About the Cutting Speed Calculator
Convert between cutting speed (SFM or m/min) and spindle RPM for turning and milling.
Also known as: sfm calculator, surface feet per minute, machining speed, spindle speed calculator.
How to use this calculator
- Enter calculate, tool or work diameter.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
RPM = 1000 × Vc / (π × D)
Worked example
Using the values pre-filled in the calculator above:
- Calculate: Spindle RPM
- Tool or work diameter = 20 mm
- Cutting speed = 100 m/min
the calculator returns:
- Spindle speed: 1,592 RPM
- Cutting speed in SFM: 328.1
- Nearest 50 RPM: 1,600