Volt Ampere Calculator
Volt ampere calculator works out Real power and Apparent power from Voltage, Current and Real power. The default figures on this page give real power of 24 W; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
3 steps
- Given voltage and current.
- Apparent power S = V I = 12 x 2 = 24 VA
- Real power P = 24 W (unity power factor, so P equals S)
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
What the volt ampere calculator calculates
Converts between watts, amps, volts and volt-amps for DC and single-phase AC circuits, including the power factor that separates real from apparent power.
How to use this volt ampere calculator
Enter Voltage, Current, Real power and Power factor. Real power updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Real power, Apparent power and Current.
The method follows Ohm's law: V = I R, and the power relation P = V I, IEC 60050, International Electrotechnical Vocabulary and Apparent power S = V I; real power P = S x power factor.
Research R1734-GT-1: 12 V at 2 A example
With Voltage: 12, Current: 2, the calculator returns Real power: 24, Apparent power: 24. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Real power, Apparent power and Current. The inputs you can vary are Voltage, Current, Real power, Power factor and Solve for.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How to calculate Volt-Ampere?
Converts between watts, amps, volts and volt-amps for DC and single-phase AC circuits, including the power factor that separates real from apparent power. Open “How this is worked out” beside the result to see each step for your own figures.
How many amps is 3000W at 220V?
On the figures this page opens with — voltage 12 V and current 2 A — the real power is 24 W. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
Is 20 amps equal to 120 volts?
Converts between watts, amps, volts and volt-amps for DC and single-phase AC circuits, including the power factor that separates real from apparent power. On the figures this page opens with — voltage 12 V and current 2 A — the real power is 24 W. Put your own figures in their place and the working updates beside the result.
Is 1 ampere equal to A volt?
It needs Voltage, Current, Real power, Power factor and Solve for. Nothing else is required, and the figures stay in your browser.
What information do I need for the volt ampere calculator?
You need Voltage, Current, Real power, Power factor and Solve for. The page opens with default figures that give real power of 24 W, so you can see the scale before entering your own.
What does this volt ampere calculator show?
It shows Real power, Apparent power, Current, Voltage, Equivalent resistance and Solved from, with the working and any warnings for your entries.