Carbide End Mill Feed & Speed Calculator
Use this calculator as a starting point for carbide end mill feeds and speeds. End mill settings vary by material, tool diameter, flute count, spindle speed, machine rigidity, chip evacuation, and desired finish.
Enter the cutting diameter in decimal inches. Example: enter 0.125 for a 1/8" end mill.
Enter the highest RPM your spindle or router can realistically run. The calculator estimates a material-based RPM, then uses the lower of that value or your machine’s maximum RPM.
How the Calculation Works
The calculator estimates a spindle RPM from the selected material and tool diameter, then limits that RPM to your machine’s maximum RPM. Chip load is also adjusted by tool diameter so very small end mills receive a lighter starting feed.
Feed Rate (IPM) = Adjusted Chip Load × Number of Flutes × RPM Used
Example: if the adjusted chip load is 0.00028", the tool has 2 flutes, and the spindle RPM used is 6,100:
Material Notes
| Material | Starting Note |
|---|---|
| FR-4 | PCB laminate — shallow passes; use dust extraction. |
| G-10 | Tough glass laminate — higher wear; use air blast for debris. |
| Rogers / PTFE | Soft core — reduce feed; watch for smearing if chip load is high. |
| Carbon Fiber | Very abrasive — lighter feed; vacuum extraction recommended. |
| Aluminum | Prevent chip welding; use good chip clearing and appropriate lubrication if needed. |
| MDF | Engineered wood — moderate feed; watch for heat buildup. |
| Softwood | Light wood — slightly higher feed helps avoid burning. |
| Hardwood | Denser wood — reduce feed if chatter or chipping occurs. |
| Plastic / Acrylic | Avoid melting; moderate RPM and steady feed are important. |
| Ice | Low RPM and light cuts help prevent cracking and melting. |
These calculator values are starting points only. Reduce feed rate, depth of cut, or spindle load if you see excessive heat, chatter, poor finish, tool deflection, chip packing, or premature tool wear.