An Ohm's Law calculator computes voltage (V), current (I), resistance (R), and power (P) for an electrical circuit.
About this calculator
An Ohm's Law calculator computes voltage (V), current (I), resistance (R), and power (P) for an electrical circuit. Ohm's Law states that voltage equals current times resistance: V = I × R. Combined with the power formula (P = V × I), you can find any of the four quantities from any two others.
Ohm's Law is a basic relationship in electronics and electrical engineering. It matters for anyone working with circuits, electronics projects, or electrical systems.
Common uses
- Calculate current draw of an electrical device from voltage and resistance
- Find the required resistance for an LED circuit
- Determine power consumption from voltage and current
- Verify electrical component ratings in circuit design
Frequently asked questions
What is Ohm's Law?
Ohm's Law: V = I × R, where V is voltage in volts, I is current in amperes, and R is resistance in ohms. Derived formulas: I = V/R (current), R = V/I (resistance), and Power P = V × I = I² × R = V²/R.
What is the difference between AC and DC for Ohm's Law?
Ohm's Law applies directly to DC (direct current) circuits with purely resistive loads. For AC circuits, the relationship is modified by impedance (Z), which includes resistance plus reactance from capacitors and inductors: V = I × Z. For purely resistive AC circuits, Ohm's Law applies as-is.