Ohm's Law states V = I × R: the voltage across a conductor equals the current times the resistance. Power is P = V × I = I²R = V²/R.

Which units should I use?

Volts (V), amperes (A) and ohms (Ω). Power comes out in watts (W). The math is unit-agnostic as long as the three are consistent.

Can I solve for resistance?

Yes — leave the resistance field empty and the calculator returns R = V / I.

Leave one blank to solve for it. If all three are filled, the calculator uses V and I (or R and I) to verify.

No. Everything is computed locally in your browser.

Solve V = I × R for any one variable — voltage, current or resistance.

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