Speeds and Feeds Calculator — Mill and Lathe

Pick the workpiece material and the cutter, enter the diameter, and get a starting surface speed, spindle RPM, chip load and feed rate.

These are the same starting values the Field Guide app uses, compiled from tool makers' published charts and university machining references.

Starting point — adjust for your machine, setup and the tool maker's chart.

Units

Machine

Workpiece material

Cutter material

Cutter diameter (in)

Flutes

Machine top RPM (optional)

Inch sizes can be fractions: 1/2, 3/4, 1-1/4.

688 RPM

Start here: the middle of the HSS / cobalt milling range for Low-carbon steel (1018, 1020, A36).

Surface speed: 40–140 SFM · middle 90 SFM
Spindle RPM: 306–1,070 RPM across the speed range
Chip load: 0.002–0.0038 in/tooth (HSS / cobalt end mill, 0.5" cutter)
Table feed: 5.5–10.3 IPM = 688 RPM × flutes × chip load. Start at the low end.

⚠ Sources disagree on this material (2)

Carbide end-mill SFM in plain carbon and alloy steels: Harvey's general table (e.g. 100-300 SFM for 10XX/11XX, 50-250 SFM for 4340) is 2-3x lower than Helical, SGS, Haas HTPM and Machining Doctor (about 350-675 SFM). The ranges use the higher group's lower bounds; Harvey's figures are a safe floor for light machines.

Haas HTPM chip loads (e.g. 0.0006 in at 1/4 in and 0.0019 in at 1/2 in in steel) are roughly half of the Helical, SGS and Harvey values. It may be a conservative or high-flute-count tool; it was treated as an outlier.

Confidence: high. Speeds from: Harvey Tool; Helical Solutions HEV-5 speeds & feeds sheet; Kyocera SGS Z-Carb XPR speeds & feeds; Haas Tooling HTPM end mill speeds & feeds; University of Florida MAE Design Lab; University of Pennsylvania MEAM.Design; Manufacturing Processes 4-5; Roymech; YG-1 turning inserts catalogue; Europa Tool HSS/HSSCo jobber drill cutting data; Haas Tooling general-purpose carbide drill speeds & feeds; OSG UK solid carbide drill cutting data sheet. HSS chip load: OSG, Redline Tools, Univ. of Pennsylvania.

How it's worked out

Spindle RPM = SFM × 12 ÷ (π × D), with D in inches. The old 3.82 shortcut is 12 ÷ π. Metric: RPM = Vc (m/min) × 1000 ÷ (π × D in mm).
Mill table feed = RPM × flutes × chip load per tooth.
Lathe feed rate = RPM × feed per revolution.
The answer starts at the middle of the speed range. Each range combines several makers' starting values, so start in the middle or low end on a rigid setup and adjust by sound, chips and finish.
Chip loads are listed by cutter size: carbide from the makers' end mill charts, HSS / cobalt from Redline, OSG and UPenn tables. The low end is for slotting, the high end for light side cuts. Published chip loads assume you cut at least half the cutter's width; narrower cuts make a thinner chip, so the tool can rub.
Turning feeds are insert makers' chipbreaker ranges (finish and rough).
Reduce for long reach, light machines, interrupted cuts or harder-than-nominal stock. Carbide on a manual or light machine is usually limited by rigidity and RPM, not the tool.

Starting surface speeds by material

All 30 materials in the calculator, in SFM. A dash means none of the sources publish that combination.

Starting surface speed ranges, SFM
Material	Mill, HSS	Mill, carbide	Turn, HSS	Turn, carbide
Aluminum
Aluminum, wrought (6061, 7075, 2024)	250–400	800–3000	130–400	820–2260
Aluminum, cast (A356, 380, high-silicon die-cast)	250–400	500–1400	130–400	820–2260
Copper alloys
Brass, free-cutting (C360) and leaded brasses	150–350	770–1500	175–360	575–900
Bronze (bearing/phosphor, silicon and aluminum bronze)	90–150	600–1000	90–150	575–900
Copper, pure (C101 OFE, C110 ETP)	100–500	700–1000	100–500	—
Carbon steel
Free-machining steel (12L14, 1215, 1117)	100–150	300–675	100–295	410–1250
Low-carbon steel (1018, 1020, A36)	40–140	250–675	100–260	350–1250
Medium-carbon steel (1045, 1040)	60–120	300–670	60–225	300–1080
Alloy steel
Alloy steel, annealed (4140, 4340, 4130)	60–70	350–620	60–120	360–1000
Alloy steel, prehardened ~28-32 HRC (4140 PH, 4340 HT)	20–30	250–525	30–60	360–740
Tool steel
Tool steel, annealed (A2, D2, O1, S7, H13)	40–70	160–340	40–70	195–985
Hardened steel
Hardened steel, 45-55 HRC	—	60–155	—	—
Stainless steel
Stainless steel 303 (free-machining austenitic)	40–80	200–350	40–60	260–660
Stainless steel 304 / 316 (austenitic)	20–80	200–375	20–70	260–660
Stainless steel 17-4 PH (precipitation hardening)	20–50	200–360	20–50	260–655
Cast iron
Gray cast iron (Class 30/40, GG25)	50–100	365–630	50–135	230–985
Ductile (nodular) iron (65-45-12, 80-55-06)	50–80	310–630	80–120	395–920
Titanium
Titanium 6Al-4V (Grade 5)	20–60	150–270	20–60	115–260
Nickel alloy
Inconel 718 (nickel superalloy, aged)	5–25	40–110	5–25	65–150
Plastics
Acetal / POM (Delrin homopolymer, acetal copolymer)	—	920–2000	100–245	500–1960
Nylon / PA6, PA66 (cast and extruded)	—	920–2000	100–245	500–1640
UHMW-PE (ultra-high molecular weight polyethylene)	—	920–2000	100–245	500–1640
HDPE (high-density polyethylene)	—	920–1640	100–245	500–1640
PTFE (Teflon), unfilled and filled	—	500–1640	100–245	490–1640
Acrylic / PMMA (cast and extruded)	—	200–600	100–245	200–700
Polycarbonate (Lexan, Makrolon)	—	200–2000	100–245	500–980
PVC (Type 1 rigid) / CPVC	—	—	100–245	500–700
PEEK (unfilled; glass- and carbon-filled grades)	—	500–1640	—	300–800
ABS	—	980–1640	100–245	500–1640
Composites
G-10 / FR-4 (glass-fiber epoxy laminate)	—	1670–2070	—	—

Sources

Each range is the span of the cited makers' and references' published starting values. Your tool maker's chart comes first.

Show all 31 sources