Calculate Energy Consumption

Calculate Appliance Operating Costs

  • Convert wattage to kilowatts
    An appliance's wattage is usually stamped on a metal plate (name plate) or in the plastic covering on the back or bottom of the appliance.

Divide wattage by 1000.

/ 1000


  • Calculate the kilowatt-hours (KWH) the appliance uses
    Some appliances, such as refrigerators, water heaters, air conditioners, dryers, skillets, irons and ovens, are controlled by thermostats that cycle on and off automatically, using energy only when the heating element(s) or motor(s) is on.  To figure their energy use, you have to estimate the amount of time they are actually at full load.

Multiply the kilowatts by the number of hours (Convert time to whole numbers: i.e. 60 minutes/one hour = 1; 30 minutes/½ hour = 0.50; etc) the appliance operates at full load.


  • Figure out the cost per KWH
    You can calculate the current cost per KWH by checking your electric bill.

Divide the TOTAL CURRENT CHARGE (bill detail section) by the KWH USAGE (bill period section).



  • Calculate the Operating Cost
    Now you can figure out the cost for using your appliance per full-load use.

Multiply the KWH for the appliance by the cost per KWH.


Things to Consider 

  • Horsepower
    Motors are often rated in horsepower.  One horsepower is roughly equal to one kilowatt.
  • Amps & Volts
    If the wattage is not listed on the appliance, but the amps and volts are listed, you can calculate the wattage.

Multiply the amps by the volts