Centrifuge Rcf
Calculator
Results
- Relative centrifugal force (× g)
- 1,699.36
- Rotor radius (cm)
- 9.5
- Angular velocity (rad/s)
- 418.87902
Biology and lab results
| Relative centrifugal force (× g) | 1,699.36 |
| Rotor radius (cm) | 9.5 |
| Angular velocity (rad/s) | 418.87902 |
formula-map diagram
- Relative centrifugal force (× g)
- 1,699.36
- Rotor radius (cm)
- 9.5
- Angular velocity (rad/s)
- 418.87902
Formula breakdown
Formula
RCF = 1.118 × 10⁻⁵ × r(cm) × RPM²= 1699.36
Note
Simplified model: these results use standard textbook laboratory relationships and average constants (A260 = 1 for 50 µg/mL dsDNA, 617.96 g/mol per base pair, ~110 Da per amino acid, ideal exponential growth). Real samples vary with purity, contaminants, buffer, temperature and instrument calibration. Always confirm against your own standards and protocol; do not use for diagnostic or safety-critical work.
More in Biology and lab
See all →Frequently asked questions
What is the difference between RCF and RPM?+
RPM (revolutions per minute) is simply the rotor's rotational speed, while RCF (relative centrifugal force), expressed in multiples of gravity (x g), is the actual force experienced by the sample, which depends on both RPM and the rotor's radius. Protocols specify RCF because it is independent of which centrifuge or rotor you use.
What is the formula used to convert RPM to RCF?+
RCF = 1.118 x 10⁻⁵ x r x RPM², where r is the radius in centimeters from the center of the rotor to the sample (usually the bottom of the tube). The calculator asks for RPM and radius and applies this constant.
Why do I need the rotor radius, and where do I find it?+
Because centrifugal force increases with distance from the axis of rotation, the same RPM produces different RCF values on rotors of different sizes; the radius is specified in the rotor's manual or printed on the rotor itself, usually as the maximum radius to the tube bottom.
Should I use the radius to the top or bottom of the tube?+
Protocols almost always specify RCF at the maximum radius, meaning the bottom of the tube where the pellet forms, since this is where the greatest force is applied; using the minimum (top) radius instead will underestimate the actual RCF experienced by the sample.
Why does the same RPM give different results on different centrifuges?+
Because RCF depends on rotor radius, not just RPM, two centrifuges with different rotor sizes running at the identical RPM will subject samples to different actual forces, which is exactly why protocols should be followed by target RCF (x g) rather than by RPM alone.