Basic Concepts

• The electricity used by household appliances on a practical basis is measured in terms of watts. This statistic indicates how much power the appliance uses during an hour's operation. An appliance's wattage rating, along with its voltage and amperage ratings, are usually available on the same label that bears the Underwriters Laboratories stamp.
  
  

Heater Power Use

• According to the U.S. Department of Energy, portable heaters in the U.S. typically consume between 750 and 1,500 watts. A small space heater might consume at the bottom of that range, while a large, oil-filled radiator-style heater might consume at the top of that range. Also, some heaters have multiple power settings.
  
  

Relative Comparison

• Portable heaters are power-hungry appliances compared to similar devices. Those appliances with similar wattage ratings, such as hair dryers, microwaves and toasters, are rarely used for more than several minutes at a time. Most appliances that are left on for hours at a time, such as personal computers and televisions, have much lower wattage ratings.