Engineering Tools

Feeds & Speeds Calculator

Turn a recommended surface speed into a spindle RPM and feed rate for milling or drilling. Pick the workpiece material and tool material for a starting surface speed, then dial in tool diameter, flutes and chip load.

Workpiece material

Tool material

Tool diameter in

Flutes / teeth

Chip load in/tooth

Surface speed SFM

Spindle speed

0RPM

Feed rate

0 in/min

Feed rate (alt)

0 mm/min

Surface speed

0 m/min

The formulas used

Spindle speed comes from surface speed and tool diameter: RPM = (SFM × 12) / (π × D) in inch units, where D is the tool diameter in inches. Feed rate is then feed = RPM × flutes × chip load. Surface speed in metric is the cutting speed Vc in meters per minute (Vc = SFM × 0.3048). Selecting a material loads a typical starting surface speed for the chosen tool material — these are conservative midpoints; raise or lower them based on your setup rigidity, coolant, depth of cut and finish requirements.

Typical surface speeds (SFM)

Material	HSS	Carbide

These are starting points for general milling and drilling, not optimized cutting data. Always confirm against your tool manufacturer's recommendations and your machine's capability, and step in gradually on unfamiliar setups.

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