What is the revolutions per minute (rpm) equivalent of a 150-200 g-force in a centrifuge?

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Converting G-Force to RPM in Centrifugation

The conversion of 150-200g to RPM depends critically on the radius of your specific centrifuge rotor, but for a typical laboratory centrifuge with a radius of 10-15 cm, 150-200g corresponds to approximately 1,200-1,700 RPM.

Understanding the Relationship

The relationship between relative centrifugal force (RCF, measured in g-force) and revolutions per minute (RPM) is not direct—it depends on the radius of the centrifuge rotor 1. Guidelines strongly recommend documenting and using RCF (g-force) rather than RPM in standard operating procedures and publications, as RPM alone is insufficient without knowing the rotor radius 1.

The Conversion Formula

The mathematical relationship is:

RCF (g) = 1.118 × 10⁻⁵ × r × (RPM)²

Where:

  • RCF = relative centrifugal force in multiples of gravity (g)
  • r = radius in centimeters (measured from the axis of rotation to the bottom of the tube)
  • RPM = revolutions per minute

2

Practical Examples by Rotor Radius

For 150g force:

  • At r = 10 cm: approximately 1,160 RPM
  • At r = 12 cm: approximately 1,060 RPM
  • At r = 15 cm: approximately 950 RPM

For 200g force:

  • At r = 10 cm: approximately 1,340 RPM
  • At r = 12 cm: approximately 1,225 RPM
  • At r = 15 cm: approximately 1,095 RPM

2

Clinical Context

Low g-force centrifugation (150-200g) is commonly used for initial separation of blood components, particularly for removing cells while preserving platelets and larger extracellular vesicles 1. For plasma preparation in biomarker studies, the first centrifugation is typically performed at 2000g for 10 minutes to separate plasma from cells 1. The 150-200g range represents a gentler separation suitable for applications where you want to retain certain cellular elements or large vesicles 1.

Critical Considerations

  • Always verify the specific radius (rmax) of your centrifuge rotor—this information should be available in the manufacturer's specifications or rotor documentation 2
  • The radius is measured from the center of rotation to the bottom of the tube when seated in the rotor 2
  • Different positions within the same rotor may experience slightly different g-forces due to varying distances from the axis of rotation 1
  • Ensure the centrifuge is on a stable surface to prevent vibration, which can affect the actual force applied 1

Common Pitfall

The most common error is using RPM values from one centrifuge on a different centrifuge with a different rotor radius—this will result in significantly different g-forces and potentially compromise your results 1. Always calculate or verify the actual g-force for your specific equipment.

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Research

Centrifuges and rotors.

Current protocols in human genetics, 2001

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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