Ohm's Law Calculator
Calculate Voltage (V), Current (I), Resistance (R), and Power (P). Enter any two known values to find the others instantly.
About Ohm's Law
Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points.
V = I × R
- V = Voltage in Volts (V)
- I = Current in Amps (A)
- R = Resistance in Ohms (Ω)
Power Law (Watt's Law)
Electrical power is the rate at which electrical energy is transferred or used.
P = V × I
- P = Power in Watts (W)
By combining these two laws, we can derive formulas to find any value if we know two others. For example, knowing Resistance and Current allows us to find Power using P = I² × R.
? Frequently Asked Questions
'I' stands for Intensity of Current (French: Intensité de Courant). It represents the flow of electric charge, measured in Amperes (Amps).
This calculator applies strictly to DC circuits or purely resistive AC circuits. For AC circuits with inductance or capacitance (motors, transformers), you need to account for Impedance (Z) and Phase Angle.
If Current is 0 while Voltage is greater than 0, Resistance must be infinite (an open circuit). If you get an error, check your inputs.