Ohm's Law Calculator

Enter any two of the four electrical values — Voltage (V), Current (I), Resistance (R), and Power (P) — and the calculator will solve for the remaining two using V=IR and P=IV.

V = I × R | P = I × V | P = I² × R | P = V²/R

Enter exactly 2 values, leave the other 2 blank.

Voltage — V (Volts)

Current — I (Amperes)

Resistance — R (Ohms Ω)

Power — P (Watts)

Ohm's Law is the foundation of circuit analysis. V=IR means doubling resistance halves current. P=IV means power scales with both voltage and current — doubling both quadruples power dissipation.