How to Calculate Any Appliance's Electricity Cost

The universal formula

Electric bills charge for energy in kilowatt-hours, so first divide watts by 1,000 to get kilowatts. Multiply kilowatts by active hours and then by the electricity rate in dollars per kWh.

Read the rate from your bill

A state average is useful when comparing locations, but your own bill is better for a household estimate. Divide usage-based electricity charges by billed kWh when the bill does not show a single combined rate, while keeping unavoidable fixed monthly fees separate.

• Convert cents per kWh to dollars by dividing by 100.
• Use the matching on-peak or off-peak price for time-of-use loads.
• Do not add the same fixed customer charge to every appliance.

Handle appliances that cycle

Refrigerators, air conditioners, heaters, pumps, and dehumidifiers do not always draw full power for every clock hour they are switched on. Use equivalent full-power hours, a duty-cycle estimate, annual kWh from an EnergyGuide label, or a measured kWh total.

Check the result against reality

Compare the calculated monthly kWh with the total household kWh on the bill. If one appliance estimate exceeds the entire bill, the wattage, unit conversion, or runtime assumption is wrong.

• Use input watts, not output capacity such as BTU or cooling watts.
• Convert minutes to hours and cents to dollars consistently.
• Measure variable or cycling loads over a representative period.