Electrical Power Calculator

Use this calculator for quick DC and basic electrical-power checks when two of power, voltage, and current are already known.

Inputs

Enter your values

Keep learning

Use the calculator, then keep the full method close.

This topic also has a deeper guide and a printable reference pack, so you can move from the live answer into the method, assumptions, and worked examples without leaving the topic cluster.

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Related guides

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Ohm's Law and Core Circuit Relationships

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Downloadable references

Revision GuideElectrical & Electronics

Ohm's Law and Electrical Fundamentals Reference Guide

A fuller printable revision guide for voltage, current, resistance, power, and conductance with unit discipline, worked examples, and quick bench-side checks.

Printable PDFOpen download

Input guide

These are the main values the calculator uses. Keep the units consistent and, where relevant, match the assumptions explained in the related guide.

Input

Power

Unit: W

Use the load or output power for the same operating point as the voltage and current values.

Input

Voltage

Unit: V

Enter the voltage at the load or supply point where power is being evaluated.

Input

Current

Unit: A

Use the current drawn at the same operating point as the power and voltage values.

Formulae

P = V x I

V = P / I

I = P / V

When to use this calculator

Use this page when the main question is how much power a circuit uses, or what voltage or current is implied by the other two power-related values.

How to read the result

The main result shows the missing electrical quantity first. Supporting figures repeat the known inputs so the operating point stays visible while you compare scenarios.

Worked example

If a 12 V supply feeds a load drawing 5 A, the electrical power is 60 W.

If a device consumes 60 W at 12 V, the implied current is 5 A.

Assumptions and limits

This page is intended for straightforward electrical power relationships. It does not model power factor, reactive AC behaviour, duty cycle, or efficiency losses unless you handle those separately.

Common questions

How is this different from the Ohm's Law page?

Ohm's Law focuses on voltage, current, and resistance. This page focuses on power, voltage, and current, which is often the more direct way to size supplies, loads, or dissipation.

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