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Power Calculator

Calculate electrical power in watts from voltage and current, or find any one unknown when the other two are known. Covers DC circuits, resistive loads, and component power budgets.

Power & Electrical Relationships

Power (in watts) tells you how much energy is being consumed or dissipated. Use this calculator to work between Power, Voltage, Current, and Resistance. Enter any two known values to solve for the others. Critical for calculating resistor wattage ratings and power supply sizing.

P (Watts)V × II² × REnergyDissipationP = V × I = V² / R = I² × R

Enter any two values to calculate power and other parameters

500 mA = 0.5 A

Enter any two known values to calculate.

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