Ohm's Law: Voltage, current, resistance and power in a circuit. This free calculator solves for Voltage, current, resistance, power and shows every step.
Ohm's law is the workhorse of circuit analysis: voltage drives current through resistance. Combined with the power relationships, knowing any two of voltage, current and resistance yields all four quantities including power.
A 12 V supply across a 4 Ω resistor. I = V/R = 12/4 = 3 A; P = V·I = 12·3 = 36 W.
Circuit and electronics design, choosing fuses and wire gauges, power-supply sizing, LED resistor selection, fault-finding.
Ohm's Law uses the formula V = I·R · P = I·V. Voltage, current, resistance and power in a circuit.
Choose which variable to solve for, enter the values you know (in any supported unit), and the calculator substitutes them into V = I·R · P = I·V and shows every step of the working. It can solve for Voltage, current, resistance, power.
Yes — every Physics Fundamentals calculator is completely free, with no login, no ads and no usage limits.