Watts = Volts × Amps
Watts = Volts × Amps × Power Factor
Watts = Joules ÷ Seconds
Watts = Volts² ÷ Ohms
Watts = Amps² × Ohms
Find voltage and current
Multiply voltage by current
Use power factor for AC circuits if needed
Use resistance formulas if voltage or current is unknown
Check units before calculating