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Formula Calculate Relative Centrifugal Force (RCF)
Calculation of RCF
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RCF Calculator

CALCULATOR FOR CALCULATION OF G FORCE OR RCF (RELATIVE CENTRIFUGAL FORCE)

RCF / RPM Calculator

RCF / RPM Calculator

Formula (r in cm): RCF = 1.118 × 10-5 × r × RPM²
K constants: cm 1.118e-5 · mm 1.118e-6 · in 2.80e-5

How to Calculate Relative Centrifugal Force (RCF)

Relative Centrifugal Force (RCF), often called g force, expresses how strongly a centrifuge accelerates samples relative to Earth’s gravity. It depends on both the rotor speed (RPM) and the rotational radius r.

Core Formula (r in centimeters)

RCF = 1.118 × 10−5 × rcm × RPM²

An equivalent rearrangement many labs use is:

RCF = (RPM / 1000)² × rcm × 11.18

RCF = (RPM/1000)^2 × r × 11.18 ⇒ RPM = √(RCF/(r × 11.18)) × 1000
Equivalent forms of the RCF/RPM relationship (r in cm).

Solving for RPM (Given a Target RCF)

RPM = √[ RCF / (1.118 × 10−5 × rcm) ]

or   RPM = √[ RCF / (rcm × 11.18) ] × 1000

Variable Definitions

  • RCF (g): Relative centrifugal force (dimensionless multiple of gravity).
  • RPM: Rotor speed in revolutions per minute.
  • r: Radius — distance from the axis of rotation to the bottom of the sample tube. Unless noted otherwise, use centimeters.

Constants for Other Radius Units

Radius unit Use this constant K in “RCF = K × r × RPM²”
cm 1.118 × 10−5
mm 1.118 × 10−6
inches 2.80 × 10−5

Example

For RPM = 3750 and r = 23.4 cm:

RCF = 3750² × 1.118 × 10−5 × 23.4 ≈ 3276 g