About this calculator

Ohm's law: V = I × R. Combined with power P = V × I, any two known values let you derive the others. Leave unknowns blank.

Formula: V = I × R, P = V × I

Frequently asked questions

What does the Ohm's Law Calculator do?

Solve for voltage, current, resistance or power given any two of V, I, R or P. Ohm's law: V = I × R. Combined with power P = V × I, any two known values let you derive the others. Leave unknowns blank.

Is the Ohm's Law Calculator free to use?

Yes. Every calculator on Calcora is free, works in your browser without sign-up, and can be embedded on your own website.

How accurate is the Ohm's Law Calculator?

Results are calculated in real time using the formula V = I × R, P = V × I. Treat the output as a well-informed estimate — always cross-check with local regulations, product datasheets, or a qualified electrical professional before committing to a purchase or a job.

What inputs does the Ohm's Law Calculator need?

Enter values for: Voltage (V), Current (A), Resistance (Ω). Sensible defaults are pre-filled where possible so you can start with a single change.

Can I embed the Ohm's Law Calculator on my own website?

Yes — copy the iframe snippet at the bottom of this page, or use the Embed Generator to customise the size. The embedded version stays in sync with the live calculator on Calcora.