How do I calculate feed rate for milling?

F = fz × z × n — feed per tooth times the number of teeth times spindle speed. A 4-flute cutter at 0.004 in per tooth and 2,000 RPM gives 32 in/min, or about 813 mm/min.

Does feed rate change with depth of cut?

No. Feed rate is set by the chip load per tooth and the spindle speed. Depth and width of cut change the material removal rate and the cutting force, but reducing the feed on a heavy cut causes rubbing rather than helping.

What is chip thinning?

When the radial width of cut is less than half the cutter diameter, the actual chip is thinner than the programmed feed per tooth suggests. Increasing the feed to compensate keeps the chip load at the intended value and prevents the tool from rubbing.

How do I convert feed rate to mm/min?

Multiply by 25.4. A feed of 32 in/min is 813 mm/min. In metric practice the feed per tooth is given in mm and the arithmetic is the same.

Why does the calculator have a fixed chip thinning output?

Because chip thinning depends on the radial engagement and the cutter diameter, which are entered separately. The field is shown as a reminder that the programmed feed may need raising when the radial engagement is small — take the correction factor from your tooling catalogue.

Milling Feed Rate Calculator

Compute the table feed rate for milling from feed per tooth, number of teeth and spindle speed, with the chip load and material removal rate.

Data verified 2026-09-29 · based on n/a — standard engineering relationships, no single governing revision

Quick Answer

Table feed is F = fz · z · n — feed per tooth × number of teeth × RPM. Note that feed rate is independent of depth and width of cut; those change the material removal rate and the load on the tool, not the feed.

Milling Feed Rate

Feed per tooth, fz (in)

Number of teeth, z

Spindle speed (RPM)

Depth of cut (in)

Width of cut (in)

The Formulas Used

Table feed: F = fz · z · n where fz = feed per tooth, z = number of teeth, n = spindle speed
Material removal rate: MRR = ap · ae · F
Feed per revolution: fr = fz · z

Feed Rate Is Independent of Depth of Cut

The table feed depends only on chip load per tooth and spindle speed. Depth and width of cut change how much material is removed per minute and how much force the tool sees, but they do not change the feed — that is set by the chip the tooth has to take.

This trips people up because it feels wrong: surely a heavier cut should be fed slower? It should not, and feeding slower on a heavy cut is what causes rubbing, work hardening and short tool life. If a heavy cut overloads the tool, reduce the speed or the depth, not the feed per tooth.

Frequently Asked Questions

How do I calculate feed rate for milling?: F = fz × z × n — feed per tooth times the number of teeth times spindle speed. A 4-flute cutter at 0.004 in per tooth and 2,000 RPM gives 32 in/min, or about 813 mm/min.
Does feed rate change with depth of cut?: No. Feed rate is set by the chip load per tooth and the spindle speed. Depth and width of cut change the material removal rate and the cutting force, but reducing the feed on a heavy cut causes rubbing rather than helping.
What is chip thinning?: When the radial width of cut is less than half the cutter diameter, the actual chip is thinner than the programmed feed per tooth suggests. Increasing the feed to compensate keeps the chip load at the intended value and prevents the tool from rubbing.
How do I convert feed rate to mm/min?: Multiply by 25.4. A feed of 32 in/min is 813 mm/min. In metric practice the feed per tooth is given in mm and the arithmetic is the same.
Why does the calculator have a fixed chip thinning output?: Because chip thinning depends on the radial engagement and the cutter diameter, which are entered separately. The field is shown as a reminder that the programmed feed may need raising when the radial engagement is small — take the correction factor from your tooling catalogue.

Value Sources

Each data column on this page is tied to the source it came from. The numbers in square brackets correspond to the table headers above.

#	Source	Type	Revision / method
[1]	ASME B1.1 — Unified Inch Screw Threads	standard	ASME B1.1-2019 — source
[2]	ASTM A615 — Deformed steel bars for concrete reinforcement	standard	ASTM A615/A615M-20 — source
[3]	ASTM E140 — Hardness Conversion Tables	standard	ASTM E140-12b — source
[4]	Values computed in your browser	derived	Evaluated locally from the formulas shown on the page. No data leaves the device.
[5]	ISO 4287 — Surface texture: Profile method	standard	ISO 4287:1997 — source
[6]	ISO 68-1 — Basic profile	standard	ISO 68-1:2023 — source
[7]	NFPA 70 NEC Table 310.16	standard	NEC 2023 (NFPA 70-2023) — source

Data Sources

Standard	Revision	What it covers on this page
Formulas as shown on this page	n/a — standard engineering relationships, no single governing revision	every value this calculator produces

Cross-checked against:

Formulas verified against the corresponding reference chart on this site, so the calculator and the published tables agree

Derived values — the following values on this page are calculated, not taken directly from the standard:

Value	How it is derived
All outputs	Computed in the browser from the formulas above. No data leaves the device.

Outputs are computed from the formulas shown. Verify against the governing standard for design or acceptance work.

Accuracy and use. The values on this page are compiled from the published standards and cross-checked sources listed above. Where values are derived, the derivation is stated. No warranty, express or implied, is made as to the accuracy or completeness of this information, and no liability is accepted for any loss or damage arising from its use. Engineering reference data is provided for guidance in preliminary work — before a value is used for design, fabrication or acceptance testing, verify it against the current revision of the governing standard and against your own inspection. The user assumes all risk and responsibility in connection with the use of this information.

Cite This Page

Every value on this page is traceable to the sources listed above. If you use the data in a document, paper or report, cite it as:

Plain text

Engineering Reference. "Milling Feed Rate Calculator." https://refmanual.com/calculators/mill-feed-rate/ (accessed 2026-09-29). Data from Formulas as shown on this page, n/a — standard engineering relationships, no single governing revision.

BibTeX

@misc{mill-feed-rate,
  title        = {Milling Feed Rate Calculator},
  author       = {{Engineering Reference}},
  howpublished = {\url{https://refmanual.com/calculators/mill-feed-rate/}},
  note         = {Accessed: 2026-09-29},
  source       = {Formulas as shown on this page, n/a — standard engineering relationships, no single governing revision}
}

RIS (EndNote, Zotero, Mendeley)

TY  - ELEC
TI  - Milling Feed Rate Calculator
AU  - Engineering Reference
PB  - Engineering Reference
UR  - https://refmanual.com/calculators/mill-feed-rate/
PY  - 2026
DA  - 2026-09-29
N1  - Source: Formulas as shown on this page, n/a — standard engineering relationships, no single governing revision
ER  -

Each row in the tables above also has a permanent link — hover a row and use the # link to cite a single value rather than the whole page.