Feeds And Speeds Calculator
Calculate optimal spindle speed (RPM) and feed rate (IPM) for milling operations based on tool diameter, material, and number of flutes.
Published by:
isCalculator Editorial Team
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How to Use the Feeds and Speeds Calculator
This calculator works in imperial units (inches, SFM, IPM). Follow these steps:
- Enter Tool Diameter – Input the cutter diameter in inches (e.g., 0.5 for ½").
- Select Cutting Speed – Choose a material from the dropdown (SFM values pre-filled).
- Enter Number of Flutes – How many cutting edges the tool has (1–6).
- Select Chipload – Choose chip load per tooth (IPT) based on finish: Fine (0.001), General (0.003), or Roughing (0.005).
- Click "Calculate" – Results show Spindle Speed (RPM) and Feed Rate (IPM).
Formulas used: RPM = (Cutting Speed × 3.82) ÷ Tool Diameter; Feed = RPM × Flutes × Chipload.
Previous Results
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Frequently Asked Questions
Surface Feet per Minute (SFM) is the linear speed of the cutting tool relative to the workpiece. It depends on the material being cut.
Inches per Tooth (IPT) is the amount of material removed by each cutting edge per revolution. It affects surface finish and tool life.
RPM = (Cutting Speed (SFM) * 3.82) / Tool Diameter (inches). The constant 3.82 converts SFM to RPM.