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Calculate voltage, current, resistance, and power using Ohm's Law for DC and basic AC electrical circuits with instant engineering calculations.
LED Circuit
Enter voltage and current to calculate resistance and power for resistor sizing.
Power Check
Enter voltage and resistance to find circuit current and wattage load.
These two colorful original SVG diagrams show the Ohm’s Law triangle and a simple resistor circuit.
This calculator solves the missing electrical values when any two values are known.
Ohm’s Law is one of the most important formulas in electronics and electrical work. It connects voltage, current and resistance, while power formulas help estimate heat and load rating. This calculator is useful for resistor sizing, LED circuits, power dissipation checks, sensor circuits, battery-powered projects and general electronics troubleshooting.
Ohm’s Law states that voltage equals current multiplied by resistance.
Yes. Enter any two valid values and the calculator fills the remaining values.
Using mA instead of A or kΩ instead of Ω changes the numeric scale, so unit selection matters.
Power is the rate of electrical energy conversion, calculated in watts.
Yes. The calculated power helps choose a safe resistor wattage rating.
The calculator uses the first matching formula path based on available values.
It is best for basic DC and resistive AC calculations.
Ohm's Law Calculator is a free online calculator tool. Use it to get instant, accurate results for your electronics calculations.