Cutting Speed Calculator
Calculate cutting speed (Vc) from spindle RPM and diameter, or the spindle RPM needed to hit a target cutting speed — for turning, milling, and drilling.
Enter your values
Choose mode, then fill in the fields below.
How this calculator works
Cutting speed is the surface speed of the workpiece (turning) or tool (milling/drilling) at the point of cut:
D is diameter in millimeters, N is spindle speed in RPM, and Vc comes out in meters per minute. Rearranged to find the RPM needed for a target cutting speed:
Typical cutting speed ranges (turning, HSS/carbide)
| Material | Typical Vc (m/min) |
|---|---|
| Mild steel | 80 – 150 (carbide) |
| Stainless steel | 40 – 90 (carbide) |
| Aluminum | 200 – 500 (carbide) |
| Cast iron | 60 – 120 (carbide) |
These are general starting points — actual recommended cutting speed depends on the specific tool grade, coating, coolant, and cut depth. Check your tooling manufacturer's data for precise values.
Frequently asked questions
Does this apply to milling as well as turning?
Yes — for milling, D is the cutter diameter, and N is the spindle speed. The same Vc formula applies; only the diameter you use for "D" changes (workpiece for turning, cutting tool for milling).
How does this relate to feed rate?
Cutting speed sets the spindle RPM. Feed rate (how fast the tool advances) is a separate parameter — see the CNC chip load calculator to convert chip load per tooth into a table feed rate at a given RPM.