Why Relative Centrifugal Force Matters
Relative centrifugal force, often written as RCF, shows the effective acceleration applied to a sample during spinning. Many lab protocols list force in times gravity, not only revolutions per minute. That matters because two rotors can spin at the same speed and still create different force. The distance from the rotation center changes the final result. This calculator helps compare those setups with less guesswork.
Radius Accuracy
The rotor radius should be measured from the center of rotation to the bottom of the tube or bucket. Use the maximum sample position when the protocol expects maximum force. For swinging bucket rotors, the working radius may change after the bucket swings out. For fixed angle rotors, the tube bottom radius is often the clearest reference. Small radius errors can produce meaningful changes at high speed.
Speed Planning
Use the forward calculation when a protocol gives rpm and radius. Use the reverse rpm option when a protocol gives required RCF. This is useful when moving a method between centrifuges. The radius solving option helps check what rotor geometry would be needed for a chosen speed and force. Always respect the rotor, tube, and instrument speed limits.
Useful Outputs
The result includes force, speed, radius, acceleration, angular speed, and tip speed. These details help with method records and quality checks. CSV export is helpful for spreadsheets. PDF export is helpful for reports, notebooks, and shared method files.
Method Transfer
When a method moves to another centrifuge, rpm alone is not enough. The same listed speed may under spin or over spin a sample. RCF gives a better comparison because it joins speed and radius in one value. Keep one record for the original setup. Keep another record for the adjusted setup. Review both before running valuable samples. This prevents hidden differences during repeat testing and reviews.
Good Practice
Confirm units before each run. Clean the rotor chamber. Balance tubes carefully. Do not exceed rated speed. Inspect tubes for cracks. Match adapters to tube size. Record the rotor model when documenting results. When working with biological or chemical samples, follow the lab safety procedure. Use this calculator as a planning aid, then confirm important protocols with your equipment manual.