Electrical Power Calculator Formula

Understand the math behind the electrical power calculator. Each variable explained with a worked example.

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Formulas Used

Power (V*I)

power_vi = voltage * current

Power (I²R)

power_i2r = pow(current, 2) * resistance

Power (V²/R)

power_v2r = pow(voltage, 2) / resistance

Variables

VariableDescriptionDefault
voltageVoltage(V)120
currentCurrent(A)5
resistanceResistance(Ω)24

How It Works

Electrical Power

Electrical power is the rate of energy transfer in an electric circuit.

Three Equivalent Forms

P = V * I (voltage times current)

P = I² * R (current squared times resistance)

P = V² / R (voltage squared divided by resistance)

All three yield the same result when V, I, and R satisfy Ohm's law.

Worked Example

A 120 V circuit drawing 5 A through a 24 ohm load.

voltage = 120current = 5resistance = 24
  1. 01P = V * I = 120 * 5 = 600 W
  2. 02P = I² * R = 25 * 24 = 600 W
  3. 03P = V² / R = 14400 / 24 = 600 W

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