Free preliminary sizing tool
Servo RMS torque calculator
Calculate time-weighted RMS torque, peak magnitude and cycle time from torque-and-time segments. Carry the figures into a motor sizing enquiry.
No registration is needed to calculate. Review the method, assumptions and worked example before using the figures.
Enter your calculation inputs
The initial values are an illustrative example. Replace them with your application figures. Calculations run in your browser and do not contact an AI service.
Method and assumptions
T_RMS = √(Σ(T² × t) / Σt)
Enter the total motor-shaft torque for each segment, including any gravity or process load during dwells. Negative torque is allowed and is squared in the thermal calculation. Include the complete repeating cycle. This tool combines supplied torques; it does not calculate them from a mechanism.
Illustrative worked example
Illustrative cycle: 2 Nm for 1 s, 1 Nm for 2 s and 0 Nm for 1 s gives √(6/4) = 1.2247 Nm RMS, 2 Nm peak magnitude and a 4 s cycle. A dwell under load must use the holding torque, not zero.
What the result does not establish
RMS torque is a preliminary duty calculation. It does not check the torque-speed curve, peak duration, drive current, motor losses, cooling or inertia ratio. It does not select or approve a motor.
These are general preliminary calculations, not an engineer-approved design, customer case study or product recommendation. Use the exact manufacturer's ratings and installation conditions for final selection.
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Need help choosing? Build a specification →Other motion calculations
Gearbox ratio, torque and inertia calculator
Estimate output torque and speed through reduction gearing, plus load inertia reflected to the motor. Check assumptions before choosing a gearbox.
Linear actuator force and screw torque calculator
Estimate one upward-motion load case, screw torque, screw speed and mechanical output power. Prepare the figures for an actuator selection enquiry.
Technical resources and checklists · Content and calculation policy
Spec builder
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