Centrifuge RPM/RCF Calculator

Convert between centrifuge speed in RPM and relative centrifugal force.

About Centrifuge RPM/RCF Calculator

RCF scales with the square of speed and linearly with radius, so the same RPM produces very different force in different rotors. Protocols should always specify RCF rather than RPM for that reason. Transferring an RPM figure between centrifuges with different rotor radii can change the applied force by a factor of two or more.

Formula

Centrifuge RPM/RCF

RCF = 1.118 × 10⁻⁵ × r(mm) × RPM²

RCF: Acceleration as a multiple of gravity, which is what determines pelleting
rotor radius: Distance from the axis to the sample, which varies by rotor

Worked example

With the default values below, Centrifuge RPM/RCF Calculator returns Relative Centrifugal Force of 1,368.4. Change any input above and every figure here is recalculated in your browser.

Inputs used

Rotor speedminimum 1 rpm: 12,000 rpm
Rotor radiusminimum 1 mm: 85 mm
Target relative centrifugal forceminimum 1 g: 15,000 g
Spin durationminimum 0.1 min: 10 min

Results

Relative Centrifugal Force: 1,368.4 g
RPM Needed for the Target RCF: 39,730 rpm
Angular Velocity: 1,256.64 rad/s
Integrated g-Minutes: 13,684 g.min
Rotor Tip Speed: 106.81 m/s

Step by step

1Values used
2Centrifuge RPM/RCF
3Relative Centrifugal Force= 1,368.4 g
4RPM Needed for the Target RCF= 39,730 rpm
5Angular Velocity= 1,256.64 rad/s
6Integrated g-Minutes= 13,684 g.min
7Rotor Tip Speed= 106.81 m/s

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Centrifuge RPM/RCF calculated?

RCF = 1.118 × 10⁻⁵ × r(mm) × RPM² RCF scales with the square of speed and linearly with radius, so the same RPM produces very different force in different rotors. Protocols should always specify RCF rather than RPM for that reason.

Why does Centrifuge RPM/RCF matter?

Transferring an RPM figure between centrifuges with different rotor radii can change the applied force by a factor of two or more.

What values do I need to enter?

This calculator takes 4 inputs: Rotor speed, Rotor radius, Target relative centrifugal force, Spin duration. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.