Calculate electrical power from any two of voltage, current and resistance.
All three power forms follow from Ohm’s law and give the same answer for a consistent set of values. Comparing them is a quick check that the measured voltage, current and resistance agree. The I²R form is the one that matters for losses, because it shows heating rises with the square of current — the reason transmission uses high voltage.
Electrical Power
P = V I = I² R = V² ÷ R
P = V I = I² R = V² ÷ R All three power forms follow from Ohm’s law and give the same answer for a consistent set of values. Comparing them is a quick check that the measured voltage, current and resistance agree.
The I²R form is the one that matters for losses, because it shows heating rises with the square of current — the reason transmission uses high voltage.
This calculator takes 3 inputs: Voltage, Current, Resistance. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.