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Centrifuge Calculator

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RCF vs. RPM – centrifuge rotor's speed unitsHow to convert RPM to RCF?How to convert RCF to RPM?FAQs

With the centrifuge calculator, you can quickly convert between RCF and RPM (relative centrifugal force and revolutions per minute). We created this tool to help you use a centrifuge in your job or studies. Read on to learn which of these – RPM or RCF – is a universal parameter. You'll also learn how to calculate one if you know the other.

Want to learn the physics behind a centrifuge? Go to the centrifugal force calculator!

RCF vs. RPM – centrifuge rotor's speed units

Imagine this scenario: You work in your lab just as usual when you notice – your centrifuge is broken, and you have to use a different one. But how should you set it up so your probes are centrifuged in precisely the same way as before? There is one ruleuse the same RCF as before.

RCF means relative centrifugal force, and its value corresponds to how high the force acting on the centrifuged items is, compared to gravitational force. That's why you can often see ×g next to the RCF value.

RPM means a rotor's revolutions (or rotations) per minute in the centrifuge. In other words, it describes how fast the rotor is spinning. Even if two centrifuges with different motors rotate at the same speed (have the same RPM), the force acting on a centrifuged item depends on the radius of a particular rotor.

💡 If you want to perform an experiment the same way every time, the force acting on your probes should always be the same. So RCF must stay constant, while RPM (rotor's speed) might differ on different centrifuges.

How to convert RPM to RCF?

To calculate RCF, apart from the rotor's speed (RPM), you also need to check its radius. When you know the rotor's radius in centimeters, you can use the formula:

RCF = 11.18 × radius × (RPM/1000)²

The two constant numbers in the formula come from unit conversions (the formula doesn't use standard SI units that you would normally use when calculating centrifugal force) and relativization with respect to the gravitational pull of the Earth.

If you prefer using online tools, in our centrifuge calculator, just input the RPM and radius in any unit you want, and get the result in a blink.

🙋 Did you know that RPMs are also used in engine mechanics? Learn more in the rpm calculator.

How to convert RCF to RPM?

If your centrifuge doesn't have the option to set RCF value, you might have to use RPM. To convert RCF to rpm:

  1. Check the rotor's radius in centimeters.
  2. Use the formula:
    RPM = √(RCF/(radius × 11.18)) × 1000
  3. That's it! You can check your result in our centrifuge calculator!

🙋 If you work with a centrifuge, you might also work with cells. Before you go, check if our cell doubling time calculator would help you with your work.


How do I convert 14000 RPM to RCF?

To convert RPM to RCF:

  1. Check the radius of a rotor in the centrifuge you're using and convert it to centimeters.

  2. Use RPM to RCF equation:

    RCF = 11.18 × radius × (RPM/1000)²

  3. You've got your result!

For example, if the rotor's radius equals 5 cm, the centrifuge would spin the samples with almost 11 thousand g. You can check the RCF value for different radiuses and RPMs in our RPM to RCF calculator.

What's the difference between RCF and RPM?

RCF (relative centrifugal force) corresponds to the force acting on a sample in a centrifuge. RPM (revolutions per minute) means how fast the rotor in a centrifuge is spinning. When using RPMs, you should always look out for your rotor size (particularly radius) as it influences the force acting on your samples.

Visit our centrifuge calculator to learn how to convert between these two parameters.

Is RCF the same as g?

RCF is the relative centrifugal force and is expressed as a multiple of gravitational force (g). Whether you choose RCF or g on a centrifuge, it doesn't matter. The same value of RCF and g means that your samples will be spun with the exact same force.

How to calculate g from RPM?

To calculate g (or RCF) from RPM, you need the know the radius (in centimeters) of the rotor you're using. Then, you can use this rpm to g formula:

g = 11.18 × radius × (RPM/1000)²

If you need a quick converter, you can use our RPM to RCF calculator.

Radius of the rotor

Input one and get the other

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