Wattage

The U.S. Energy Information Administration explains that electricity is measured in units of power called watts, and that one kilowatt equals 1,000 watts. A small bulb and a space heater draw power at very different rates. Watts tie together voltage and amperage: volts times amps equals watts.

Watts show the rate. The bill counts kilowatt-hours, which are watts used over time. Adding up the wattage on one circuit helps show when it may overload. Circuits that trip often need a licensed electrician. See why a breaker keeps tripping.