Ohm's Law Calculator
Solve for Volts, Amps, Watts, or Ohms using fundamental electrical theory.
Ohm's Law describes the relationship between Voltage (V), Current (I), and Resistance (R). Enter any two known values, and the calculator will determine the remaining two, plus Power (P).
- Voltage (V): Electrical potential difference, measured in Volts.
- Current (I): Flow of electric charge, measured in Amperes.
- Resistance (R): Opposition to current flow, measured in Ohms.
- Power (P): Rate of energy transfer, measured in Watts.
1Circuit Parameters
Formula Wheel
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Ohm's Law Formula
P = E × I
Electrical Theory Base
Ohm's Law governs the relationship between voltage, current, and resistance in any DC circuit and resistive AC circuit. It is essential for sizing wires, fuses, and understanding circuit behavior.
Frequently Asked Questions
What is "E" in Ohm's Law?
"E" stands for Electromotive Force, which is Voltage. You will often see "V" used interchangeably in modern textbooks.
How do I find Watts if I know Amps and Volts?
Simply multiply them! P (Watts) = E (Volts) × I (Amps). This is the most common calculation for determining circuit load.
Does Ohm's law work for AC circuits?
Yes, but for AC circuits with motors or transformers (conductors/capacitors), you must account for Impedance (Z) and Power Factor, not just pure Resistance (R).