How Much Does It Cost to Run a Space Heater?

A space heater is one of the simplest appliances to figure the running cost of, because nearly all the electricity it draws turns straight into heat. At the US average electricity rate, a standard 1,500-watt space heater costs roughly 25¢ an hour to run — about $2 for an 8-hour night. Whether that's cheap or expensive comes down to one thing: how many you run and for how long. This guide gives you the simple math, a cost table for different rates, and the honest answer on when a space heater beats central heat.

The simple formula

Every space heater's running cost comes from three numbers: its wattage, the hours you run it, and your electricity rate. The formula is:

Cost = (watts ÷ 1,000) × hours × rate per kWh

Dividing watts by 1,000 converts to kilowatts; multiplying by hours gives kilowatt-hours (kWh); multiplying by your rate turns kWh into dollars. That's it — a space heater has no efficiency curve to worry about, because a resistance heater converts essentially 100% of the electricity it draws into heat. The wattage on the label is the whole story.

Worked example. A 1,500-watt heater, run 8 hours, at the US average rate of about 17¢/kWh:

• 1,500 ÷ 1,000 = 1.5 kW
• 1.5 kW × 8 hours = 12 kWh
• 12 kWh × $0.17 = ~$2.04

So a full night on high costs about two dollars. Run it 8 hours a day for a month and that's roughly $60. Cut the wattage in half (many heaters have a 750-watt low setting) and you cut the cost in half.

Cost per hour at different rates

Because electricity prices vary widely by state, the same heater costs very different amounts depending on where you live. The table below shows the cost to run a 1,500-watt heater at common rates. All figures assume the heater runs at full power the whole time.

Find your state's typical rate on our electricity rates page, then read across. If your heater is a lower-wattage model, scale the numbers down proportionally — a 1,000-watt heater costs two-thirds as much, a 750-watt heater half.

Cost by heater wattage

Not every space heater is 1,500 watts. Smaller personal heaters and many "low" settings draw less, which changes the cost directly. At the US average 17¢/kWh, here's the cost per hour by wattage:

The pattern is simple: cost scales directly with wattage. Using the low setting when it keeps you comfortable is the easiest saving there is. For per-appliance running costs across your whole home, our cost to run a space heater reference has ready-made numbers, and you can price any wattage-and-hours combination yourself with the electricity cost calculator.

When a space heater is cheaper than central heat

Here's the nuance most articles miss. A space heater gets a bad reputation as an energy hog, but used correctly it can save money — the key word is correctly.

A space heater wins when you heat one room and turn the central system down. If you spend the evening in one room, running a 1,500-watt heater there (about 26¢/hour) while dropping the whole-house thermostat can cost less than heating 2,000 square feet to the same comfort. You're heating 150 square feet instead of the entire house. This is "zone heating," and it's where the savings live.

A space heater loses when it's doing whole-home duty. Because it's electric-resistance heat — the least efficient way to heat — running several heaters all day to warm a whole house costs far more than a central furnace, and dramatically more than a heat pump, which moves heat instead of generating it and delivers 2–4 units of heat per unit of electricity. Three 1,500-watt heaters running all day is 4,500 watts of resistance load — a fast track to the winter bill spikes people dread.

The rule of thumb:

• One heater, one occupied room, central heat turned down → often the cheaper choice.
• Multiple heaters or whole-home heating → expensive; a heat pump or central system wins big.

How to run one for less

A few habits keep the cost down without leaving you cold:

• Use the thermostat. Let the heater cycle off once the room is warm instead of running flat out — most of the time on high is wasted heat.
• Run the low setting when it's enough. Half the watts is half the cost.
• Heat the room you're in, and close the door. Keeping heat in the space you occupy is the entire savings mechanism of zone heating.
• Turn the central thermostat down while zone heating — if the furnace still runs to keep the whole house warm, you've added cost instead of shifting it.
• Never leave one running in an empty room. A heater warming nobody is pure waste, and a running heater is also a safety consideration — always follow the manufacturer's clearance and supervision guidance.

The bottom line

A space heater costs about 25¢ an hour on high at the average US rate — roughly $2 a night, or scale it to your own rate and wattage with the simple watts ÷ 1,000 × hours × rate formula. One heater warming the room you're actually in, with the central thermostat turned down, is often the cheapest way to stay comfortable. The cost only becomes a problem when heaters multiply or try to heat a whole house — resistance heat is expensive at scale, and that's a heat pump's job. Price your exact setup with the calculator below.