# CNC Router Speeds and Feeds Calculator

CNC router speeds and feeds calculator. Returns spindle RPM, feed rate in IPM and mm/min, and chip load for hardwood, softwood, plywood, MDF, plastic, foam, and aluminum. Tuned for Shapeoko, Onefinity, X-Carve, ShopBot.

## What this calculates

A CNC router speeds and feeds calculator turns bit diameter and material into spindle RPM and feed rate, the two numbers a Shapeoko, Onefinity, X-Carve, ShopBot, or Avid CNC control actually programs. This calculator handles hardwood, softwood, plywood, MDF, plastic, acrylic, foam, and aluminum on a router; it uses the same SFM and chip load equations that Onsrud Cutter, Amana Tool, and Whiteside publish in their router bit data sheets. Output is capped at your router's max RPM so you get a number you can actually run.

## Inputs

- **Router Bit Diameter** (in) — min 0.001 — Router bit or end mill diameter. Common router sizes 1/8, 1/4, 3/8, 1/2 inch.
- **Material** — options: Hardwood (oak, maple, walnut), Softwood (pine, cedar, fir), Plywood (Baltic birch, cabinet), MDF (medium-density fiberboard), OSB (oriented strand board), Particleboard / melamine, Plastic (Delrin, HDPE, PVC), Acrylic (cast, extruded), Foam (polyurethane, EPS), Aluminum (6061, 7075) — Pick the stock material. SFM and chip load lookups are tuned for router use.
- **Bit Material** — options: HSS, Carbide (solid or insert) — Carbide is standard on CNC routers. HSS is rare and runs 40-50 percent slower.
- **Flutes** — min 1, max 6 — Router bit flute count. 1 flute for soft wood and aluminum, 2 for hardwood and plywood, 3-4 for finishing.
- **Chip Load Override (IPT)** (in/tooth) — min 0 — Optional. Enter a specific chip load from an Onsrud, Amana, or Whiteside data sheet to override.
- **Router Max RPM** (RPM) — min 0 — Maximum spindle speed. Makita RT0701 30000, Dewalt 611 27000, Bosch 1617 25000, typical spindle 24000.

## Outputs

- **Spindle RPM** (RPM) — Calculated spindle RPM from SFM.
- **Capped RPM** (RPM) — RPM capped at router max. Use this value on the control panel.
- **Feed Rate** (IPM) — Linear feed rate in inches per minute.
- **Feed Rate** (mm/min) — Feed rate in mm/min for metric CNC router controls.
- **Chip Load** (IPT) — Chip load per tooth used in the feed equation.
- **Surface Speed** (SFM) — Surface feet per minute at the bit edge.

## Details

CNC router speeds and feeds formulas

The formulas are the same as for milling; the difference is material SFM and chip load values.

  - Spindle RPM = (SFM x 12) / (pi x D) where D is the bit diameter in inches.

  - Feed rate (IPM) = RPM x chip load per tooth x flute count.

  - mm/min = IPM x 25.4.

Example: 1/4 inch 2 flute compression bit in hardwood at 2,200 SFM, 0.008 IPT baseline. Formula RPM = (2200 x 12) / (pi x 0.25) = 33,614 RPM. Most routers cap at 18,000-24,000 RPM; at 18,000 RPM and 0.008 IPT with 2 flutes, feed = 18,000 x 0.008 x 2 = 288 IPM (7,315 mm/min). That is a realistic CNC router speeds and feeds calculator output for a 1/4 inch bit cutting oak or maple.

CNC router speeds and feeds chart

  
    MaterialCarbide SFMChip load (IPT)Typical feed (1/4" bit, 18k RPM, 2 flutes)
  
  
    Hardwood (oak, maple, walnut)22000.008288 IPM
    Softwood (pine, cedar)28000.012432 IPM
    Plywood (Baltic birch)23000.009324 IPM
    MDF25000.010360 IPM
    OSB22000.010360 IPM
    Particleboard / melamine24000.011396 IPM
    Acrylic (cast)24000.006216 IPM
    Plastic (Delrin, HDPE)20000.005180 IPM
    Foam (polyurethane)30000.015540 IPM
    Aluminum 606115000.004144 IPM
  

CNC router speeds and feeds calculator for Shapeoko, Onefinity, X-Carve

Hobby routers have three constraints that a shop VMC does not: spindle torque is limited, machine rigidity is limited, and dust collection is usually non-optional. Plug your router max RPM into this CNC router speeds and feeds calculator (18,000 for most trim routers, 24,000 for HF spindles, 27,000 for Dewalt 611, 30,000 for Makita RT0701) and the calculator caps the output. For a Shapeoko or X-Carve with a Dewalt 611 at 16,500 RPM (dial 1), a 1/4 inch carbide bit in hardwood wants 132 IPM; at dial 6 (27,000 RPM) it wants 216 IPM. A Shapeoko XL or Pro that is rigid enough can push those numbers; a stock X-Carve might bog past 100 IPM.

