In almost every part of North America, if not every part, it costs more to heat your house with electricity than it does to use gas. Part of the reason for that is that most electric heaters generate heat by electrical resistance, which involves passing electric current through a heating element to make it glow red hot and give off heat. Resistive heaters use a lot of electricity.
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Electric heat pump technology provides a more efficient way to heat with electricity, but it may not provide enough heat for the coldest days. That means if you rely solely on electricity for heat, you'll probably have at least one resistive heater. You can calculate your monthly electricity expenditure by adding up the costs for all of your individual heaters, resistive and otherwise.
Calculating the Cost for One Heater
Power companies charge for electricity by the kilowatt-hour (kWh), and United States mainland costs vary from 9 cents in Nebraska (the lowest) to 25 cents in Massachusetts (the highest), according to 2022 data from the U.S. Energy Information Administration. The average cost is about 14 cents.
To calculate how much a heating device costs per month, you need to know how many watts it draws and how many hours it stays on. The wattage is usually displayed on a label next to the power plug, although on some devices, only the current draw is displayed. If that's the case, you calculate the wattage by multiplying the current draw by the voltage, which is either 120 or 240 volts depending on the type of heater.
A Sample Calculation
Suppose you have a plug-in space heater that operates in only one power mode. Such a device typically draws 1,500 watts (1.5 kW). If the label only displays current draw, the current rating is typically 12.5 amps (12.5 amps x 120 volts = 1,500 watts). To figure out how much it costs to operate the heater per month, determine how many hours you use the heater in a month, multiply by the wattage, and then multiply by your local electric rate.
If the heater in question runs for four hours a day on average, that's equivalent to 120 hours of use for each 30-day month. Multiply by the wattage to determine that it consumes 180 kWh of electricity per month. If you are charged the national average electric rate of about 14 cents per kWh, you're spending $25.20 per month to run the heater.
The Cost of All the Sources of Heat at Home
Essentially, you calculate your total energy costs by performing this calculation for each heater in your house and adding the results, keeping in mind some considerations:
- Some electric space heaters draw only 1,200 watts, and some have low-power modes that draw 350 or 600 watts. If you change power modes, you have to perform separate calculations for each power mode.
- Built-in and baseboard heaters frequently operate at 240 volts, not 120. Multiply the current draw displayed on the label by the higher voltage to calculate the power draw of the heater.
- If you have panel heaters, each one usually draws 400 watts.
The power draw of a whole-house heat pump varies, but it's typically about 3.5 kW per hour. That sounds like a lot, but remember that it's heating the entire house, not just a single room. The cost works out to 49 cents per hour at the average national rate, and if the heater runs 20 hours a day, it's about $294 per month. That's not bad considering that a 1.5 kW single-room space heater would cost $126 if you used it for the same amount of time.