = (pi x D x RPM) / 12.
Worked example
1/2 in tool at 100 SFM: RPM = (100 x 12) / (pi x 0.5) = 764 rpm.
When to use it
- Enter the diameter plus either SFM or RPM; the other is solved.
- Look up the recommended SFM for your material and tool type.