Chip load and bit life

CNC router chip load is the feed per flute per revolution. Too low (below 0.003 IPT on a 1/4 inch router bit) and the bit rubs instead of cutting, which generates heat, glazes the bit, and burns the wood. Too high (above 0.015 IPT on a 1/4 inch in hardwood) and the bit chatters, chips, or breaks. The CNC router speeds and feeds chart above hits the middle of each range. For a new bit, start at the chart value; if chips come out as dust, bump feed 10 percent; if the router bogs, drop feed 10 percent.

Compression, upcut, downcut, straight

Bit geometry changes the optimum chip load. Compression bits (upcut at tip, downcut at shank) handle plywood and veneered panels best at 0.006-0.010 IPT. Upcut spirals cut the fastest in solid wood at 0.008-0.012 IPT but tear the top face. Downcut spirals leave a clean top face but trap chips; run 0.005-0.008 IPT and ramp cautiously. Straight flutes are rare on modern CNC routers; use spirals unless working very thin stock. This CNC router speeds and feeds calculator uses a balanced chip load that works for any bit style at the chart SFM.

Spindle vs trim router

A variable-frequency spindle (Mechatron, HSD, 2.2 kW Chinese) holds rated RPM under load. A trim router (Makita RT0701, Dewalt 611) drops RPM 20-30 percent under heavy cut. If you run a trim router, aim for the lower chip load and accept slower feed, or upgrade to a spindle for serious work. The CNC router speeds and feeds calculator numbers assume rated RPM at the bit; the cap feature lets you enter the real value.

## Frequently Asked Questions

**Q: How do I calculate CNC router speeds and feeds?**

A: Spindle RPM = (SFM x 12) / (pi x bit diameter in inches). Feed rate (IPM) = RPM x chip load per tooth x flutes. A 1/4 inch 2 flute carbide bit in hardwood (2,200 SFM, 0.008 IPT) wants 33,614 RPM and 288 IPM at that RPM. Most routers cap at 18,000-24,000 RPM, so feed scales down with the cap. This CNC router speeds and feeds calculator does both steps and applies the cap.

**Q: What chip load should I use on a CNC router?**

A: Hardwood 0.008 IPT, softwood 0.012 IPT, plywood 0.009 IPT, MDF 0.010 IPT, acrylic 0.006 IPT, HDPE 0.005 IPT. These are midpoints of the Onsrud, Amana, and Whiteside published router bit chip load charts. Small bits (under 1/8 inch) need 50 percent of these values; big bits (over 3/4 inch) can run 125 percent. The CNC router speeds and feeds calculator scales chip load automatically.

**Q: Will this work for my Shapeoko, Onefinity, or X-Carve?**

A: Yes. Enter your router max RPM (Makita RT0701 30,000, Dewalt 611 27,000, Bosch 1617 25,000) and the calculator caps the output. A Shapeoko Pro or Onefinity is rigid enough to run the chart feed; an older X-Carve with wheels may need to back off 30 percent. Start at 80 percent of calculated feed, then dial up based on chip size and router sound.

**Q: What RPM for 1/4 inch end mill on CNC router in oak?**

A: Oak is a hardwood, so the chart SFM is 2,200. RPM = (2,200 x 12) / (pi x 0.25) = 33,614 RPM. Most routers cap below that; run at the router max (typically 18,000-24,000 RPM) and accept the slightly lower SFM. Feed at 18,000 RPM with 0.008 IPT and 2 flutes is 288 IPM (7,315 mm/min). This CNC router speeds and feeds calculator returns both the ideal and the capped RPM.

**Q: Can a CNC router cut aluminum?**

A: Yes, with a carbide upcut or single-flute bit, 0.004 IPT, 1,500 SFM, mist or air-blast cooling, and a rigid machine. A 1/4 inch single-flute at 18,000 RPM wants 72 IPM in aluminum. Depth of cut under 0.030 inches per pass. Shapeoko Pro and Onefinity Journeyman can do this reliably; stock X-Carve or 3018 CNCs cannot. This CNC router speeds and feeds calculator includes aluminum in its material list.

**Q: Why cap the RPM in the calculator?**

A: The SFM equation does not know your router's spindle limit. Small bits in wood often want 30,000-50,000 RPM, which no trim router or hobby spindle can deliver. The cap forces the calculator to use the max RPM you enter, then computes feed rate at that real RPM. Without the cap, the feed rate would be impossible to achieve on your machine.

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Source: https://vastcalc.com/calculators/physics/cnc-router-speeds-and-feeds
Category: Physics
Last updated: 2026-04-08