Advanced Calculator
Enter a force value and rotor radius to convert g-force into RPM. You can also reverse the calculation.
Example Data Table
| g-force | Radius | Required RPM | Use Case |
|---|---|---|---|
| 500 × g | 8 cm | 2,364 RPM | Gentle sample pelleting |
| 1,000 × g | 8 cm | 3,344 RPM | General low speed separation |
| 2,000 × g | 10 cm | 4,230 RPM | Cell wash planning |
| 5,000 × g | 12 cm | 6,105 RPM | Medium force separation |
| 10,000 × g | 7 cm | 11,304 RPM | High speed microtube run |
| 16,000 × g | 8.5 cm | 12,976 RPM | Compact rotor protocol |
Formula Used
The calculator uses the standard relative centrifugal force relation:
RCF = 1.118 × 10⁻⁵ × r × RPM²
Here, RCF is force in multiples of g. The value r is rotor radius in centimeters. To find RPM, the equation becomes:
RPM = √(RCF ÷ (1.118 × 10⁻⁵ × r))
The correction factor multiplies the target or calculated force. Keep it at 1 for normal conversions.
How to Use This Calculator
- Select whether you want to convert g-force to RPM or RPM to g-force.
- Enter the target g-force or RPM value.
- Enter the rotor radius and choose the correct unit.
- Add a maximum safe RPM if you want a warning check.
- Add spin time if you want total revolutions.
- Click the calculate button to show the result above the form.
- Use CSV or PDF download buttons to save the result.
G to RPM Conversion Guide
Why this calculator helps
Rotor speed is easy to read on a centrifuge. Yet separation depends on relative centrifugal force. That force changes with rotor radius. A small benchtop rotor and a large swing bucket rotor can produce different force at the same RPM. This calculator links those values in one clear place.
Better lab planning
The tool is useful for labs, classrooms, and process notes. Enter the target g value and the effective radius. The page returns the required RPM. You can also switch modes and enter RPM to estimate g. This helps when a protocol gives one value, but your instrument needs the other.
Radius matters
The radius field accepts millimeters, centimeters, and inches. Use the distance from the rotor center to the sample position. For swing bucket rotors, use the maximum running radius. For fixed angle rotors, use the stated effective radius from the rotor manual. Good radius data gives better results.
Advanced options
Advanced options make the result more practical. Add a maximum safe RPM to flag overspeed risk. Add spin time to estimate total revolutions. Use decimal control for cleaner reports. A correction factor is also available for internal calibration notes. Keep it at 1 unless your lab has a documented reason.
Exports and checks
The result card appears before the form after calculation. It shows the main value, converted radius, formula steps, safety status, and optional revolution count. You can export the result as CSV or PDF. This is helpful for worksheets, audit trails, and shared method files.
Good record habits
Use clean units when copying data from protocols. Many papers list force as x g. Others list speed as RPM with a named rotor. The named rotor matters because radius controls the conversion. If that radius is missing, look it up before using the value. Avoid guessing when samples are fragile or hazardous.
Safety note
The example table shows common RCF and radius combinations. It is not a replacement for rotor limits. Always follow the centrifuge maker rating, tube rating, and sample safety rules. Use this calculator for planning and conversion. Confirm critical settings before every run.
For best records, save the radius, mode, target value, result, and date. Simple notes make repeated runs easier to review later and share with teammates.
FAQs
What does g mean in centrifuge settings?
It means relative centrifugal force. It compares the force created by spinning to normal gravity. A value of 1,000 × g means the sample feels one thousand times normal gravitational force.
Why do I need rotor radius?
RPM alone does not define separation force. A larger radius creates more force at the same speed. That is why radius is required for accurate g to RPM conversion.
Which radius should I enter?
Use the effective radius from the rotor manual. It is usually the distance from the center of rotation to the sample position. Use maximum radius for swing bucket rotors.
Can this calculator convert RPM back to g?
Yes. Select RPM to g-force mode. Enter RPM and radius. The calculator will estimate the relative centrifugal force using the same standard formula.
What is the correction factor?
The correction factor adjusts the calculated force. Most users should keep it at 1. Use another value only when your lab has a validated calibration reason.
Why is my RPM warning shown?
The warning appears when the calculated RPM is higher than your entered safe limit. Check the rotor rating, centrifuge limit, tube rating, and protocol before running.
Can I use inches for radius?
Yes. The calculator accepts inches, millimeters, and centimeters. It converts the radius to centimeters internally before applying the formula.
Is this enough for final safety approval?
No. This tool is for conversion and planning. Always confirm values with the rotor manual, centrifuge instructions, sample safety rules, and local lab procedures.