Category: Calculators
Ohm's Law Calculator
Solve for voltage, current, resistance or power
Enter any two of voltage, current and resistance to calculate the third value plus power, using Ohm's law and the power law.
Resistance (Ω)6 Ω
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What this tool does
Ohm's law (V = IR) relates voltage, current and resistance in a circuit; power (P = VI) follows from the same two values. Pick which pair of quantities you know, and the missing value and power are calculated instantly in your browser.
How to use it
- Choose which two quantities you already know.
- Enter their values.
- Read the calculated value and power underneath.
Privacy
This tool runs entirely in your browser. Your input is never uploaded, stored or shared — closing the tab removes it.
Frequently asked questions
- What is Ohm's law?
- Ohm's law states that voltage equals current multiplied by resistance (V = IR). Rearranged, current is voltage divided by resistance (I = V/R), and resistance is voltage divided by current (R = V/I).
- How is power calculated?
- Electrical power in watts is voltage multiplied by current (P = VI). This calculator derives it automatically from whichever two values you enter.
- Does this account for AC circuits with reactance?
- No. This calculator uses the basic DC form of Ohm's law for resistive circuits. AC circuits with capacitors or inductors involve impedance and phase, which this tool does not model.