How to Use the Centrifugation Calculator
Select the conversion direction using the tabs — RPM → RCF or RCF → RPM. Enter the rotor radius (in mm or cm) and the speed value, then click Calculate. Use the quick preset buttons to auto-fill common rotor radii.
The Centrifugation Formula
RPM = √(RCF / (1.118 × 10⁻⁵ × r))
RCF = Relative Centrifugal Force in ×g | r = rotor radius in mm | RPM = revolutions per minute
Common Centrifugation Protocols
| Application | Typical RCF (×g) | Typical RPM* |
|---|---|---|
| Cell pelleting (mammalian cells) | 300 – 500 ×g | ~1,200 – 1,500 |
| Bacterial cell pelleting | 3,000 – 5,000 ×g | ~4,000 – 6,000 |
| DNA/RNA precipitation | 10,000 – 16,000 ×g | ~10,000 – 13,000 |
| Protein precipitation | 10,000 – 20,000 ×g | ~10,000 – 15,000 |
| Microcentrifuge max speed | 16,000 – 21,000 ×g | ~13,000 – 15,000 |
| Ultracentrifugation (virus pellet) | 100,000 – 200,000 ×g | ~35,000 – 50,000 |
* RPM values are approximate at r ≈ 107 mm (Eppendorf 5424 rotor)
About RPM vs RCF in Centrifugation
RPM (revolutions per minute) describes how fast the rotor spins but does not tell you the actual force applied to the sample — this depends entirely on the rotor radius. Two centrifuges running at the same RPM with different rotors will apply completely different forces to the sample.
RCF (Relative Centrifugal Force), expressed as ×g, is the universally comparable unit because it is independent of rotor size. When following published protocols, always use RCF (×g) values to ensure reproducibility across different instruments.