RPM ↔ RCF conversion (relative centrifugal force)
RCF = 1.118 × 10⁻⁵ × r × RPM²
Calculate the RCF (in × g) from the rotation speed in RPM and the rotor radius, or the reverse, with the formula RCF = 1.118 × 10⁻⁵ × r × RPM².
Scientific dossier
What the tool computes, what it assumes, where it stops being valid, and where its data comes from.
Method & formulasRCF = 1.118 × 10⁻⁵ × r × RPM²
RCF = 1.118 × 10⁻⁵ × r × RPM²
The radius r is expressed in centimeters. The RCF (Relative Centrifugal Force) is expressed as a multiple of the acceleration due to gravity (× g).
- RPM
- · the rotation speed of the rotor, in revolutions per minute.
- r
- · the rotor radius, the distance between the rotation axis and the sample.
- RCF
- · the relative centrifugal force applied to the sample, in × g.
Validity domainUse the actual distance between the rotation axis and the sample, never the rotor diameter.
Use the actual distance between the rotation axis and the sample, never the rotor diameter. On a fixed-angle rotor, this radius varies slightly between the top and bottom of the tube; laboratory protocols usually specify whether to use the minimum, maximum or average radius. Check the rotor's datasheet.
ExampleA rotor with a 10 cm radius spinning at 5,000 rpm applies a relative centrifugal force of about 2,795 × g (1.
A rotor with a 10 cm radius spinning at 5,000 rpm applies a relative centrifugal force of about 2,795 × g (1.118×10⁻⁵ × 10 × 5000² ≈ 2,795).