Ohm's Law Calculator
Find voltage and power from current and resistance.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
Ohm's Law Calculator
How to use this tool
- Enter the current in amps and the resistance in ohms.
- Press Generate to see the voltage and the power.
- Change either number to compare different resistors or currents.
Worked example
With a current of 2 A through a 12 ohm resistor, voltage is 2 x 12 = 24 V and power is 24 x 2 = 48 W.
What this tool does not do / Limits
This uses the ideal Ohm's law for a fixed resistor on direct current. It ignores temperature change, resistor tolerance and alternating-current effects, and it is an estimate, not a substitute for a component datasheet or a qualified electrician.
Frequently asked questions
What if I know voltage and resistance instead?
Rearrange the same law: current equals voltage divided by resistance, then power equals voltage times that current.
Why is power voltage times current?
Power is the rate energy is delivered, and for a resistor it equals the voltage across it multiplied by the current through it.
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