Ohms Law Calculator
Work out voltage, current or resistance from the other two using Ohm's law.
The foundation of circuits
Ohm's law ties together the three basic quantities of an electrical circuit — voltage, current and resistance — so that given any two, the third follows. This calculates whichever you need, the everyday tool for anyone working with electronics, from a hobby project to understanding a circuit.
Enter two of voltage, current and resistance to get the third.
Why it underpins everything
Ohm's law is the single most useful relationship in basic electronics because so much follows from it: sizing a resistor to limit current, working out how much current a component will draw, checking a voltage. Adding power to the picture lets you also work out heat and wattage, important for not overloading a component. Whether you are protecting an LED, reading a circuit, or troubleshooting a high current draw, this relationship is where the reasoning starts.
Ohms Law Calculator FAQ
What does Ohm's law relate?
Voltage, current and resistance — given any two, it gives the third, the foundation of understanding any electrical circuit.
What is it used for in practice?
Sizing resistors, working out a component's current draw, and checking voltages — the everyday reasoning of electronics.
Is anything uploaded?
No. The calculation happens in your browser.