Cutting Parameters
Optimal Spindle Speed
The recommended speed at which the router/spindle should rotate. Measured in RPM (Revolutions Per Minute). Higher RPMs generally work better for smaller bits and harder materials.
0 RPM
Chipload
The thickness of material each cutting flute removes per revolution. This is the key parameter that determines bit life and cut quality. Too low = rubbing/burning, too high = breaking/chatter.
0
Feed Rate (in/min)
How fast the bit moves through the material. Calculated as: RPM × Chipload × Number of Flutes. This determines how quickly your job completes and affects cut quality.
0
Stepdown (in)
Depth of cut per pass (also called DOC - Depth of Cut). Shallower stepdowns are safer but slower. Deeper stepdowns remove more material but increase tool load.
0
Stepover (in)
The distance between adjacent cutting passes (also called WOC - Width of Cut). Smaller stepover = smoother finish but longer machining time. Typically a percentage of bit diameter.
0
Surface Speed (SFM)
The speed at the cutting edge of the bit. Measured in SFM (Surface Feet per Minute) or m/min. Higher surface speeds can improve finish but may reduce tool life. Calculated as: (π × Diameter × RPM) ÷ 12
0
Plunge Rate (in/min)
How fast the bit should plunge straight down into the material. Typically 50% of the feed rate for safety. Use slower plunge rates for harder materials.
0
Material Removal Rate (in³/min)
Volume of material removed per minute. Higher MRR = faster machining but more stress on machine and bit. Calculated as: Feed Rate × Stepdown × Stepover
0
Router Dial Setting
Closest Dial Setting
N/A
End Mill Selection Guide
Upcut Bits
Flutes spiral upwards. They pull chips up and out of the cut.
Use for:
• Fast material removal (roughing).
• Cutting plastics (helps prevent melting).
• When chip evacuation is critical.
Result: Clean bottom edge, but may cause splintering on the top surface of woods.
Downcut Bits
Flutes spiral downwards. They push chips down into the cut.
Use for:
• Laminated materials and veneers.
• When a clean, sharp top surface is essential.
• Shallow cuts and finishing passes.
Result: Clean top edge, but may cause a rougher bottom edge. Poor chip evacuation.
Compression Bits
A hybrid design with upcut flutes at the tip and downcut flutes at the shank.
Use for:
• Plywood, MDF, and composites.
• Cutting materials where both top and bottom surface quality matters.
• Must be used for through-cuts.
Result: Clean top and bottom edges simultaneously.
Help Improve This Tool
This calculator is powered by a public Google Sheet. The community-driven data is what makes this tool useful. You can view the sheet to see how the calculations are sourced.
Have a suggestion for a new material, bit, or have updated parameters that work well for you? Please use the contact form to send in your additions. Please provide the data in the same format as the columns in the sheet so it can be easily added to the database for everyone's benefit.