Electrical
Watt Calculator
Calculate power in watts from voltage and current, for single-phase or three-phase circuits.
Result
Electrical work is life-safety work governed by the NEC or your local code, and must be designed and installed by a licensed electrician. Conductor and overcurrent sizing depends on ambient temperature, conductor bundling, termination ratings, continuous-load rules and more. This is an educational estimate and must never be used as the basis for an installation.
Get a Free Business AuditQuestions
About this calculator
What is the difference between watts and VA?
Volt-amps is apparent power. Everything the supply must deliver. Watts is real power that does work. Power factor is the ratio between them, and it is 1 only for purely resistive loads.
Why is three-phase multiplied by √3?
Because the three phases are 120 degrees apart, so their combined contribution is √3 (about 1.732) times the single-phase product rather than three times.
The formula
single phase: W = V × A × PF; three phase: W = V × A × √3 × PF
Put this calculator on your site
Free to embed. Paste this where you want it to appear. It stays up to date automatically because it loads from BDEVY.
Please keep the attribution line. It is the only thing we ask in return.
Keep going
Related calculators
Amp Calculator
Convert watts to amps for single-phase or three-phase circuits, and check it against a breaker..
Open calculatorkWh Calculator
Convert an appliance's wattage and run time into kilowatt-hours of energy use..
Open calculatorOhm's Law Calculator
Solve any part of Ohm's law (voltage, current, resistance or power) from the two values you know..
Open calculatorEstimating is the easy part
The jobs you never hear about cost more than the ones you mis-measure. BDEVY builds the marketing, systems and automation that bring them in.