Ohm's Law Calculator

Enter any two values to calculate the others.

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V I × R

Fill in exactly two fields, leave the others empty.

V
A
Ω
W
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Frequently Asked Questions

What is Ohm's Law? +
Ohm's Law states that voltage (V) equals current (I) times resistance (R), written as V = I x R. Combined with the power equation P = V x I, you can derive any two electrical values from the other two.
How do I use the Ohm's Law triangle? +
Cover the value you want to find. If the remaining two values are side by side, multiply them. If one is above the other, divide the top by the bottom. For example, cover V and you see I x R, so V = I x R.
What units are used in Ohm's Law? +
Voltage is measured in volts (V), current in amperes/amps (A), resistance in ohms (the Greek letter omega), and power in watts (W). Using consistent SI units ensures accurate calculations.
Can Ohm's Law be used for AC circuits? +
Ohm's Law applies to AC circuits, but you must use impedance instead of resistance. Impedance includes both resistance and reactance from capacitors and inductors, and calculations involve complex numbers.
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