What is RCF (relative centrifugal force)?

RCF is the effective force applied to the sample in a centrifuge, expressed as multiples of gravitational acceleration (×g). RCF = 1.118 × 10⁻⁶ × n² × R, where n is RPM and R is rotor radius in mm. Unlike RPM, RCF accounts for rotor size, making it comparable across different centrifuges.

Why should I use RCF instead of RPM in protocols?

RPM alone doesn't specify the actual force on the sample — it depends on rotor radius. Two centrifuges at the same RPM but different rotor sizes produce different g-forces. Scientific protocols specify RCF (×g) to ensure reproducible results regardless of the centrifuge model used.

What radius should I use — maximum, minimum, or average?

Use the maximum radius (r_max) — the distance from the rotation axis to the bottom of the sample tube — for the reported RCF. This gives the maximum g-force experienced by the sample. Some protocols specify r_avg (average) for sedimentation calculations.

What g-forces do different centrifuges achieve?

Typical ranges: benchtop microcentrifuges up to 20,000 ×g, general lab centrifuges 3,000–15,000 ×g, high-speed centrifuges 25,000–100,000 ×g, ultracentrifuges up to 1,000,000 ×g. Industrial separators typically operate at 1,000–10,000 ×g.

How do I convert g-force back to RPM?

Use the reverse formula: n = √(RCF / (1.118 × 10⁻⁶ × R)), where RCF is the desired g-force and R is rotor radius in mm. This calculator supports both directions — toggle between 'RPM → RCF' and 'RCF → RPM' modes.

Free Engineering Tool

Centrifuge G-Force (RCF) Calculator

Convert centrifuge RPM to relative centrifugal force (×g), or calculate RPM from desired RCF. Includes tip speed and angular velocity.

Vibromera engineers use this RPM to g conversion when preparing centrifuge rotors for field balancing with the Balanset-1A portable balancer.

RPM → RCF RCF → RPM Tip Speed

Results

Relative Centrifugal Force (RCF)

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RPM

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Tip Speed

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Angular Velocity ω

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Relative Centrifugal Force (RCF)

RCF is the effective force on the sample expressed as multiples of gravitational acceleration:

n — speed (RPM)
R — rotor radius in mm (center of rotation to sample position)
1.118 × 10⁻⁶ — combined constant from (2π/60)²/(9.81×1000)

Reverse: RPM from RCF

Typical RCF Values

Application	Typical RCF (×g)	Typical RPM
Blood separation	1,000–3,000	2,000–5,000
Cell pelleting	300–500	1,000–2,000
Protein precipitation	10,000–20,000	10,000–15,000
Subcellular fractionation	20,000–100,000	15,000–50,000
Ultracentrifugation	100,000–1,000,000	40,000–100,000
Industrial separators	1,000–10,000	3,000–10,000

Practical Example

Example — Lab Centrifuge

Given: R = 100 mm, Speed = 5000 RPM

RCF = 1.118 × 10⁻⁶ × 5000² × 100 = 2,795 ×g

ω = 2π × 5000 / 60 = 523.6 rad/s

Tip speed = 0.1 × 523.6 = 52.4 m/s

💡 Tip: Always report centrifuge conditions as RCF (×g) in scientific protocols, not RPM. This ensures reproducibility across different centrifuge models with different rotor sizes.