Calculator guide
Calculate cutter surface speed from the tool diameter in inches and spindle speed in revolutions per minute. Results are shown in surface feet per minute (SFM) and metres per minute (m/min).
Formula or method
SFM = π × diameter (in) × RPM ÷ 12. Metric surface speed (m/min) = π × diameter (in) × 25.4 × RPM ÷ 1000.
How to use this calculator
- Enter Tool diameter in inches and Spindle speed in RPM, matching the two labelled inputs.
- Read Surface speed in SFM and Metric surface speed in m/min; the tool does not recommend a spindle speed or safe cutting conditions.
Worked example
Enter Tool diameter = 1 in and Spindle speed = 1000 RPM. Surface speed = π × 1 × 1000 ÷ 12 ≈ 261.799 SFM; metric surface speed = π × 1 × 25.4 × 1000 ÷ 1000 ≈ 79.796 m/min.
Understanding the result
The calculator converts diameter in inches and spindle speed in RPM into SFM and m/min. The formula describes surface speed only; it does not select a suitable spindle speed or establish that a cut is safe.
Limitations and assumptions
- Safe speeds depend on the material, tool, coolant, machine, and manufacturer guidance; the formula alone does not choose a safe speed.
- The worked example demonstrates the stated assumptions, not a recommendation about your personal circumstances.
Frequently asked questions
Which inputs should I check first?
For Machining Surface Speed Calculator, check Tool diameter (in) and Spindle speed (RPM). Compare both Surface speed (SFM) and Metric surface speed (m/min); do not enter a millimetre value directly in the inch field.
Why might my result differ from another tool?
Compare the other tool’s machining surface speed calculator method, input units, rounding and assumptions. A matching title does not guarantee that both tools answer the same question.
Does a linked reference certify this result?
No. Sandvik Coromant provides machining formula background, but it does not endorse this website or certify that a selected surface speed is suitable or safe for your setup.
Sources
Educational and planning information only. Sources are attributed background or formula references, not endorsements. Verify consequential decisions with an appropriate qualified professional.