RPM to RCF converter
Convert centrifuge speed between rpm and g. Pick your rotor first: the same rpm gives very different force on a big rotor and a small one.
That's 4.8× as strong as separating plasma, while a hard spin-down is 1.26× higher. Your sample effectively weighs 9,503 times its own weight.
What it means
How hard is that spin?
Radii are to the bottom of the tube, where the force is highest. A protocol written for the middle of the tube will give a slightly lower figure.
Every unit
Your spin in every unit
Learn
Three things worth knowing
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RCF = 1.118 × 10⁻⁵ × r × rpm²
With r in centimeters. Because the speed is squared, doubling the rpm quadruples the force.
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Why "relative"
RCF compares the spin with ordinary gravity, so 1,000 g means the sample is pressed a thousand times harder than its own weight. That is what settles the pellet.
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rpm alone means nothing
10,000 rpm in a microcentrifuge is about 9,500 g; the same rpm in a big swinging-bucket rotor is over 20,000 g. Always record the g, or the rotor.
Shortcuts
Popular force conversions
Background
About RCF and rpm
A protocol says "spin at 12,000 g"; the machine has a dial in rpm. They are not the same thing: RCF depends on the rotor radius as well as the speed, and on the square of the speed at that.
Publishing a spin in rpm without the rotor is the reason so many protocols do not reproduce.