Advanced Electric Power Calculator

Calculator Form

Calculation Method

Voltage

Current

Resistance

Power Factor

Output Power Unit

Runtime

Tariff per kWh

Notes

Use power factor only for AC modes. Runtime and tariff are optional.

Reset Form

Example Data Table

Scenario	Inputs	Formula	Result
DC Device	12 V, 5 A	P = V × I	60 W
Heater Element	230 V, 46 Ω	P = V² / R	1,150 W
Resistive Branch	8 A, 10 Ω	P = I² × R	640 W
Single Phase Motor	230 V, 8 A, PF 0.92	P = V × I × PF	1,692.8 W
Three Phase Load	400 V, 20 A, PF 0.9	P = √3 × V × I × PF	12,470.8 W

Formula Used

Electric power shows how quickly electrical energy is converted or transferred. The basic direct current equation is power equals voltage multiplied by current. When current is not known, the same power can be found with voltage squared divided by resistance or current squared multiplied by resistance.

For alternating current circuits, real power depends on power factor. Single phase real power equals voltage multiplied by current multiplied by power factor. Three phase real power equals square root of three multiplied by line voltage, line current, and power factor. Apparent power is measured in volt amperes, while reactive power is measured in VAR.

This calculator also estimates energy use from runtime. Energy in watt hours equals power in watts multiplied by time in hours. Dividing watt hours by one thousand gives kilowatt hours. Estimated operating cost equals kilowatt hours multiplied by your tariff rate.

How to Use This Calculator

Select the calculation method that matches your known electrical values.
Enter voltage, current, resistance, or power factor as required.
Choose the preferred input units for each field.
Pick the output unit for the power result.
Add runtime to estimate watt hours and kilowatt hours.
Enter a tariff value to estimate operating cost.
Press Calculate Power to show the result above the form.
Use Download CSV or Download PDF when you need a report.

FAQs

1. What is electric power?

Electric power is the rate at which electrical energy is transferred or converted. It is commonly measured in watts, kilowatts, or megawatts depending on application size.

2. When should I use P = V × I?

Use that equation when voltage and current are already known. It works directly for DC circuits and for resistive loads where voltage and current are in phase.

3. Why is power factor important in AC systems?

Power factor shows how much apparent power becomes real working power. A lower factor means more current is required for the same useful output.

4. What is the difference between real, apparent, and reactive power?

Real power performs useful work. Apparent power is the total electrical demand. Reactive power supports magnetic and electric fields in AC equipment.

5. Can this calculator estimate energy consumption?

Yes. Enter runtime and the calculator converts power into watt hours and kilowatt hours, which helps estimate daily or periodic energy use.

6. Can I use this for three phase systems?

Yes. Choose the three phase AC mode, then enter line voltage, line current, and power factor. The calculator applies the standard three phase real power formula.

7. Why do voltage and resistance also produce current results?

Those values allow the calculator to derive current using Ohm’s law. That derived current is then used to support the final power calculation summary.

8. What unit should I choose for the result?

Choose watts for small devices, kilowatts for larger loads, megawatts for plant level demand, and horsepower when comparing with mechanical output ratings.