G Force Centrifuge Calculator

Example Data Table

Values are computed using the constant-form equation below.

Formula Used

Centrifugal acceleration is a = ω² r, and relative force is RCF = a / g.

When radius is in centimeters, a convenient constant is used:

The constant combines unit conversion and standard gravity.

How to Use This Calculator

1. Select a mode: g-force, RPM, or radius.
2. Enter radius or diameter using your rotor definition.
3. Fill RPM and g-force fields required for your mode.
4. Press Calculate to see results above the form.
5. Export history using the CSV or PDF buttons.

Article

1) Understanding g-force in centrifuges

RCF, or relative centrifugal force, reports acceleration at the sample as multiples of gravity. Separation depends on force, so RCF compares better than speed alone. The same RPM can create different forces when rotor size or tube position changes.

2) Radius is the hidden driver

Radius is the distance from the rotation center to the sample. Larger radius produces higher force at the same RPM. That is why two rotors on one centrifuge can differ. Enter radius directly, or enter diameter and it converts to radius.

3) Equation used for results

The calculator uses: RCF (x g) = 1.118 × 10⁻⁵ × r(cm) × RPM². The constant combines unit conversions and standard gravity. Keep radius in centimeters for this form, then convert the displayed radius to other units if needed.

4) Converting RCF and RPM

Protocols specify RCF so results transfer between instruments. If you know RCF and radius, the calculator rearranges the equation and solves RPM with a square root. Because RPM is squared, small speed increases raise force quickly. Stay under the rotor’s rated RPM.

5) Solving for effective radius

Some methods list both RPM and RCF, implying an effective radius. Use the radius mode to check that implied geometry matches your rotor and tube setup. It also helps compare fixed-angle and swing-bucket rotors, where sample radius differs.

6) Practical ranges and checks

Bench workflows may use a few hundred x g for clarification and tens of thousands x g for pelleting. A quick check: doubling RPM increases RCF about four times, while a 20% radius increase raises RCF 20%. These rules help validate entries. Check limits before long high-load rotor runs.

7) Exporting and documenting runs

Enable history to store recent runs, then export to CSV or PDF for documentation. Recording radius, RPM, and RCF improves repeatability and troubleshooting. Save exports with brief notes, dates, sample types, and protocol identifiers so the same force can be repeated across operators and rotor swaps.

FAQs

1) What is the difference between RPM and RCF?

RPM is rotational speed. RCF is the acceleration at the sample, expressed in multiples of gravity. RCF depends on both RPM and rotor radius, so it compares settings across rotors better.

2) Which radius should I enter?

Use the effective radius defined by your rotor manual, often the distance from the center to the bottom of the tube or sample. Use the same reference every run for consistency.

3) Why do protocols prefer RCF values?

RCF standardizes the applied force across instruments. RPM alone can produce different forces on different rotors. Using RCF helps keep pelleting and separation performance comparable.

4) Can I use diameter instead of radius?

Yes. Select the diameter input style and enter the rotor diameter with units. The calculator converts it to radius internally by dividing by two before solving.

5) What happens if I double RPM?

RCF increases about fourfold because RPM is squared in the equation. That rapid growth is why it is important to stay within rotor limits at high speeds.

6) Do CSV and PDF exports store my data permanently?

Exports are generated from the current session history. If the session resets, stored history may clear. Download CSV or PDF after important runs to keep records.