Enter any two of voltage, current, resistance, and power to solve for the other two.
Ohm's Law relates voltage, current, and resistance: V = I × R. Combined with the power equation P = V × I, any two of the four quantities are enough to solve for the other two — the calculator picks whichever pair of equations fits the two values you provided.
These equations hold exactly for simple resistive circuits (no capacitors or inductors), under both DC and AC conditions. Reactive components introduce phase differences between voltage and current that this calculator doesn't account for.
Whichever two you actually know. Fill in any two fields (in any combination) and leave the other two blank.
No — our Resistor Calculator reads a resistor's color bands to find its resistance value, rather than working from voltage, current, and power.
Pick another tool to jump straight to it.