Understanding the Power Requirements
Electric space heaters are unusual among the appliances people want to power on generators because they have no startup surge — what you see is what you get. A 1,500-watt space heater draws exactly 1,500 watts continuously the entire time it's running. This makes generator sizing straightforward: add 1,500 watts to your other loads and size from there.
Almost all plug-in electric space heaters max out at 1,500 watts on the high setting (the maximum for a standard 120V/15A circuit). Most have low (750W) and high (1,500W) settings. Oil-filled radiators use the same wattage as traditional space heaters. Ceramic disc heaters, infrared heaters, and fan heaters are all 1,500W maximum on 120V circuits.
Choosing the Right Generator Size
A 2,000-watt generator technically runs one space heater — but leaves only 500 watts for other loads. If you want a space heater plus refrigerator plus lights, plan for 3,500 watts minimum. One important note: gas furnaces only need the electric blower motor (600–1,200W) to run. If you have a gas furnace, powering the blower is far more efficient than running an electric heater.
Wattage Summary
| Specification | Value |
|---|---|
| Running Watts | 1.5 kW |
| Surge Watts | 1.5 kW |
| Minimum Generator | 2 kW |
| Recommended Generator | 3.5 kW |
Buying Tips
A gas furnace only needs 600–1,200 watts for the blower motor — far more efficient than a 1,500W electric heater for heating a whole home.
Running one space heater in the room you're occupying is much more efficient than trying to heat your whole home.
Space heaters with thermostats cycle on and off, which reduces average power consumption to 750–1,000W vs. continuous 1,500W.
Infrared heaters are slightly more efficient for spot heating because they heat objects rather than air — heat isn't wasted on warm air escaping.
What Else Can Run With It?
Common appliances paired with this load. Combined running load: 1.9 kW. Recommended generator for this combo: 3.5 kW.
| Appliance | Running Watts |
|---|---|
| Space Heater ← this page | 1500W |
| Refrigerator | 150W |
| LED Lights | 100W |
| Phone Chargers | 50W |
| TV | 120W |
| Combined Running Total | 1.9 kW |
* Recommended generator for this combination: 3.5 kW (includes 20% safety margin and surge headroom)