This free centrifuge speed reference covers 50+ common laboratory centrifugation protocols across mammalian cells, bacteria, organelles, nucleic acids, and proteins. Find the correct RPM and RCF (×g) values for your application at a glance — filterable by category and searchable by protocol name. Essential bench reference for molecular biology, cell biology, and microbiology labs.
| Protocol / Application | RPM* | RCF (×g) | Time | Temp | Notes |
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How to Use the Centrifuge Speed Reference
Step-by-Step Instructions
Search: Type a protocol name, sample type, or key term into the search box — for example "bacteria", "mitochondria", "DNA pellet", or "yeast" — to filter the table in real time. The search covers both protocol names and the notes column.
Filter by category: Use the filter buttons above the table to narrow results to a specific sample type: Cells (mammalian), Bacteria, Organelles, Nucleic Acids, or Protein. This helps quickly find the relevant g-force range for your experiment without scrolling through unrelated protocols.
RCF vs RPM: Always use RCF (×g) as your primary reference value when following or reporting protocols. RPM is rotor-dependent — the same RPM on two different centrifuges will produce different centrifugal forces if the rotor radii differ. The RPM values shown here are approximate estimates based on a rotor radius of ~10 cm.
Understanding RCF and RPM — The Formula
The relationship between RPM and RCF is given by the following formula, where r is the rotor radius measured from the axis of rotation to the sample position (in centimetres):
RCF (×g) = 1.118 × 10⁻⁵ × r × RPM²
RPM = √( RCF / (1.118 × 10⁻⁵ × r) )
// Example: r = 10 cm, RPM = 10,000
RCF = 1.118 × 10⁻⁵ × 10 × 10,000² = 11,180 × g
// Use the Centrifugation Calculator to convert for your exact rotor
To find the radius of your rotor, check the manufacturer's datasheet or measure from the centre of the spindle to the midpoint of the sample position in the tube. Most microcentrifuges have radii of 8–12 cm; large floor-model rotors can be 15–25 cm.
Types of Centrifuges Used in the Lab
Microcentrifuges (benchtop, 1.5–2.0 mL tubes): typically reach 14,000–21,000 × g; used for quick spins, precipitation pellets, and column-based DNA/RNA purification. Refrigerated low-speed centrifuges (for 15/50 mL conical tubes): typically 300–10,000 × g; used for cell harvest and washing. High-speed centrifuges: up to 100,000 × g; used for bacteria, organelle fractionation, and protein precipitations at scale. Ultracentrifuges: up to 600,000 × g; required for ribosomes, exosomes, viruses, and density-gradient separations. Always confirm that your tubes and rotor are rated for the g-force being applied.
When to Use This Reference
This table is most useful when: setting up a differential centrifugation protocol for organelle isolation; checking the correct spin for your cell type before harvest; troubleshooting poor DNA pellet recovery from ethanol precipitation; planning a viral particle concentration experiment; or verifying centrifuge settings when reproducing a protocol from a publication. The temperature column (4°C vs RT) is also critical — temperature-sensitive samples and enzyme-active preparations should almost always be centrifuged cold.
Common Mistakes to Avoid
Using RPM without converting to RCF: A protocol calling for "10,000 × g" cannot simply be run at 10,000 RPM — depending on your rotor, this may produce only 6,000 or as much as 16,000 × g. Always convert using the formula above or the Centrifugation Calculator.
Centrifuging at room temperature when 4°C is required: Many protocols call for cold centrifugation to slow enzymatic degradation, preserve protein complexes, and maintain organelle integrity. Running at RT when 4°C is specified — even briefly — can compromise downstream results.
Failing to balance tubes: Unbalanced loads create vibration that worsens at high speed. Always balance opposing tubes to within 0.1–0.5 g by mass, not volume. Imbalance is a primary cause of rotor bearing damage and can lead to catastrophic rotor failure at high speeds.
Exceeding the rotor or tube g-force rating: Polypropylene microcentrifuge tubes are typically rated to 16,000–25,000 × g; exceeding this can cause the tube to crack or collapse. Similarly, always check the rotor's maximum RCF in the instrument manual before selecting a spin speed.
Interpreting Your Results
The g-force ranges in this table represent established empirical values from the scientific literature and standard laboratory protocols. If your pellet is not visible or incomplete, consider increasing the speed toward the higher end of the listed range or extending the spin time. Conversely, if you observe loss of a labile fraction (e.g. fragile organelles or large macromolecular complexes), reduce to the lower end of the range. Temperature-sensitive pellets should always be resuspended on ice, and supernatants kept cold throughout downstream processing.
Frequently Asked Questions
What is the difference between RPM and RCF (×g) in centrifugation?
RPM (revolutions per minute) measures rotor spin rate, while RCF (relative centrifugal force, expressed as ×g) measures the actual centrifugal force applied to the sample. RCF is the scientifically meaningful value because two rotors at the same RPM but with different radii produce entirely different forces. The conversion is: RCF = 1.118 × 10⁻⁵ × r × RPM², where r is the rotor radius in centimetres. Always use RCF as the primary reference value in protocols — different labs and instruments may need different RPM settings to reach the same RCF. This table lists both values, with RPM estimates based on a ~10 cm rotor radius.
What centrifuge speed should I use to pellet E. coli bacteria?
E. coli cells are typically pelleted at 3,000–6,000 × g for 10–20 minutes at 4°C. For small volumes (1–2 mL) in a microcentrifuge, 6,000–8,000 RPM for 10 minutes is standard. For larger culture volumes (50–500 mL), a floor-model high-speed centrifuge at 4,000–6,000 RPM for 15–20 minutes is typical. For transformation recovery after heat shock, a brief 1-minute spin at 3,000–5,000 RPM is sufficient before resuspension. Centrifuge at 4°C to preserve cell viability and protein stability for downstream applications.
How do I isolate mitochondria by differential centrifugation?
Mitochondria isolation requires sequential spins at increasing speeds. After homogenising cells in isotonic sucrose buffer on ice, centrifuge at 200–300 × g for 10 minutes to pellet nuclei and intact cells — save the supernatant. Then spin at 1,000–3,000 × g for 10 minutes to remove residual debris. Finally, spin at 10,000–12,000 × g for 10–15 minutes at 4°C to pellet the crude mitochondrial fraction. This pellet can be further purified by Percoll or sucrose density gradient centrifugation. All steps must be performed on ice to maintain mitochondrial integrity and membrane potential.
What speed is needed to pellet DNA in an ethanol precipitation?
DNA ethanol precipitation requires at least 12,000–16,000 × g for 15–30 minutes at 4°C. The high force compacts even trace amounts of DNA against the tube wall — the pellet may be completely invisible at low concentrations. Note the tube orientation in the rotor (hinge side out) before spinning so you know where to look for the invisible pellet. After centrifugation, carefully aspirate the ethanol, wash with 70% ethanol at 7,500–10,000 × g for 5 minutes, and air-dry the pellet before resuspension in water or TE buffer.
Why is centrifuge tube balance so important, and how precise does it need to be?
Opposing tubes in a centrifuge rotor must be balanced to within 0.1–0.5 g for microcentrifuges and 0.5–1.0 g for large rotors — consult your instrument manual for exact tolerances. Balance by mass on a scale, not by volume, since liquids have different densities. Unbalanced loads cause vibration that increases exponentially with speed, risking bearing damage, premature rotor wear, and in extreme cases catastrophic rotor failure. If you have an odd number of samples, create a balance tube with equal mass using water or buffer. Fixed-angle rotors tolerate minor imbalance better than swing-bucket rotors, but both must always be balanced.