How many watts does an electric furnace use?

Heating and cooling bills are some of the biggest expenses of owning or renting property. For that reason, it's important to know just how much electricity an electric furnace uses when you're looking at your whole home's energy usage.

Generally, electric furnaces use 10,000 to 50,000 watts (W) of electricity, depending on the model. On average, it's safe to assume that electric furnaces in standard residential homes use about 20,000 W. Most electric furnaces use between 60 and 80 amps and connect to a 220 volt breaker.

Importantly, furnaces generally have a much lower "running" wattage than their stated wattage – this is because they cycle on and off throughout the day. As a general rule of thumb, furnaces cycle on and off 2-3 times each hour for about 15-20 minutes at a time, which is about 35 minutes in every hour. So, a 20,000 W electric furnace actually will use about 13,000 W each hour.

There's one more important caveat to remember with electric furnaces: they just don't make much financial sense in many parts of the U.S. In fact, the Southeast and Southwest regions are the only areas of the country where electric furnaces are somewhat common, and those areas might only need a few hours of heating per day. As such, we'll use an average of two hours of electric furnace heating needed per day in our calculations.

How much you run your electric furnace has the biggest impact on how much electricity it uses over time:

How much electricity do electric furnaces use?

*Assuming two hours of operation per day
**Assuming two hours of operation per day, and four months per year

Different wattage electric furnaces use different amounts of electricity over the course of a year. Assuming again that the average electric furnace is run for two hours per day for four months of the year, here's how much electricity you'll use over the course of a full calendar year:

How many watts do different electric furnaces use in a year?

We'll mostly be referring to the electricity used by electric furnaces in terms of kWh in this article. The reason is simple: your electric bill is measured in kWh, and you get charged based on the kWh of electricity you use per month!

When you get your monthly electric bill, you only get to see the total amount you're charged, not how much each appliance contributes to your final bill. Based on an average wattage of 20,000 W for electric furnaces (amounting to 3,163 kWh/year if you use your electric furnace like an average household would) and using state average electricity rates, here's how the cost to run an electric furnace pans out over the course of a month (on average) and a year:

Monthly and yearly costs to run an electric furnace by state

Note: average electricity rates are based on October 2021 data from the U.S. Energy Information Administration (EIA).

Importantly, most households that use electric furnaces only need to use them for about four months out of the year on average. The monthly cost numbers in the table above simply reflect the yearly estimated cost divided by 12 months – but in reality, you can divide your yearly cost by four for a more accurate picture of what one month's electric bill will look like when you're running an electric furnace. For example, homeowners in California might expect to spend $174 per month for only four months on heating ($696 / 4 months).

Looking to offset your electric bills (and the energy these appliances use) with solar? When you sign up (for free!) on the EnergySage Marketplace, you can compare solar quotes from high-quality, local solar installers. Make sure to keep in mind your current and future electricity usage, and talk about how that could change with your installer for the most accurate quotes.

What's the best time to run an electric furnace?

If you're on a time-of-use (TOU) rate plan, you are charged different amounts for electricity throughout the day. In general, it's cheaper to use an electric furnace during "off-peak" hours, which are usually overnight. For an electric furnace, you may have less of an option, as you'll just need to run it when it's colder.

What size battery do you need to back up an electric furnace?

Most lithium-ion batteries like the Tesla Powerwall or Generac PWRcell have a power rating of 4 to 5 kW or higher and 10+ kWh of usable capacity. Electric furnaces use about 20,000 W (1.5 kW) of power at any one time, meaning you'll need several batteries worth of power to keep an electric furnace running for any extended period of time.

How many solar panels does it take to power an electric furnace?

Average electric furnaces use 20,000 W of electricity to stay powered. On average, solar panels are rated at around 350 W, meaning you'll need a whopping 50-60 solar panels to provide enough power to an electric furnace.

What are ENERGY STAR appliances?

ENERGY STAR is a U.S. government-backed system that certifies how energy efficient appliances are. If an appliance is better than the average appliance in its category by a certain amount, it is labeled as "ENERGY STAR certified." ENERGY STAR appliances cost less money to run, given that they are more efficient with the electricity they use.

Solar savings vary widely, and your unique savings depends on factors like electricity usage, your location, electric rates and plans, and more. In general, most homeowners can expect to save somewhere between $10,000 and $30,000 over the lifetime of a solar panel system. On average, it takes between 7 and 8 years for most homeowners who shop for solar on EnergySage to get their solar panels to pay for themselves.

Going solar is one of the most effective ways to reduce or eliminate your electric bill, and you should make sure you are getting several quotes from reputable installers before you decide to move forward. Visit the EnergySage Marketplace to get solar quotes from installers in your area and begin comparing options.