How many values do I need?

Enter any two compatible values among voltage, current, resistance and power.

Does Ohm's law work for AC?

For pure resistive or equivalent RMS calculations, yes. Reactive AC circuits need impedance and phase-aware analysis.

Some combinations represent an open circuit, short circuit or contradictory data, so the ideal model cannot return all four values safely.

Calculate voltage, current, resistance or power from any two known electrical values.

Enter exactly two known quantities or a consistent set of three to four

Voltage

Current

Resistance

Power

Scenarios:

Ohm's law search intent expects a four-value solver: enter any valid pair and calculate the remaining electrical quantities.

V = I R

V is voltage, I current and R resistance.

P = V I

P is electric power for a DC or resistive equivalent circuit.

Ideal circuit assumption

The calculator uses an ideal Ohm's law model. Real sources, wires, protection devices, heating and AC phase effects can change results.

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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