When to use this calculator
Convert a selected metric cutting speed and diameter into spindle speed. Cutting speed must come from tool/material guidance. The result does not establish a safe machine setting.
Explore the machining feeds, speeds & time calculators for other questions in this topic. For a related calculation, use the Tap Drill Estimate Calculator: Estimate a cutting-tap pilot diameter from a metric diameter and pitch.
PUTTING IT INTO PRACTICE
Spindle Speed: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Entered cutting speed (m/min) | 100 |
| Effective cutting diameter (mm) | 20 |
| Result | 1,591.549431 rpm |
- Check the input labels and enter the example values above.
- Apply the relationship: Spindle rpm = 1000 × cutting speed/(π × diameter).
- The result is 1,591.549431 rpm, rounded for display.
How to interpret your result
Cutting speed must come from tool/material guidance. The result does not establish a safe machine setting.
Choose cutting speeds and feeds from suitable tooling and material guidance. These tools translate quantities rather than selecting safe cutting conditions. Effective diameter, engagement, machine limits and setup time need separate attention.
Frequently asked questions
Does the spindle-speed calculation recommend a cutting speed?
No. You supply the cutting speed. The tool converts it and a diameter into revolutions per minute.
When is the spindle speed calculator useful?
Convert a selected metric cutting speed and diameter into spindle speed. Cutting speed must come from tool/material guidance. The result does not establish a safe machine setting.
How do I use the spindle speed calculator?
Enter entered cutting speed (m/min), effective cutting diameter (mm). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Spindle rpm = 1000 × cutting speed/(π × diameter).
What should I check before using the result?
Cutting speed must come from tool/material guidance. The result does not establish a safe machine setting.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see Sandvik Coromant: machining formulas and definitions ↗. This is a topic reference, not an external review or endorsement of this tool.
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