Milling Depth Of Cut Calculator

Work out milling depth of cut instantly with clear inputs, formula shown and shareable results.

About Milling Depth Of Cut Calculator

Depth of cut is usually limited by spindle power rather than tool strength. Rearranging the removal rate relation, the deepest cut the machine can drive is available power divided by unit power, width and feed. Working at 80 percent of that leaves headroom for a hard spot or a dull edge.

Formula

Power limited depth

Depth = (hp / unit power) / (width x feed)

Worked example

With the default values below, Milling Depth Of Cut Calculator returns Maximum depth of cut of 0.4167. Change any input above and every figure here is recalculated in your browser.

Inputs used

Available spindle powerminimum 0.1 hp: 5 hp
Width of cutminimum 0.01 in: 1 in
Feed rateminimum 0.01 in/min: 12 in/min
Unit power for materialminimum 0.05 hp per in³/min: 1 hp per in³/min

Results

Maximum depth of cut: 0.4167 in
Recommended working depth: 0.3333 in
Removal rate at maximum depth: 5.000 in³/min
Spindle power consumed: 5.00 hp

Step by step

1Values used
2Power limited depth
3Maximum depth of cut= 0.4167 in
4Recommended working depth= 0.3333 in
5Removal rate at maximum depth= 5.000 in³/min
6Spindle power consumed= 5.00 hp

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Milling Depth Of Cut figure worked out?

Depth = (hp / unit power) / (width x feed). Depth of cut is usually limited by spindle power rather than tool strength.

Is rigidity ever the real limit?

Often. On long thin tools or light machines, chatter sets in well below the power limit, and the practical depth is set by the ratio of tool length to diameter instead.

What values do I need to enter?

This calculator takes 4 inputs: Available spindle power, Width of cut, Feed rate, Unit power for material. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.