Sfm Calculator
Calculate the surface feet per minute (SFM) for machining operations based on workpiece diameter and spindle speed.
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isCalculator Editorial Team
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How to use this tool?
How to Use the SFM Calculator
- Enter the Diameter – Input the tool or workpiece diameter in inches (e.g., 0.5).
- Enter the Spindle Speed – Input the RPM (e.g., 1000).
- Click "Calculate SFM" – The result shows Surface Feet per Minute (SFM).
- Read the Result – The SFM value appears in green, along with the formula used.
Important: Both inputs must be positive numbers. The calculator uses the imperial system (inches). If you change any input, the result will hide until you recalculate.
Previous Results
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Frequently Asked Questions
SFM stands for Surface Feet per Minute, a measure of cutting speed in machining.
SFM = (π × Diameter × RPM) / 12, where diameter is in inches.
SFM helps determine optimal spindle speed for tool life and surface finish.