Voltage to Watts Calculator
Voltage to Watts Calculator
Calculating watts from voltage and current lets you determine the power consumption of any electrical circuit or device. The formula varies slightly depending on whether the circuit is DC or AC.
Conversion Formula
DC: W = V × A. AC single phase: W = V × A × PF. AC three phase: W = V × A × PF × 1.732. For purely resistive loads, PF = 1 and the AC formula reduces to the DC formula.
Step-by-Step Examples
120V, 10A, DC = 1200 W
120 × 10 = 1200 watts
240V, 15A, AC 1ph, PF=0.95 = 3420 W
240 × 15 × 0.95 = 3420 watts
Frequently Asked Questions
How do I calculate watts from voltage and current?
For DC circuits, multiply volts by amps: W = V × A. For AC circuits, also multiply by the power factor. Three phase adds another factor of √3 (approximately 1.732).
What is the power factor for household appliances?
Simple resistive loads (heaters, incandescent bulbs) have PF = 1.0. Motors, compressors, and fluorescent lights typically range from 0.7 to 0.95. Check the appliance nameplate for the stated power factor.
Why does three phase power use √3 in the formula?
In a three phase system, three conductors carry power shifted 120 degrees apart. The √3 factor (≈1.732) accounts for the geometric relationship between the line voltage and phase voltage in a balanced three phase circuit.