Cutting at the right speed keeps tools sharp and finishes smooth. Each material has a recommended surface speed: soft aluminium can be cut very fast, stainless steel and titanium slowly. Carbide tools allow roughly three times the speed of high-speed steel.
How to use the Speeds and Feeds Calculator
- Cutting speed from
- Workpiece material
- Tool material
- Cutting speed (SFM)
- Operation
- Tool (or work) diameter
- Number of teeth / flutes
- Chip load per tooth (in)
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose preset (material and tool) or manual cutting speed, the operation, and enter the tool or work diameter, number of teeth (flutes) and chip load per tooth. Values are typical starting points – check your tool maker’s data.
Inputs explained
| Field | What to enter |
|---|---|
| Cutting speed from | Choose one: Material preset, Manual value |
| Workpiece material | Choose one: Aluminium, Brass, Bronze, Grey cast iron … |
| Tool material | Choose one: High-speed steel (HSS), Carbide |
| Cutting speed (SFM) | A number |
| Operation | Choose one: Turning / end milling, Face / slab milling, Drilling, Counterboring … |
| Tool (or work) diameter | Units: in, mm, cm, ft, m |
| Number of teeth / flutes | A number |
| Chip load per tooth (in) | A number |
What each result means
- In m/min = [Cutting speed used]×0.3048
- Spindle speed = [Cutting speed used]×12÷(pi×[Tool (or work) diameter]÷0.0254)
- Feed rate = [Spindle speed]×[Number of teeth ÷ flutes]×[Chip load per tooth (in)]
- Feed rate (metric) = [Spindle speed]×[Number of teeth ÷ flutes]×[Chip load per tooth (in)]×25.4
Example values
How the main result changes when Cutting speed changes and everything else stays at the example values above:
| Cutting speed (SFM) | Spindle speed (rpm) |
|---|---|
| 50 | 764 |
| 75 | 764 |
| 100 | 764 |
| 125 | 764 |
| 150 | 764 |
| 200 | 764 |
Formula
RPM = (SFM × 12) / (π × D in) ≈ 3.82·SFM/D · Feed (in/min) = RPM × teeth × chip load
Worked example
Inputs — Cutting speed from: Material preset; Workpiece material: Mild steel (1018); Tool material: High-speed steel (HSS); Operation: Turning / end milling; Tool (or work) diameter: 0.5 in; Number of teeth / flutes: 2; Chip load per tooth (in): 0.002.
Results — Cutting speed used = 100 SFM; In m/min = 30.5 m/min; Spindle speed = 764 rpm; Feed rate = 3.06 in/min; Feed rate (metric) = 77.6 mm/min.
Key terms
- Chip load
- Thickness of material removed by each tooth.
Frequently asked questions
What is SFM?
Surface feet per minute – the speed of the cutting edge past the material.
Why does diameter change the rpm?
Smaller tools must spin faster for the same edge speed.
What chip load should I use?
Tool makers list it by diameter and material; 0.001–0.005 in is common for small end mills.
Why is reaming slower?
Lower speed gives better hole finish and tool life.