Feed Rate Calculator
How fast to push the cutter — table feed from chip load, tooth count and spindle speed, with the metal removal it buys.
Feed Rate Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Plain-engagement chip load — no thinning correction
- Rigid-setup feeds; chatter halves them in practice
In short: A four-flute cutter at 1,500 rpm taking a tenth of a millimetre per tooth moves the table 600 mm a minute — and at a 4 by 2 mm bite that removes 4.8 cubic centimetres of steel every minute. Chip load is the contract: feed too light and the edge rubs instead of cutting, work-hardening the surface; feed too heavy and the flute chokes. The table speed is just teeth times chip load times rpm.
Formula
vf = rpm × fz × z — MRR = ae × ap × vf
Every revolution hands each tooth its chip load, so the table must advance rpm times the load times the tooth count to keep the bite honest. Multiply the moving slice — width times depth times table speed — and the removal rate falls out in cubic millimetres a minute. These are starting feeds for a rigid setup; a chatter or a lean cutter halves them before the tool catalog does.
Worked Example
- Read the chip load the cutter can take.
- Multiply by teeth and rpm for the table feed.
- Width times depth times feed prices the removal.
Defaults: 1,500 rpm, 0.1 mm chip load, 4 teeth — 600 mm/min at the table, 4.8 cm³/min of removal at the 4 by 2 mm bite. A two-flute at the same chip load drops the table to 300 and the removal to 2.4.
Strengths & Limits Of This Model
Where this engine is strong
- Per-tooth thinking built in
- Removal rate prices the cycle before it runs
Where it stops
- Vendor chip-load charts still govern the final cut
Practical Use Cases
Milling slots
feed for the curl, not the dust
Cycle estimates
removal rate sets the clock
Spindle loading
chip thinning starts here
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Feed Rate Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
Why does chip load matter more than feed speed?
The edge cuts, the table just carries it. Two setups at the same table speed can feed the edge wildly differently once tooth count and rpm change — chip load is the number the flute actually feels, which is why the chart is written per tooth.
What happens if I feed too light?
The edge rubs instead of biting, and a rubbing carbide edge work-hardens steel exactly where the next pass has to cut. If the cutter squeals and the dust shines, double the feed before you blame the tool.
And too heavy?
The flute chokes on its own chip, thrust climbs and something moves — the part, the cutter or the tooth. Halve the load, take a second pass, and the cycle time usually still wins.
Does a two-flute feed half of a four-flute?
At the same chip load and rpm, yes — half the teeth, half the entries per revolution. That is why aluminum cutters run two flutes at higher rpm to catch up: the product of teeth and speed is what sets the table.
What is chip thinning?
When the radial width of cut drops below the chip load, the tooth's actual slice is thinner than the feed number suggests, so the feed can be raised to keep the edge working. This screen quotes the plain engagement number; the thinning correction lives in the tool vendor's tables.
How do I turn removal into a cycle time?
Divide the stock volume by the removal rate. A pocket of 48 cm³ at 4.8 cm³/min is ten minutes of full-engagement cutting — before approaches, retracts and the passes you feather in.
Metric and inch chip loads?
One thousandth of an inch is 0.0254 mm, so a 0.004-inch load and a 0.1 mm load are the same cut within chart noise. Keep one system per setup; mixing them is how tables get run twice as fast as the cutter wanted.
Where does the spindle speed come from?
From the material and the cutter diameter — the machining-speed page derives it from a cutting speed, and the drill-speed page does the same for a bit. This page takes it as given and prices the table move.