About this tool
Centrifuge RPM ⇄ G-Force / RCF Calculator is a free, in-browser tool that converts between a centrifuge's rotational speed (RPM) and the relative centrifugal force (RCF), measured in multiples of gravity (×g). Choose which way to solve, enter the rotor radius in millimetres, centimetres or inches, and read the answer instantly. Nothing is uploaded.
The conversion uses RCF = 1.118 × 10⁻⁶ · r · RPM², where r is the rotor radius in millimetres — the same as the textbook form 1.118 × 10⁻⁵ · r · RPM² with r in centimetres. To go the other way it inverts the formula: RPM = √(RCF ÷ (1.118 × 10⁻⁶ · r)). The radius you enter is converted to millimetres first, so a 100 mm radius spinning at 3000 RPM gives about 1006 ×g.
Use it to reproduce a protocol written in ×g on your own centrifuge, or to report the RCF for a given speed. Because RCF depends on the radius, always use the value for your specific rotor to match a published method.