How Much Does It Cost to Run a Space Heater?

How to Calculate Space Heater

To estimate the running cost, convert the heater’s wattage to kilowatts and multiply it by the operating time and your electricity rate:

Cost = (watts ÷ 1,000) × hours used × electricity rate ($/kWh)

If the heater’s thermostat switches the heating element on and off, use effective heating hours rather than the total time the unit remains switched on.

Example Calculation for a 1,500-Watt Space Heater

Consider a 1,500-watt space heater used for six effective heating hours per day with an illustrative electricity rate of $0.16 per kWh.

1,500 watts ÷ 1,000 = 1.5 kilowatts

1.5 kW × 6 hours = 9 kWh per day

9 kWh × $0.16 = $1.44 per day

$1.44 × 30 days = $43.20 per month

This example assumes that the heating element draws its full rated power for all six hours. A thermostat that cycles the heater on and off may reduce its effective operating time and actual cost

Factors That Affect the Final Cost

The estimated cost depends mainly on four inputs: the heater’s wattage, its effective operating time, your electricity rate, and the number of days it is used.

Room size, insulation, outdoor temperature, drafts, and thermostat settings affect how frequently the heating element operates. A poorly insulated or larger room may require the heater to run for longer to maintain the same temperature.

Electric resistance heaters with the same wattage and effective operating time will generally have similar electricity costs. Features such as thermostats, timers, fans, and multiple heat settings may improve temperature control or reduce operating time, but the advertised heater type alone does not determine the final cost.

Finding Your Electricity Rate

Check your latest electricity bill for the energy charge expressed in dollars per kilowatt-hour ($/kWh). If the rate appears in cents, divide it by 100. For example, 16 cents per kWh should be entered as $0.16 per kWh.

Use the variable electricity charge that applies to your consumption. Fixed customer charges and unrelated fees are not included in this simple appliance-cost estimate.

If your price changes according to the time of day, calculate each rate period separately and add the results together.

Tips for Using a Space Heater Efficiently

Use the heater only in occupied rooms and close doors and windows to keep the heat within the space. Sealing drafts and improving insulation can reduce the amount of time the heating element needs to operate.

Choose the lowest comfortable heat setting and use the thermostat or timer when available. Turning the heater off when it is no longer needed directly reduces energy consumption.

For safe operation, place the heater on a stable, level surface and keep it at least three feet away from curtains, bedding, furniture, clothing, paper, and other combustible materials.

Plug an electric space heater directly into a wall outlet. Do not use an extension cord or power strip, and never leave a portable heater operating while sleeping or unattended.

For additional safety guidance, see the U.S. Consumer Product Safety Commission:

https://www.cpsc.gov/Newsroom/News-Releases/2025/Theres-a-Chill-in-the-Air-Stay-Warm-Safely-Be-Cautious-When-Using-Generators-Furnaces-and-Space-Heaters

Final Takeaway

A 1,500-watt space heater uses 1.5 kWh of electricity for every hour that its heating element operates at full power. Multiply that consumption by the effective operating time and your electricity rate to estimate the cost.

In the example above, six effective heating hours per day at an illustrative rate of $0.16 per kWh would cost approximately $43.20 over 30 days. Your actual result may differ because of thermostat cycling, room conditions, usage habits, and local electricity prices.

Use the WattBasis Electricity Cost Calculator to enter your own wattage, operating time, and electricity rate:

https://wattbasis.com/electricity-cost-calculator

These calculations are educational estimates. Always follow the heater manufacturer’s operating and safety instructions.