Ohm's law states that voltage equals current times resistance, written V = I × R. Power is V × I, so any two of these four quantities determine the other two.

Which units does this use?

Volts for voltage, amps for current, ohms for resistance and watts for power. Convert milliamps to amps by dividing by 1000 before entering.

Is my data sent anywhere?

No. Every calculation runs locally in your browser — nothing is uploaded or stored.

Ohm's Law Calculator

Solve V, I, R and power from any two known values.

Ohm’s law calculator

Ohm’s law links voltage (V), current (I) and resistance (R) with the relationship V = I × R, and electrical power (P) is P = V × I. Given any two of these four quantities, the other two are fully determined.

Pick the pair you know, type the values, and all four results update instantly — entirely in your browser.