How to use this calculator
- Choose what to solve for. Pick whether you know the chip load (and want the feed rate) or the feed rate (and want the chip load).
- Enter the spindle speed. Enter the spindle / cutter speed in RPM.
- Enter the flute count. Enter the number of teeth (flutes) on the cutter.
- Enter the known value. Enter the chip load (feed per tooth) or the feed rate, depending on the mode.
- Read the results. Read the feed rate, chip load and feed per revolution.
How it works
Chip load is the feed each cutting edge takes per revolution. The milling feed rate
is the chip load multiplied by the flute count and the spindle speed:
Vf = fz · Z · n
where fz is the chip load (feed per tooth), Z the number of
flutes and n the RPM. Rearranged, the chip load is
fz = Vf / (Z · n), and the feed per revolution is fz · Z.
Because the feed rate scales with the flute count, a cutter with more teeth feeds faster at the same chip load — each tooth still removes its own chip. Use the tool maker’s recommended chip load for the cutter diameter and material as a starting point, then tune for finish, deflection and chip evacuation.
Worked example
Verified against the live calculator
A 2-flute cutter at 5,000 RPM with a 0.0254 mm (≈ 0.001") chip load:
Vf = 0.0254 × 2 × 5000 = 254 mm/min, and the feed per revolution is
0.0254 × 2 = 0.0508 mm. Going the other way, a 254 mm/min feed on that
same cutter gives fz = 254 / (2 × 5000) = 0.0254 mm per tooth. The
calculator returns these on load.
Frequently asked questions
How do I calculate chip load?
Chip load (feed per tooth) is the feed rate divided by the flutes and spindle speed: fz = Vf / (Z · n). For example a 254 mm/min feed on a 2-flute cutter at 5,000 RPM is a chip load of 254 / (2 × 5000) = 0.0254 mm (about 0.001") per tooth.
How do I calculate feed rate from chip load?
Feed rate is chip load times flutes times RPM: Vf = fz · Z · n. A 0.0254 mm chip load on a 2-flute cutter at 5,000 RPM gives Vf = 0.0254 × 2 × 5000 = 254 mm/min.
What is chip load (feed per tooth)?
Chip load is the thickness of material each cutting edge removes per revolution — the feed advanced per tooth. It is the key parameter for milling: too small and the tool rubs and work-hardens the material; too large and the edge overloads and chips.
What is the difference between chip load and feed per revolution?
Chip load is per tooth; feed per revolution is per turn of the cutter. They differ by the flute count: feed per rev = chip load × flutes (fz · Z). A 0.0254 mm chip load on a 4-flute cutter advances 0.1016 mm per revolution.
Does the number of flutes change the feed rate?
Yes. For the same chip load and RPM, more flutes means a higher feed rate, because each tooth removes its own chip: Vf = fz · Z · n. Doubling the flutes doubles the feed rate at the same chip load.
Does this work in metric and imperial?
Yes — enter chip load and feed per tooth in mm or inches and the feed rate in mm/min or in/min. Toggle SI/Imperial in the header; 0.0254 mm is about 0.001".
Method & assumptions
- Chip load is the programmed feed per tooth — the actual chip thickness is thinner when the radial engagement is below the cutter radius (radial chip thinning), so light-radial finishing passes can run a higher programmed chip load.
- Feed rate, chip load and RPM are linked by Vf = fz · Z · n; fixing any two sets the third.
- Recommended chip loads come from the tool maker for the cutter diameter, material and operation — treat any single value as a starting point, not a limit.