Understanding RCF and RPM: Demystifying the Differences in Centrifuges

Feb 13,2024

In the selection process of an appropriate centrifuge, a paramount factor to closely evaluate is its maximum speed.

Notably, there are two significant speed indicators in the field of centrifuges: RCF (Relative Centrifugal Force) and RPM (Revolutions Per Minute).

While these terminologies are commonly substituted for one another due to their relation to speed, they do represent disparate measurements. This article explains the difference between the two terms and why RCF is more relevant to centrifuges.

What are RCF and RPM?

The “RCF” denotes the term “Relative Centrifugal Force”, while “RPM” corresponds to “Revolutions Per Minute.” These represent distinct physical measurements, their relationship being primarily influenced by the centrifuge’s rotational speed and radius.

Relative centrifugal force (RCF)

Relative Centrifugal Force’ (RCF) refers to a critical unit frequently employed in the operation of a centrifuge, instrumental in quantifying the amount of centrifugal force exerted on a sample. Intrinsically tied to both the speed of the centrifuge and its radial extent, RCF plays an invaluable role across fields such as biology and chemistry.

In laboratory settings engaging these disciplines, various components within liquid mixtures—for instance, precipitated cells or particles—require separation for further analysis. This process is aptly undertaken using RCF through centrifugation procedures that offer requisite efficacy and precision.

Revolutions per minute (RPM)

Revolutions Per Minute (RPM) is a standard unit utilized to ascertain the rotational velocity of an object within a span of one minute. This unit is imperative in delineating the operational speed of mechanical equipment such as engines, motors, fans and their analogous devices.

RPM proffers pivotal informational insights concerning these devices’ performance metrics. The derivation of this crucial parameter entails quantifying the number of comprehensive revolutions executed by a particular shaft during a time duration encompassing sixty seconds.

Revolutions per minute (RPM)

Difference Between RCF and RPM

While both RCF and RPM pertain to the operation of centrifuges, each term signifies a distinct aspect. RCF delineates the authentic gravitational force engendered by the rotation of the centrifuge drum. In contrast, RPM represents the velocity at which this drum rotates.

Consequently, determining RCF requires an understanding of its correlation with RPM as well as accounting for the radius of said rotating object.

How to Translate RPM to RCF

The empirical equation to calculate the Relative Centrifugal Force incorporates RPM and a rotational radius defined in centimetres. Specifically, it follows RCF = (RPM)² * 1.118 * 10-5 * r.

Where RPM signifies the amount of rotor revolutions completed per minute, while r constitutes the measurement of centrifugation distance or rotary radius. This formula is instrumental for effective conversion from RPM into corresponding RCF values.

How to Translate RPM to RCF

This measurement is convertible between different-sized centrifuges, so most protocols will detail what you need in the RCF

Factors influencing the choice of RCF and RPM

The selection of the suitable RCF and RPM is contingent upon an array of factors, encompassing the following:

Sample Characteristics

The attributes of a sample, including density, viscosity, shape, and size, play a significant role in determining the ideal centrifugation conditions. For instance, lighter (less dense) or smaller samples may necessitate a higher Relative Centrifugal Force (RCF) to achieve proper separation.

Various types of samples, such as cells, proteins, or pellets, may require different centrifugation conditions. Adjusting both RCF and RPM according to the sample’s characteristics facilitates optimal centrifugation outcomes.

Application Requirements

Distinct experimental objectives may demand specific centrifugation conditions. For instance, situations requiring swift sample separation may necessitate higher RCF and RPM. Certain applications, like cell culture or protein purification, mandate stringent centrifugation conditions to ensure sample purity and integrity.

Centrifuge Type and Capacity

Different centrifuge models offer varying maximum RCF and RPM ranges. Additionally, the rotor type and capacity influence optimal centrifugation conditions. Ensuring compatibility between the centrifuge, rotor, and sample container size and shape is essential.

Sample Protection

For sensitive samples, such as cells or RNA, avoiding excessive centrifugal force and rotational speed is imperative to prevent sample damage. When setting centrifugation conditions, you should strike a balance between sample protection and separation efficiency.

Huading Disc Stack Centrifuge

In a disc stack centrifuge, the RCF is a pivotal factor that distinguishes it from other types of centrifuges. Unlike simple open-bowl or decanter centrifuges, our disc centrifuge harnesses a significantly higher centrifugal force (g-force)/RCF. This elevated force empowers the disc-stack centrifuge with superior separation efficiency.

Our state-of-the-art disc stack separators excel at isolating even ultra-fine particles, thereby far surpassing the performance capabilities typical to alternative centrifuge types.

Furthermore, these sophisticated machines are designed also to efficiently manage immiscible liquids – even those possessing bare minimal specific gravity differentials – all thanks to their remarkable g-force maximization feature.

Huading Disc Stack Centrifuge


Understanding the differences between RCF and RPM is crucial for selecting the right centrifuge for your laboratory needs. RCF measures the relative centrifugal force, while RPM measures the revolutions per minute.

It is important to consider both factors when choosing a centrifuge to ensure accurate and efficient sample separation. At Huading, we provide high-quality centrifuges that meet the needs of various industries. Contact us today to find the perfect centrifuge for your industry requirements.

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