How to Figure Out an Electric Furnace's Kilowatt Usage

Look for the furnace's wattage listing. Typically, this is listed, along with other information such as the model, serial number and manufacturer's name, on a sticker or plate stuck to either the outside or inside of the furnace cabinet.

Calculate the furnace wattage if the information isn't listed on the name plate. Sometimes an appliance will list volts (either 120 or 220) and amps instead. These will be clearly labeled. Multiply the volts by the amps to obtain the total watts your electric furnace consumes in one hour.

Divide the furnace's watts by 1,000 to determine the kilowatts it uses. This represents the amount of energy used in one hour of operation, as measured in a thousandth of a watt reading.

Multiply the kilowatts used per hour by the number of hours that the furnace runs to determine the number of kilowatt-hours per day your furnace consumes. Find the average monthly use by multiplying the kilowatt-hours by 30 days. The result, when multiplied by the cost per kilowatt-hour (look on your electric bill to determine) shows how much the furnace actually costs to run for that month.