Feed Rate Calculator
This feed rate calculator finds the table feed for milling or the feed for turning and drilling from the spindle speed, the number of flutes, and the chip load. Enter a width and depth of cut and the feed rate calculator also returns the material removal rate, in inch or metric units, so you can program a CNC or set a manual mill with confidence.
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The Feed Rate Calculator is part of our Machinery collection. Browse more machinery to size, convert, and check your work alongside this tool.
What the feed rate calculator does
Feed rate is how fast the tool moves through the material. In milling, every flute takes a chip on each turn, so the feed equals the spindle speed times the number of flutes times the chip load, the thickness each flute cuts. In turning and drilling, the tool advances a set distance per revolution. The feed rate calculator handles both, and it adds the material removal rate for milling when you give the width and depth of cut.
Feed rate formula
For milling, multiply speed, flutes, and chip load; for turning, multiply speed and feed per revolution:
The same formulas work in millimeters; the removal rate is shown in cm³/min for metric input.
Feed rate calculator example
A 4 flute end mill at 5,000 RPM with a chip load of 0.002 in per tooth, cutting 0.25 in wide and 0.5 in deep:
In metric, a 3 flute cutter at 8,000 RPM and 0.05 mm per tooth feeds at 1,200 mm/min. A lathe at 1,200 RPM with 0.008 in/rev feeds at 9.6 in/min.
How to use the feed rate calculator
Choose milling or turning and drilling, pick inch or metric units, then enter the spindle speed in RPM. For milling, enter the number of flutes and the chip load per tooth; for turning or drilling, enter the feed per revolution in the chip load field. Add the radial width and axial depth of cut to see the material removal rate. Press Calculate to read the feed in inches or millimeters per minute.
Reading the milling feed rate
The feed rate is what you program as F in a CNC program or set on the power feed. The feed per revolution tells you how far the tool moves each turn. If the cut squeals or rubs, the chip load is usually too light; if the tool deflects or chatters, it may be too heavy or the depth too large. The material removal rate lets you compare strategies: a light, fast cut and a heavy, slow cut can remove the same volume per minute with very different tool loads.
When to use a CNC feed rate calculator
- Programming feeds for a new end mill or insert
- Converting a tool maker chip load into IPM
- Checking whether a machine can reach the feed you need
- Comparing roughing strategies by removal rate
- Setting lathe feeds for finishing passes
Common feed rate calculator mistakes
- Mixing units. Keep RPM, chip load, and cut sizes in one unit system.
- Using feed per rev as chip load. For milling, enter the chip load per tooth.
- Forgetting flutes. A 2 flute cutter feeds at half the rate of a 4 flute at the same chip load.
- Ignoring chip thinning. Light radial cuts need a higher feed to keep the chip load.
Tips for setting feed rate and chip load
- Start at the middle of the tool maker chip load range.
- Listen for a steady cut and look for even, curled chips.
- Reduce depth before chip load if the machine lacks power.
Feeds and speeds: chip load first
Good machining starts from two numbers the tool maker publishes: a cutting speed for the material and a chip load for the tool diameter. Cutting speed sets the RPM, chip load sets the feed. Run a carbide end mill too slow on feed and each edge rubs instead of cutting, which work hardens stainless steel and wears the edge fast. Run it too heavy and the edge chips or the cutter breaks. Small cutters need lighter chip loads because they flex; a 1/8 in end mill may run at a quarter of the chip load of a 1/2 in cutter in the same steel. When you cut a slot or a wide pocket, the full chip load applies. When the width of cut is small, chip thinning reduces the real chip thickness, so CAM systems raise the programmed feed to keep the edge loaded. Use the surface speed calculator to pick RPM, then this feed rate calculator to set the feed.
Material removal rate and spindle power
Removal rate links the cut to the machine. Each material needs a certain power per unit volume removed per minute, roughly 1 hp per cubic inch per minute in mild steel and about a third of that in aluminum, though tool sharpness and rake change the figure. A cut of 5 in³/min in steel therefore needs around 5 hp at the spindle, before losses. If the machine stalls or the spindle load meter runs high, cut the depth or width before you cut the chip load, because chip load protects the tool edge. Check spindle power and torque at your RPM with the horsepower calculator, since many spindles lose power at low speed.
Feed rate chart for a 4 flute end mill
Feed rate in inches per minute at common speeds and chip loads, from RPM × 4 × chip load:
| RPM | 0.001 in/tooth | 0.002 in/tooth | 0.003 in/tooth | 0.004 in/tooth |
|---|---|---|---|---|
| 2,000 | 8.0 | 16.0 | 24.0 | 32.0 |
| 5,000 | 20.0 | 40.0 | 60.0 | 80.0 |
| 10,000 | 40.0 | 80.0 | 120.0 | 160.0 |
Feed Rate Calculator FAQ
How do you calculate feed rate?
For milling, multiply RPM by the number of flutes and the chip load per tooth. 5,000 RPM, 4 flutes, and 0.002 in per tooth give 40 inches per minute.
What is chip load?
Chip load, or feed per tooth, is the thickness of material each cutting edge removes per revolution. Tool makers list a recommended range for each material and tool diameter.
How do I find RPM for the feed rate formula?
RPM equals the cutting speed in SFM times 3.82 divided by the tool diameter in inches. The surface speed calculator does the conversion in metric.
What is material removal rate?
It is the volume of material removed per minute: width of cut times depth of cut times feed rate.