Volts alone can’t be used to figure out how many watts there are. Amperage is also important.
To find out how many watts are in 120 volts, you need to know the formula that relates power (P) in watts to volts (V) and current (I) in amps. Power equals volts times amps, or P = V x I. This is the formula for this relationship.
Using the formula, the answer to the question of how many watts are in 120 volts that deliver a current of 2 amps is 240 watts.
The units used to measure electricity are watts, amps, volts, and ohms.