Space Heater Cost Calculator

How the space heater estimate works

The calculator converts watts to kilowatts, multiplies by effective runtime, and then applies the electricity price. With the starting inputs, this space heater uses about 180.0 kWh per month.

Thermostats cycle the element on and off. Treat the estimate as a full-power ceiling unless you have measured the outlet.

How runtime changes the estimate

These scenarios assume the device draws the full starting wattage for the entire runtime. Cycling and variable-speed equipment should use effective runtime or measured kWh.

How much does a space heater cost to run?

A 1,500-watt space heater uses 1.5 kWh for every full-power hour. Multiply that energy by your electricity price to get the hourly cost, then multiply by actual heater runtime—not simply the hours the heater is switched on.

The thermostat may cycle the heating element after the room reaches its setting. A plug-in energy meter can capture that cycling and produce a better estimate than nameplate wattage alone.

Space heater cost by power setting

Each example assumes four full-power hours per day for 30 days. Thermostat cycling can reduce actual energy use. Costs use the latest 2026-05 U.S. residential average of 18.44¢/kWh.

When a space heater can—and cannot—lower the bill

Heating one occupied room can cost less than raising the temperature throughout a large home, but only if the central system is actually turned down and the portable heater is used safely in a limited area.

Several 1,500-watt heaters running for long periods can quickly become a major winter load. Compare the same delivered-heating need before treating a portable heater as an alternative to a heat pump or central system.

Estimated monthly cost in high-price states

Practical ways to reduce cost

• Heat the occupied room instead of the whole home.
• Use the thermostat rather than running continuously.
• Seal drafts before increasing the setting.

Compare related equipment

Frequently asked questions