Is it cheaper to run a space heater than central gas heat?

Usually no, unless you turn down your central thermostat by at least 7 to 10 degrees. Natural gas provides significantly more BTUs per dollar than electric resistance heating elements.

Is a space heater cheaper than an oil or propane furnace?

Yes. Heating oil and delivered propane are substantially more expensive per BTU than natural gas, making single-room space heating an effective money saver.

Space Heater vs. Central Furnace Cost Decider

1. Electric Space Heater

Heater Wattage (W)

Hours Used (e.g. Nightly)

Electric Rate ($/kWh)

Hourly: $0.00

Total Run Cost: $0.00

2. Central Heating System

Furnace Fuel Type

Fuel Price ($ / Therm)

Furnace Input (BTU/hr)

Furnace Efficiency (AFUE)

Hourly: $0.00

Total Run Cost: $0.00

3. Thermostat Strategy

Whole-House Temperature Setback

Space heaters do not heat an entire home. Savings occur only when you lower your central thermostat while warming just the room you are in.

How the Space Heater vs. Furnace Calculation Works

Electric space heaters operate at 100% electrical efficiency: every watt drawn is converted into heat. However, electricity is an expensive heat source compared to piped natural gas.

To generate 100,000 BTUs of heat:

Natural Gas (80% Furnace): Consumes ~1.25 therms (approx. $1.81 at $1.45/therm).
Electric Resistance: Requires 29.3 kWh (approx. $4.92 at $0.168/kWh).

Because electric resistance heating costs roughly 2.7× more per BTU than natural gas, turning on a space heater without lowering your central thermostat will always increase your monthly utility bill. Zoned heating saves money only when you dial your whole-house thermostat down far enough to offset the space heater's electrical draw.