Space heaters are a popular way to warm specific rooms without heating your entire home. But before you plug one in, you need to know how much it will cost. The answer depends on three simple factors: your heater’s wattage, how long you run it, and your electricity rate.
The Space Heater Cost Formula
Calculating your space heater’s operating cost is straightforward:
Cost = (Watts x Hours x Electricity Rate) / 1000
Here’s what each part means:
- Watts: Your heater’s power consumption (typically 750W, 1000W, or 1500W)
- Hours: How long you run the heater
- Electricity Rate: Your cost per kilowatt-hour (kWh), found on your utility bill
- Divide by 1000: Converts watts to kilowatts
For example, a 1500W heater running for 8 hours at $0.15/kWh costs:
(1500 x 8 x 0.15) / 1000 = $1.80
Hourly Operating Costs
Most space heaters fall into three wattage categories. Here’s what they cost per hour at common electricity rates:
| Wattage | $0.10/kWh | $0.15/kWh | $0.20/kWh | $0.25/kWh | $0.30/kWh |
|---|---|---|---|---|---|
| 750W | $0.08 | $0.11 | $0.15 | $0.19 | $0.23 |
| 1000W | $0.10 | $0.15 | $0.20 | $0.25 | $0.30 |
| 1500W | $0.15 | $0.23 | $0.30 | $0.38 | $0.45 |
The national average electricity rate is approximately $0.15/kWh, though rates vary significantly by state. California and Hawaii exceed $0.30/kWh, while states like Louisiana and Idaho average closer to $0.10/kWh.
Daily Operating Costs
Running a space heater all day adds up quickly. Here are daily costs based on 8 hours of use (a typical workday or evening):
| Wattage | $0.10/kWh | $0.15/kWh | $0.20/kWh | $0.25/kWh | $0.30/kWh |
|---|---|---|---|---|---|
| 750W | $0.60 | $0.90 | $1.20 | $1.50 | $1.80 |
| 1000W | $0.80 | $1.20 | $1.60 | $2.00 | $2.40 |
| 1500W | $1.20 | $1.80 | $2.40 | $3.00 | $3.60 |
If you run your heater for 12 hours daily, multiply these figures by 1.5. For 24-hour operation, double them.
Calculate Your Space Heater Costs
Enter your wattage and electricity rate for exact costs.
Calculate Costs NowWeekly Operating Costs
For a full week of use (8 hours per day, 7 days), expect these costs:
| Wattage | $0.10/kWh | $0.15/kWh | $0.20/kWh | $0.25/kWh | $0.30/kWh |
|---|---|---|---|---|---|
| 750W | $4.20 | $6.30 | $8.40 | $10.50 | $12.60 |
| 1000W | $5.60 | $8.40 | $11.20 | $14.00 | $16.80 |
| 1500W | $8.40 | $12.60 | $16.80 | $21.00 | $25.20 |
Monthly Operating Costs
Monthly costs assume 8 hours of daily use for 30 days:
| Wattage | $0.10/kWh | $0.15/kWh | $0.20/kWh | $0.25/kWh | $0.30/kWh |
|---|---|---|---|---|---|
| 750W | $18.00 | $27.00 | $36.00 | $45.00 | $54.00 |
| 1000W | $24.00 | $36.00 | $48.00 | $60.00 | $72.00 |
| 1500W | $36.00 | $54.00 | $72.00 | $90.00 | $108.00 |
At the national average rate of $0.15/kWh, a 1500W space heater costs roughly $54 per month when used 8 hours daily.
Factors That Affect Your Actual Costs
Thermostat Settings
Most modern space heaters include thermostats that cycle the heating element on and off to maintain temperature. A heater with a thermostat may only run at full power 50-70% of the time, reducing your actual costs below the maximum figures shown above.
Room Size and Insulation
A well-insulated room heats faster and retains warmth longer, meaning your heater cycles off more frequently. Poor insulation or drafty windows force continuous operation, maximizing energy use.
Heater Type
While all electric heaters convert electricity to heat at nearly 100% efficiency, different types distribute heat differently:
- Ceramic heaters: Heat up quickly, good for small spaces
- Oil-filled radiators: Heat slowly but maintain warmth after shutoff
- Infrared heaters: Heat objects directly rather than air
The type affects comfort more than energy consumption, as all electric resistance heaters use the same amount of electricity for equivalent heat output.
Tips to Reduce Space Heater Costs
- Use a programmable thermostat: Set the heater to turn off when you’re asleep or away
- Heat only occupied rooms: Close doors and focus heating where you need it
- Lower your central thermostat: If supplementing central heating, reduce the whole-house temperature
- Maintain your heater: Clean filters and vents ensure efficient operation
- Choose the right size: An oversized heater wastes energy; match wattage to room size
Space Heater vs. Central Heating
Space heaters make financial sense when heating one or two rooms while keeping the rest of your home cooler. If you’re running multiple space heaters throughout your home, central heating is almost always more economical.
The break-even point depends on your central heating system’s efficiency, your home’s size, and how many rooms you need to heat. As a general rule, space heaters work best for:
- Home offices during work hours
- Bedrooms at night
- Supplemental heating in cold rooms
- Homes where occupants spend time in only one or two rooms
The Bottom Line
A typical 1500W space heater costs between $0.15 and $0.45 per hour to run, depending on your electricity rate. Monthly costs range from $36 to $108 for 8 hours of daily use. Know your heater’s wattage and your local electricity rate, apply the simple formula, and you’ll have an accurate estimate of your operating costs.