Free · Electrical power
Supply Power and Mechanical Output Estimate
Estimate DC, single-phase or balanced three-phase input power and an efficiency-scaled mechanical output using declared rounded factors.
- Formula & worked example
- Private in your browser
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Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
Private by default
Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.
Formula and method
A 230 V, 10 A single-phase supply at power factor 0.8 gives 2.3 kVA apparent power and 1.84 kW active input power.
S = c V I / 1000; P = S PF for AC and S for DC; mechanical hp = 1000 P efficiency / 746
Worked example
Enter these known values and leave the other values blank.
- Power supply type
- AC single phase
- Current
- 10 A
- Voltage
- 230 V
- Power factor
- 0.8
- Efficiency (η)
- 90 %
- Apparent power
- 2.3 kVA
- Power
- 1.84 kW
- Approximate mechanical output (746 W/hp)
- 2.22 hp
Assumptions and limitations
- For AC, enter RMS voltage and current. Three-phase mode assumes a balanced system and uses line-to-line voltage and line current. DC omits the power factor.
- The captured three-phase coefficient is the rounded 1.732 approximation to sqrt(3); the horsepower conversion uses a rounded 746 W/hp. Results are approximate engineering estimates rather than precise unit metrology.
- The horsepower relationship scales electrical INPUT power by efficiency, describing mechanical OUTPUT of a motor. It does not calculate a generator prime mover rating, which would require dividing electrical output by generator efficiency.
- Efficiency must be nonnegative and below 100 percent under the captured domain. The model excludes the ideal 100 percent endpoint. It does not include overload margin, starting current, conductor sizing or protection requirements.
Common questions
Which voltage belongs in three-phase mode?
Use line-to-line RMS voltage for a balanced three-phase system. The captured model uses 1.732 as a rounded square-root-of-three factor.
Does horsepower describe generator input?
No. This efficiency multiplication estimates mechanical output from electrical input, as in a motor. A generator prime mover requirement uses the opposite energy direction.
References
- Fluke power analyzer: active power, apparent power and power factor
- Calculation definition and unit reference
The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.