Convert between RPM and relative centrifugal force (× g) for any rotor radius. Batch mode, methods-section snippet, and CSV export. Data never leaves your browser.
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RCF
18,625.9 × g
RPM
14,000
RCF
18,625.9 × g
Radius
85.0 mm
Radius is measured from the center of rotation to the bottom of the tube (rmax). This is the distance used in all RCF calculations.
When to use
Do not use for
Journals increasingly require this. Our "Copy for Methods" button formats it correctly for manuscripts.
r_max gives the maximum force your sample experiences. Using mid-point radius underestimates force by 10–30%.
Switching from a 24-place rotor (small radius) to an 8-place rotor (large radius) at the same RPM significantly changes RCF. Always recalculate when switching rotors.
Applies the canonical formula RCF = 1.118 r(cm) (equivalently 1.118 r(mm) ), derived from the angular acceleration ω²r normalised by Earth's gravity g 9.81 m/.
Last validated 2026-04-08. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.
ConductScience RCF/RPM Calculator (v1.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/rcf-rpm-calculator
Rickwood D, Ford T, Steensgaard J. Centrifugation: Essential Data. John Wiley & Sons, 1994.
Ohlendieck K, Harding SE. Centrifugation and Ultracentrifugation. In: Principles and Techniques of Biochemistry and Molecular Biology. Cambridge University Press, 2018.
RCF (relative centrifugal force) measures the actual force applied to a sample, expressed as multiples of gravitational acceleration ( g). Unlike RPM, RCF accounts for rotor radius — the same RPM on two different rotors produces different forces.
Rotor radius is the distance from the center of rotation to the bottom of the sample tube (or the furthest point of the sample in the tube). This is NOT the rotor diameter. Check your rotor manufacturer's documentation for the exact r_max value.
Most journals require centrifugation forces reported as g (RCF), not RPM. Reporting RPM alone is insufficient because readers with different rotors cannot reproduce the conditions. Always include both RPM and RCF, plus rotor model if possible.
