Motor torque equations
Shaft output power and rotational speed define steady operating torque.
T(N·m) = 9550 × Pout(kW)/n(rpm)Pout = Pin × ηT(lb-ft) = 5252 × Pout(hp)/n(rpm)where:
- T
- Shaft torque
- Pout
- Mechanical shaft output power
- n
- Shaft speed[rpm]
Starting and breakdown torque require the motor torque-speed curve.
How to use the Motor Torque Calculator
Calculate motor shaft torque, output power, input power, angular speed, and lb-ft from kW or hp, rotational speed, and efficiency. Start by choosing the operating mode, then enter values from nameplates, measurements, or project documents in the units shown. The result updates immediately and keeps intermediate quantities visible for review.
- Confirm the system and calculation mode.
- Enter measured or manufacturer-rated values.
- Review the primary result and intermediate metrics.
- Continue with the related protection or equipment-selection checks.
Calculation method and validation
The equations and symbol definitions above show the complete calculation basis. Inputs are checked before calculation so zero, negative, incompatible, or physically impossible combinations are flagged instead of silently producing a misleading result.
How to interpret the result
Use the main result as a starting value and read every supporting metric. Entered speed is shaft speed Torque is steady operating torque at the entered power 1 hp = 0.7457 kW A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- Entered speed is shaft speed
- Torque is steady operating torque at the entered power
- 1 hp = 0.7457 kW
Selection limits and next checks
Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions. Starting, breakdown, and accelerating torque require the motor torque-speed curve. Gearbox losses and driven-load torque are outside this calculation. Compare the output with the current applicable standard, local rules, exact VIOX product datasheet, environmental conditions, protection coordination, and the engineer's project requirements before procurement or installation.
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Assumptions
- Entered speed is shaft speed
- Torque is steady operating torque at the entered power
- 1 hp = 0.7457 kW
Important Warnings
- Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions.
- Starting, breakdown, and accelerating torque require the motor torque-speed curve.
- Gearbox losses and driven-load torque are outside this calculation.