Use this Ohm’s law calculator to find the voltage, current, resistance or power in a circuit. Fill in any two of the values, and it calculates the other two.
Ohm’s law tells you how voltage, current and resistance are connected. Together with the formula for power, it gives you everything you need:
Fill in any two values. The other two are calculated.
- Voltage
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- Current
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- Resistance
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- Power
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How to Use It
Type in the two values you know, like the battery voltage and the resistor value. The two you didn’t type in are filled in for you, in the unit that suits them best. If you type a value into one of those, it’s used instead, and the calculator works out the others from your two latest values.
The power tells you how much the resistor heats up. Pick a resistor rated for at least twice that, so it doesn’t run hot.
Want to learn more? Check out the Ohm’s law tutorial, or learn about series and parallel circuits.