How do you convert RPM to RCF?
RCF (x g) = 1.118 x 10⁻⁵ x r x RPM², with r in centimetres from the center of the rotor to the sample (Thermo Scientific Pierce Tech Tip #40). Worked example from that source: 5,000 RPM at a 7 cm radius gives 1.118 x 10⁻⁵ x 7 x 5,000² = 1,957 x g.
How do you convert x g to RPM?
Rearrange the same formula: RPM = √(RCF ÷ (1.118 x 10⁻⁵ x r)). Because RCF depends on the radius, the same RPM gives a different force in a different rotor, which is why protocols should state x g rather than RPM.
How do I find my rotor radius?
Look it up in the rotor's manual or on the rotor itself. Manuals often give a minimum, average and maximum radius; protocols usually mean the maximum radius unless they say otherwise. Enter it in cm or mm, and the calculator converts.
Frequently asked questions
What is the difference between RPM and RCF?
RPM is how fast the rotor turns; RCF is the force the sample feels, as a multiple of gravity (x g). RCF depends on both speed and radius, so it is the value that transfers between centrifuges.
Is RCF the same as g?
RCF is expressed in multiples of g, Earth's gravity. 1,000 x g means a force 1,000 times gravity.
What is the RCF formula?
RCF = 1.118 x 10⁻⁵ x r (cm) x RPM².
How many g is 13,000 RPM?
It depends on the rotor radius. At an 8 cm radius, 13,000 RPM is about 15,100 x g; at 6 cm it is about 11,300 x g. Enter your radius to check.
Should I use the minimum or maximum radius?
Use the one your protocol specifies. If it does not say, the maximum radius is the common convention.
Is anything I enter saved or sent?
No. The calculator runs in your browser. Nothing you type is saved, sent to BioBridgeX or added to the page address, and analytics never see your numbers.
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