Physics

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Centrifuge Speed Calculator.

Convert relative centrifugal force and rotor radius to revolutions per minute.

On-device calculationNo signup
01

Set your values

Results update as you type.

rpm: 2,990.743023 rpm

rpm

0.000000rpm
revolutionsPerSecond: 49.845717 Hz

revolutionsPerSecond

0.000000Hz

Results update automatically as you type.

This page applies only the stated idealized equation and explicit inputs; verify specialized engineering, medical, or safety decisions against applicable standards.

Use Cases

Protocol replication

When following a protocol that specifies RCF, use this calculator to determine the RPM setting for your specific rotor.

Example: If a protocol requires 10,000 ×g and your rotor radius is 8 cm, the calculator gives you the RPM.

Equipment compatibility

Check if your centrifuge can achieve the required RCF by converting the desired RCF to RPM and comparing with the centrifuge's maximum speed.

Example: For a rotor radius of 10 cm, 20,000 ×g converts to about 13,000 RPM.

Frequently Asked Questions

What is the formula used to convert RCF and rotor radius to RPM?
The calculator uses the standard formula: RPM = sqrt(RCF / (1.118 × 10^-5 × rotor radius in cm)). This converts the relative centrifugal force (in ×g) and rotor radius (in cm) to revolutions per minute.
Why is rotor radius important in centrifuge speed conversion?
Rotor radius determines the distance from the center of rotation to the sample. The same RPM produces different RCF depending on the radius, so accurate radius input is essential for correct conversion.
Can I use this calculator for any centrifuge rotor?
Yes, as long as you know the rotor radius in centimeters and the desired RCF in ×g. The calculator works for any rotor, but ensure you use the correct radius for your specific rotor and bucket.

Tips & Common Mistakes

Tips

  • Measure the rotor radius accurately: it's the distance from the center of the rotor to the sample position when the rotor is spinning.
  • Use the same units as the calculator: RCF in ×g and radius in cm. If your radius is in mm, convert to cm first.
  • Double-check your RCF value: some protocols specify RCF at the bottom of the tube, which may differ from the average radius.
  • Remember that RPM is not directly comparable across different rotors; always use RCF for consistency.

Common Mistakes to Avoid

  • Using the rotor diameter instead of the radius. The radius is half the diameter.
  • Forgetting to convert radius from mm to cm. Always use cm as required by the calculator.
  • Assuming the same RPM gives the same RCF on different rotors. RCF depends on rotor radius.

Last updated: August 13, 2026