Centrifugal Force Calculator

Related Calculators

Calculation mode: The main choice between a physics answer in newtons and a lab answer in x g.

Centrifugal force: The outward apparent force noticed in a rotating frame of reference.[1]

Centripetal force: The inward force needed to keep an object moving in a circle; for steady circular motion, its magnitude matches the centrifugal-force magnitude used here.[4]

Tangential speed (m/s): The linear speed along the circular path.

Angular speed (rad/s): How fast something turns, measured in radians each second.

Radius: The distance from the axis of rotation to the object or sample location.

Relative centrifugal force (x g): A lab-style measure that compares centrifugal acceleration with the acceleration due to gravity, rather than giving force in newtons.

Method note: A short reminder of which formula, speed type, and unit path the calculator used for your answer.

Mistake: Using Relative centrifugal force (x g) as if it were the same as Centrifugal force in N.
Fix: Use Calculation mode to keep the two ideas separate. Physics mode gives Centrifugal force in N, while Lab RCF mode gives Relative centrifugal force in x g.

Mistake: Entering Angular speed (rad/s) when Known speed type is set to tangential speed, or entering Tangential speed (m/s) when it is set to angular speed.
Fix: Match the visible input to the selected Known speed type . Only the shown speed field is used.

Mistake: Typing the wrong unit into Radius (m) after changing Physics radius unit in Advanced options.
Fix: Make sure the number in Radius (m) is entered in the currently selected physics radius unit. If you switch from m to cm or ft, recheck the value before calculating.

Mistake: Using diameter instead of radius for Radius (m) or Rotor radius (cm) .
Fix: Enter the distance from the center of rotation to the object or sample, not the full width across the circle.

Mistake: Guessing the wrong sample position for Rotor radius (cm) in Lab RCF mode.
Fix: Use the radius definition from your rotor manual if it gives a max, average, or effective radius, and keep that same definition when reading Relative centrifugal force or Rotor speed .

Mistake: Solving for Tangential speed , Angular speed , or Rotor speed with impossible or invalid inputs such as zero radius or a negative force value.
Fix: Enter a positive Radius (m) or Rotor radius (cm) , keep Mass (kg) nonnegative, and use nonnegative Rotor speed (RPM) or Relative centrifugal force (x g) .

• The calculator reports ideal steady circular-motion values from the selected formula. Real systems can differ because of friction, wobble, changing speed, drag, or uneven mass distribution.
• In Physics force mode, the result is a magnitude. It does not track direction, vector components, or changing motion over time.
• Physics results depend strongly on speed because speed is squared. Small speed input errors can cause much larger force errors.
• Lab RCF results depend on the chosen Rotor radius (cm). Using max, average, bottom-of-tube, or effective radius can change the answer.
• The lab mode gives Relative centrifugal force (x g), not force in newtons. Do not compare those outputs as if they were the same unit.
• Radius must be greater than 0 in all modes. Negative RPM, negative RCF, or negative mass are invalid for this calculator.
• If you force decimal display for extremely large or very small values, the calculator may still switch to scientific notation to avoid unreadable output.

Physics mode

In Physics force mode, the calculator uses one of two standard circular-motion formulas depending on Known speed type. Many classes describe the inward centripetal force, while this tool reports the matching outward apparent centrifugal-force magnitude for a rotating frame.[1][4]

F = m * v^2 / r

F = m * omega^2 * r

v = omega * r

a = v^2 / r = omega^2 * r

Here, F is force in N, m is mass in kg, v is tangential speed in m/s, omega is angular speed in rad/s, r is radius in m, and a is acceleration magnitude in m/s^2.

If you solve for a different quantity, the calculator rearranges the same formula. For example, when solving for tangential speed, it uses v = sqrt(F * r / m). When solving for radius from tangential-speed data, it uses r = m * v^2 / F. Inputs that are hidden for the active choice are ignored so they cannot change the result by accident.

Mini example: if Mass (kg) = 2, Tangential speed (m/s) = 6, and Radius (m) = 3, then the calculator finds F = 2 * 6^2 / 3 = 24 N and a = 6^2 / 3 = 12 m/s^2.

Lab RCF mode

In Lab RCF mode, the calculator uses the standard centrifuge relationship between RPM, radius in centimeters, and relative centrifugal force.

RCF = 1.118e-5 * r_cm * RPM^2

RPM = sqrt(RCF / (1.118e-5 * r_cm))

omega = RPM * 2 * pi / 60

Here, r_cm is Rotor radius (cm), RCF is reported in x g, and RPM is revolutions per minute. The extra angular-speed output helps connect lab notation to physics notation.

Mini example: if Rotor speed (RPM) = 5000 and Rotor radius (cm) = 10, then RCF = 1.118e-5 * 10 * 5000^2 = 2795 x g. The matching angular speed is 5000 * 2 * pi / 60 = 523.6 rad/s.

Units and conversions

The calculator converts any selected tangential-speed unit to m/s before using the physics formulas, and it converts the selected physics radius unit to meters before calculation. Lab radius stays in centimeters because the RCF constant is defined for cm and RPM in this equation.

Output interpretation

A higher Centrifugal force or Centrifugal acceleration magnitude means stronger circular-motion loading. In physics mode, changing speed usually has the biggest effect because the speed term is squared. In lab mode, doubling RPM makes RCF four times larger, while doubling rotor radius makes RCF two times larger.

Assumptions used

This tool assumes steady circular motion, positive radius, and valid numeric inputs. It does not model changing speed, slipping, vibration, fluid motion inside a tube, or equipment-specific correction factors. Radius choice in Lab RCF mode must match the rotor definition you intend to use, because a different radius changes the result.