Find the current and power in a circuit from its voltage and resistance.
How the ohm’s law calculator works
Ohm’s law: I = V ÷ R, where I is current in amps, V is voltage in volts and R is resistance in ohms. Power: P = V × I.
Example
A 12 V supply across a 48 Ω resistor drives 0.25 A and dissipates 3 W.
Frequently asked questions
What units does Ohm’s law use?
Volts for voltage, amps for current, ohms for resistance and watts for power.
Does a resistor have a power rating?
Yes. Choose a resistor rated above the calculated power to avoid overheating.
Does this work for AC circuits?
For purely resistive loads, yes, using RMS values. Reactive loads need impedance.