Ohm's Law Calculator

What this calculator does

Ohm's law links voltage, current and resistance. Add any two values and the calculator fills in the rest, including power where possible.

Formula used

Voltage equals current multiplied by resistance. Power equals voltage multiplied by current.

How to read the result

Use the result as a formula check. Real electrical systems can involve tolerance, heat, AC behaviour, reactive components and safety rules that this simple calculator does not model.

Assumptions

• Assumes a simple DC circuit.
• Requires at least two values.
• Does not replace electrical safety guidance.

Sources and checks

This calculator uses a standard public formula. Where rules or thresholds can change, source links are listed on the relevant page.

Frequently asked questions