Milling Speeds & Feeds Calculator

Spindle RPM and table feed rate for end mills — set material, cutter diameter, flutes and chip load per tooth.

Spindle speed

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Feed rate

Chip load / tooth

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Inputs

Material

Cutter type

Cutting speed (m/min)

Set automatically from material × cutter type. Switch material to "Custom" to override.

Cutter diameter (mm)

Number of flutes

Chip load per tooth (mm)

Typical range: 0.02-0.04mm for small cutters/hard materials, up to 0.10-0.15mm for large cutters/soft materials.

Results

Spindle speedRPM = CS × 1000 ÷ (π × Ø)

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Table feed rateRPM × flutes × chip load

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Cutting speed used

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Feed per revolution

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If chatter appears, reduce chip load or check cutter runout and workholding before reducing speed.

How this is calculated

Spindle RPM uses the same surface-speed formula as drilling: RPM = (cutting speed × 1000) ÷ (π × cutter diameter). Table feed rate, however, is driven by chip load rather than a single feed-per-revolution figure, since a milling cutter removes material with multiple teeth per revolution: Feed rate (mm/min) = RPM × number of flutes × chip load per tooth. More flutes or a higher chip load both increase feed rate for the same RPM.

Chip load recommendations vary more by cutter and coating than drilling feed does — treat the default as a starting point and adjust based on chatter, finish and chip colour. For the equivalent drilling calculation, see the drilling speeds & feeds calculator, or read the full speeds and feeds guide for how the underlying RPM formula works.

Estimates for guidance only — always check your cutter manufacturer's recommended chip load and adjust for machine rigidity, workholding and finish requirements.