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RK
Rojony Khatun
Last updated: Jun 3, 2026

Motor Efficiency Calculator

Quickly compute motor efficiency from input power, output power, voltage, current, and PF. Get losses and helpful formulas for single- or three-phase motors.

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Motor Efficiency Calculator

Quickly compute motor efficiency from input power, output power, voltage, current, and PF. Get losses and helpful formulas for single- or three-phase motors.

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induction motor efficiency tool

Motor efficiency = output power/ input power x 100. Measuring and calculating the referring input power of voltage, current, and power factor, measuring output as shaft power (kW or hp). Losses = Input -- Output.

Formula & Table Summary:

  • η(%) = (Pout/Pin) × 100
  • 3φ: Pin = √3 × VL × IL × PF
  • 1φ: Pin = V × I × PF
  • Pout = (2π × N × τ)/60
  • 1 hp = 0.746 kW; Ploss = Pin − Pout

Input: V, I, PF (+hp or τ & rpm) → Pin. Output: kW (or hp) → Pout. Returns η% and losses with validation if Pout > Pin.

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three phase motor efficiency

Use this motor efficiency calculator to estimate the usefulness of a motor to convert electrical energy to mechanical energy. Input power can be obtained by entering voltage, current, and power factor in single or three-phase loads. Insert regulated output power (kW or hp), or torque and speed, and the tool gives the efficiency(% ) and losses (kW). It is a recommended method to size motors to determine equivalent solution and to detect excessively high losses in the field. The calculator does synoptic calculations (hp kW), will calculate the input of three-phase as V I 3P F, and it highlights inputs as greater than their outputs. Apply to induction motors, pumps, fans, and conveyors. Compare operating results against nominal nameplate data to determine whether a motor is operating close to its efficiency curve. The short and sweet form supply sheet and sample data table allow technicians to check readings and record audits. Set up to target low competition keywords, this page will create rankings on certain calculator-related queries and provide a reader with precise calculations made in an engineer-friendly manner.

motor performance table

Case Phase V (V) I (A) PF Pin (kW) Pout (kW) η (%) Losses (kW)
1 400 32 0.86 19.1 16.5 86.4 2.6
2 230 18 0.90 3.73 3.10 83.1 0.63
3 415 48 0.82 28.3 24.0 84.8 4.3
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Frequently Asked Questions - Motor Efficiency Calculator:

It is the ratio of shaft output power to electrical input power, expressed as a percentage.
Use Pin = √3 × VL × IL × PF (kW if VL in kV).
Yes. Convert with 1 hp=0.746 kW or enter hp directly if supported.
Measurement error—check instruments, PF, wiring, and units.
Indirectly. Load and slip change with speed, affecting losses and efficiency.
Use the real power factor at the motor terminals from a meter or VFD readout.
Use torque sensor or infer from pump/fan curves and rpm; otherwise use nameplate rating cautiously.
Yes, they increase losses and reduce efficiency; fix supply quality issues first.
Not always—field efficiency varies with load, temperature, and supply conditions.
Premium motors often exceed 90% at rated load; smaller or lightly loaded motors are lower.
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