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Quick answer
FPM = π × diameter in inches × RPM ÷ 12. A 6-inch wheel rotating at 100 RPM has a rim speed of approximately 157.08 feet per minute. Diameter is required: RPM alone cannot determine linear speed.
How to use
Enter the known values, check the selected units and assumptions, then calculate. Compare the result with the worked example. Copy, print or export the table when you need a record. Measure the rotating outside diameter, not its radius. A point on the rim moves one circumference per revolution. Convert the diameter to feet and multiply by pi and RPM. Reverse mode divides the entered FPM by that circumference.
Formula and method
FPM = π × diameter(ft) × RPM; RPM = FPM / (π × diameter(ft))
Worked example
6 in × 100 RPM × π / 12 = 157.0796 ft/min
Assumptions and limits
Diameter is required; RPM alone cannot determine surface speed. The calculation assumes rigid circular motion without slip. It does not determine a safe machine speed or account for belt stretch. Observe equipment ratings separately.
Sources and methodology
Method reviewed:
Frequently asked questions
How is the result calculated?
Measure the rotating outside diameter, not its radius. A point on the rim moves one circumference per revolution. Convert the diameter to feet and multiply by pi and RPM. Reverse mode divides the entered FPM by that circumference.
What should I check before using the result?
Diameter is required; RPM alone cannot determine surface speed. The calculation assumes rigid circular motion without slip. It does not determine a safe machine speed or account for belt stretch. Observe equipment ratings separately.
Are my inputs sent to a server?
Calculations run in your browser. This plugin does not send your entered values to a server or save them. Other site analytics are governed by the site privacy policy.