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Centrifuge RPM to RCF Converter

Convert between centrifuge speed (RPM) and relative centrifugal force (RCF / x g) using rotor radius. Works in both directions.

Enter RPM to calculate RCF, or RCF (x g) to calculate RPM.
Distance from rotor center to sample in cm (see rotor spec sheet).

Results

RCF (x g) -- use if input was RPM2,795 x g (RCF)
RPM -- use if input was RCF6,688 RPM

📖What is it?

RPM (rotations per minute) describes how fast a rotor spins, but the actual force on the sample depends on rotor size. RCF (relative centrifugal force, in x g) is rotor-independent and reproducible across any centrifuge. The formula is: RCF = 1.118 x 10^-5 x r x RPM^2, where r is rotor radius in cm.

🎯How to use

Enter a value and your rotor radius. Both outputs are shown simultaneously: if you entered RPM, read the RCF row; if you entered RCF/x g, read the RPM row. Rotor radius (r) is typically found in your centrifuge manual or the rotor label.

💡Example scenario

A bench-top centrifuge with a 10 cm rotor at 5,000 RPM: RCF = 1.118 x 10 x 25,000,000 / 100,000 = 2,795 x g. To pellet bacteria (10,000 x g needed), with 10 cm rotor: RPM = sqrt(10,000 x 100,000 / (1.118 x 10)) = 9,464 RPM.

🏆Pro tip

Common protocol benchmarks: 300-400 x g = mammalian cell pelleting; 800 x g = platelet-rich plasma; 2,000-3,000 x g = yeast; 10,000 x g = bacterial cells; 100,000+ x g = ultracentrifugation for ribosomes and viruses. Always use RCF in published protocols for reproducibility.