Ohm’s Law Calculator
Enter any two electrical values and get the rest calculated instantly using Ohm’s law and the power equation.
How it works
- 1
Enter two known values
Any two of voltage, current, resistance or power.
- 2
Leave the others blank
The calculator solves for the missing values.
- 3
Get all four values
Voltage, current, resistance and power, consistent with each other.
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Frequently asked questions
Any two of voltage, current, resistance or power — leave the other two blank.
The Ohm’s law relationships
Ohm’s law states voltage = current × resistance (V = IR). Power is voltage × current (P = VI). From these two equations, any two known values let you solve for the other two.
For example, with 12 volts and 2 amps, resistance is 6 ohms and power is 24 watts — useful for sizing components, fuses and wiring in basic circuits.