Advanced Centrifuge Input Panel
Enter rotor distance and speed data. The result appears above this form.
Formula Used
The calculator uses centripetal acceleration and relative centrifugal force.
a = ω²r RCF = a / g RCF = 1.118 × 10⁻⁵ × r(cm) × RPM² RPM = √(RCF / (1.118 × 10⁻⁵ × r(cm)))Here, r is the radius from the rotation axis. RPM is revolutions per minute. RCF is the g force multiplier.
How to Use This Calculator
- Select the calculation mode.
- Enter rotor radius or rotor diameter.
- Choose the correct distance unit.
- Enter RPM, angular velocity, period, or target RCF.
- Add sample mass and rotor limit when needed.
- Press the calculate button.
- Review acceleration, RCF, speed, and safety notes.
Understanding Centrifuge G Force
Centrifuge g force describes relative centrifugal force. It compares spinning acceleration with ordinary gravity. A value of 1000 × g means one thousand times gravity. The value depends on radius and speed. Speed has the strongest effect. Doubling RPM makes force four times larger.
Why Radius Matters
Rotor radius is the distance from the rotation axis. Use the sample position, not just rotor size. A sample near the outer end feels more acceleration. A sample near the center feels less acceleration. This is why two rotors can differ at the same RPM.
RPM and RCF Are Different
RPM only reports rotational speed. It does not include rotor radius. RCF includes both speed and radius. Laboratory methods often state RCF instead of RPM. That makes methods easier to repeat across different centrifuges.
Angular Velocity View
Physics often uses angular velocity. Its unit is radians per second. The equation a = ω²r uses this value directly. The calculator converts RPM into angular velocity. It also converts period into RPM when selected.
Reverse Speed Planning
Sometimes a protocol gives a target RCF. In that case, choose the target mode. Enter the required RCF and rotor radius. The calculator returns the needed RPM. Always compare it with the rotor rating. Never exceed the manufacturer limit.
Acceleration and Sample Force
Centrifugal acceleration is reported in meters per second squared. RCF converts that acceleration into a gravity multiplier. The calculator can also estimate sample force. It multiplies sample mass by acceleration. This helps compare loads during high speed operation.
Tip Speed and Spin Time
Tip speed shows how fast the rotor edge moves. It can be shown in meters per second, kilometers per hour, and miles per hour. Spin time estimates total revolutions. This is useful when comparing runs with different durations.
Practical Accuracy Notes
Use the real sample radius for best accuracy. Rotor catalogs may list maximum radius. Tubes can sit at angles. Swinging bucket rotors can change radius during operation. Fixed angle rotors may use mean radius. Choose the value that fits your protocol.
Safety Reminder
High RCF can stress tubes, caps, buckets, and shafts. Inspect rotor condition before use. Match tubes with rated speed. Balance opposite positions carefully. Stop the run if vibration appears. This calculator supports planning only. Manufacturer guidance remains the final safety reference.
Common Laboratory Use
Biology, chemistry, and clinical labs use centrifuges daily. They separate cells, proteins, pellets, and liquids. Accurate RCF improves repeatability. It also protects samples from excessive force. Use consistent units and record settings carefully.
Example Data Table
| Radius | RPM | Approximate RCF | Typical use |
|---|---|---|---|
| 8 cm | 3000 | 805 × g | Gentle sample separation |
| 10 cm | 5000 | 2795 × g | Cell pellet formation |
| 12 cm | 10000 | 13416 × g | High speed processing |
| 15 cm | 15000 | 37733 × g | Dense particle separation |
FAQs
What is g force in a centrifuge?
It is relative centrifugal force. It compares spinning acceleration with normal gravity. A result of 2000 × g means the sample feels two thousand times gravity.
Is RPM the same as RCF?
No. RPM is rotational speed only. RCF uses RPM and rotor radius. The same RPM can create different force in different rotors.
Which radius should I enter?
Enter the distance from the rotation axis to the sample position. Use maximum, minimum, or mean radius according to your lab protocol.
Why does RPM have a squared effect?
Centripetal acceleration depends on angular velocity squared. That means small speed changes can strongly change the final g force.
Can I calculate RPM from target RCF?
Yes. Select target mode. Enter the desired RCF and rotor radius. The calculator returns the required RPM.
What gravity value should I use?
Standard gravity is 9.80665 m/s². Most lab calculations use that value. You may enter a local value when precision matters.
Does tube angle affect the result?
Tube angle can affect the real sample path. Fixed angle rotors often use mean radius. Check your rotor guide for recommended radius.
What is tip speed?
Tip speed is the linear speed at the rotor radius. It helps show how fast the outer sample path moves.
Can this tool replace rotor safety limits?
No. Always follow the centrifuge and rotor manufacturer limits. The calculator is only a planning and conversion aid.
Why is RCF useful in protocols?
RCF makes protocols more repeatable. It accounts for rotor size. RPM alone may not transfer correctly between machines.
Can I download the result?
Yes. Use the CSV or PDF buttons after entering values. Each file records the main calculated results.