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, tool coating, tool reach, 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 — use shallow passes, strong dust extraction, and air blast if available. Avoid breathing dust. |
| G-10 | Tough glass laminate — use shallow passes, air blast, and dust extraction. Tool wear can be high. |
| Rogers / PTFE | Soft core material — use sharp tools, light cuts, and air blast. Reduce feed if smearing occurs. |
| Carbon Fiber | Very abrasive material — use vacuum extraction, air blast if available, and lighter feed to reduce fraying and tool wear. |
| Aluminum | Prevent chip welding — use strong chip clearing, air blast, mist coolant, or suitable cutting lubricant when appropriate. |
| Mild Steel / Low Carbon Steel | Use coated carbide when possible. Coolant, mist, or air blast can help manage heat and chip evacuation. |
| Alloy Steel | Use coated carbide, rigid toolholding, conservative depth of cut, and coolant, mist, or air blast when appropriate. |
| Stainless Steel | Avoid rubbing and work hardening. Use a rigid setup, steady feed, and coolant, mist, or air blast to help control heat and chips. |
| Tool Steel / Hardened Steel | Use coated carbide, shallow cuts, rigid toolholding, and good chip evacuation. Air blast is often helpful; use coolant only when appropriate. |
| Cast Iron | Abrasive and dusty. Use chip/dust control, air blast, or vacuum extraction. Coolant is often avoided unless your setup is designed for it. |
| MDF | Engineered wood — use dust extraction and avoid heat buildup. Reduce feed or RPM if burning occurs. |
| Softwood | Use dust extraction. A steady feed helps avoid burning and rubbing. |
| Hardwood | Use dust extraction. Reduce feed if chatter, burning, or chipping occurs. |
| Plastic / Acrylic | Avoid melting. Use sharp tools, steady feed, and air blast if available to help clear chips and reduce heat. |
| Ice | Use low RPM, light cuts, and gentle chip clearing to 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, rubbing, work hardening, or premature tool wear.