Advanced Conversion Calculator
Enter full load amps, voltage, phase, and adjustment options. The result appears above this form after calculation.
Formula Used
Three phase AC: kW = √3 × Voltage × Full Load Amps × Power Factor ÷ 1000
Single phase AC: kW = Voltage × Full Load Amps × Power Factor ÷ 1000
Direct current: kW = Voltage × Full Load Amps ÷ 1000
For several loads, multiply by quantity and demand factor. To estimate usable motor output, multiply input kW by efficiency. Apparent power uses kVA. Reactive power is estimated from kVA and kW.
How to Use This Calculator
- Enter the full load amps from the equipment nameplate.
- Enter the rated voltage. Use line to line voltage for three phase equipment.
- Select the system type. Choose single phase, three phase, or direct current.
- Enter power factor and efficiency when those values are known.
- Add demand factor, quantity, service factor, and safety margin if needed.
- Enter hours, days, energy price, and emissions factor for energy planning.
- Press the calculate button. Read kW, kVA, hp, cost, and range results above the form.
Why Full Load Amps Matter
Full load amps describe the current a motor or device draws at rated load. This value is normally shown on a nameplate. It helps you estimate electrical power when direct watt readings are not available. The value is useful for motors, pumps, fans, compressors, heaters, and many shop machines. It is not the same as locked rotor current. It is also not always the same as running current at a light load.
How kW Is Estimated
Electrical power depends on voltage, current, phase, and power factor. A three phase load uses the square root of three in the equation. A single phase load uses voltage and current directly. Direct current loads do not need power factor. This calculator also lets you include efficiency, demand factor, service factor, quantity, and operating time. These options make the estimate more useful for planning.
Reading the Result
The input kW result shows the electrical power drawn from the supply. The output kW estimate applies efficiency. That value is helpful for motors because some energy becomes heat. Apparent power is shown as kVA. Reactive power is shown as kVAR when power factor is below one. Energy cost is estimated from daily hours, monthly days, and the price per kWh. Emissions are optional and depend on your local grid factor.
Better Data Gives Better Answers
Use nameplate voltage whenever possible. Use line to line voltage for three phase systems. Use a realistic power factor. Many motors are between 0.75 and 0.95 at good load, but the exact value can vary. Efficiency also changes with size, age, speed, and load. Demand factor is useful when several devices do not run at full load at the same time. Quantity multiplies the total load.
Safety and Planning Notes
This tool is for estimating conversion values. It does not replace local electrical code, field testing, or professional design. Breakers, wires, starters, overloads, and disconnects require more checks. Ambient heat, duty cycle, voltage drop, starting current, and installation rules may change the final choice. Still, a clear kW estimate is a strong first step. It helps compare equipment, check generator size, estimate energy cost, and document project assumptions.
Common Mistakes to Avoid
Do not mix phase types. A three phase formula will overstate a single phase result. Do not use starting amps as full load amps. Starting current is short and much higher. Do not ignore power factor on AC loads. Low power factor raises kVA and conductor demand. Do not assume every motor runs at nameplate load. Real machines may cycle, idle, or run below capacity. Use the voltage tolerance option to see a practical range. Then compare the result with measured data when possible. Keep notes with every estimate. They make later audits easier and faster. Small changes in assumptions can move the final load noticeably, especially on large grouped equipment today.
FAQs
What is full load amps?
Full load amps is the rated current drawn by equipment when it delivers its rated output. It is commonly found on a motor nameplate.
How do I calculate kW from full load amps?
Use voltage, current, phase, and power factor. Three phase loads use √3. Single phase loads do not use √3. DC loads do not use power factor.
Why does three phase use √3?
The √3 factor relates line voltage and phase voltage in a balanced three phase system. It lets line voltage and line current estimate total power.
Should I use line voltage or phase voltage?
For a standard three phase calculation, use line to line voltage. For single phase and DC calculations, use the voltage across the load.
What power factor should I enter?
Use the nameplate or measured value when available. If unknown, many loaded motors fall between 0.75 and 0.95, but actual values vary.
Is kW the same as kVA?
No. kW is real power. kVA is apparent power. They are equal only when the power factor is one.
Why include efficiency?
Efficiency estimates usable output power from electrical input power. Motors lose some energy as heat, friction, and magnetic losses.
What does demand factor mean?
Demand factor reduces total connected load when all equipment is not expected to run at full load at the same time.
Can I size wires from this calculator?
No. Use it for conversion estimates only. Wire and breaker sizing need code rules, temperature, voltage drop, duty, and protection checks.
Can I use starting amps?
No. Starting amps are temporary and much higher than full load amps. Use nameplate FLA for normal kW conversion estimates.
Why is my result different from a meter?
Real readings change with load, voltage, power factor, efficiency, and waveform quality. A meter measures actual conditions at that moment.