Ohm's Law Calculator
Enter any two known values to calculate voltage, current, resistance, and power with unit conversion.
Lock two fields with known values; the other two are calculated automatically.
Ohm's law basics
Ohm's law relates voltage (V), current (I), and resistance (R): V = I × R. Power (P) is the rate of energy transfer: P = V × I. Given any two quantities, the others can be derived — essential for sizing resistors, checking LED current, and debugging circuits.
