How much does it cost to run a portable space heater?
A portable space heater is a compact electric heating device that warms a single room by converting electricity directly into heat through a heating element. Because they operate at high wattage—typically between 750 and 1500 watts—and deliver that energy in concentrated bursts to small spaces, they consume far more electricity per unit of warmth than central heating systems.
Portable Space Heater running cost calculator
- Per day
- $1.53
- Per month
- $19.13
- Per year
- $229.50
- CO₂ / year
- 540 kg
Based on 1350 kWh per year. Adjust the price per kWh to match your latest electricity bill for an exact figure.
At 1500 watts used 6 hours a day, a portable space heater costs about $1.53 per day, $19.13 per month and $229.50 per year on an average rate of 17¢ per kWh — roughly 1350 kWh and 540 kg of CO₂ over a year. Enter your own electricity rate and usage in the calculator above for a figure matched to your bill.
Portable space heaters are almost purely resistive devices, meaning nearly all the electricity they draw gets converted to heat with minimal losses. This makes them very efficient in a technical sense, but the catch is that resistance heating is one of the most expensive ways to generate warmth using electricity. When you plug in a 1500-watt heater, it draws that full load whenever the thermostat calls for heat, creating demand charges and extended runtime that quickly compound your bill, especially if you're running the heater for several hours daily across winter months.
The real driver of operating costs is how long and how often you run the heater. A unit running six hours per day during a 150-day heating season will accumulate significant total usage. Most people underestimate how frequently they leave a heater running—it's easy to turn one on in the morning and forget to power it down, or to keep it going all day because the main thermostat is set conservatively. Even a small reduction in daily runtime or a modest bump to your central thermostat in exchange for zone heating can substantially lower overall costs.
When selecting a portable space heater, prioritize models with built-in thermostats and automatic shutoff features. Many budget heaters lack thermostatic control, meaning they run at full power continuously until manually switched off. Higher-end units include dial or digital thermostats that cycle the heating element on and off to maintain a target room temperature, eliminating wasted cycles. Tip-over protection and overheat shutoffs are essential safety features that should be standard, as is a power indicator light so you remember the heater is running.
Placement and room conditions dramatically affect efficiency and runtime. A heater in a drafty room, near windows, or in spaces with poor insulation will run longer to maintain comfort because warm air escapes faster. Using a space heater only in the room you're actively using, rather than trying to heat an entire house, is the most sensible approach. Closing off unused rooms, sealing obvious air leaks, and using the heater as a supplement to central heating at lower thermostat settings creates a much more cost-effective heating strategy than relying on portable units as primary heat sources.
Wattage ratings can be misleading because they don't directly tell you how warm a room will actually get. A 1500-watt heater won't necessarily heat faster or better than a 1000-watt model if the latter has superior heat distribution or a more responsive thermostat. Look for heater designs with fans that distribute warmth more evenly throughout the room, and consider the room size for which the unit is rated—heating a large, open living room with a small bedroom heater will result in constant running and wasted energy. Energy-efficient models often cost more upfront but pay for themselves through reduced operating costs if you're heating regularly.
Frequently asked questions
- Why does my portable space heater cost so much to run compared to my central furnace?
- Electric resistance heating is inherently expensive because it converts electricity directly into heat. Central furnaces burn gas, which is typically much cheaper per unit of energy than electricity in most regions. Portable heaters also often run at full power without modulation, whereas furnaces can vary their output. The real cost difference becomes obvious when you run a heater several hours daily—the electrical demand adds up quickly.
- Does buying a 'low wattage' space heater save money?
- A 750-watt heater will cost less to run than a 1500-watt model, but it will also heat slower and need to run longer to reach the same temperature. The total cost savings depend on how much longer it must run. If a low-wattage heater means you're running it an extra 3–4 hours per day to achieve comfort, you may not save anything. Choose wattage based on room size and heating speed you need, not wattage alone.
- What's the difference between a heater with a thermostat and one without?
- A thermostat-equipped heater cycles on and off to maintain your target temperature, reducing overall runtime and electricity use. A manual-only heater runs at full power the entire time it's switched on, even if the room has already reached your desired warmth. For any heater you plan to use for more than a few minutes at a time, thermostat control is essential for cost management.
- Is it cheaper to heat one room with a space heater or lower my whole-house thermostat?
- If you're only using one or two rooms, zoning with a space heater in those rooms while lowering the central thermostat is usually cheaper than heating the entire house. However, the savings depend on how many rooms you're abandoning and the thermostat difference. Using a heater in a single occupied room while setting central heat to 60–62°F in unused spaces typically wins out; heating an entire house but turning central heat off entirely to use only space heaters is rarely cost-effective.
- What features should I look for to minimize operating costs?
- Prioritize a reliable built-in thermostat, automatic shutoff or tip-over protection to prevent accidental extended runtime, and a fan for even heat distribution. Some models include a timer feature that automatically powers down after a set time, which helps prevent forget-and-leave scenarios. Avoid heaters without thermostats, and be skeptical of marketing claims about 'energy-saving' or 'eco' models that are simply smaller or lower-wattage versions of standard designs.
- Can I leave a portable space heater running overnight or while I'm away?
- Most modern space heaters include overheat protection and shutoff features, making them safer for unattended use than older models, but it's still not recommended for extended periods. Leaving a heater running overnight or while away uses significant electricity with no one benefiting from the warmth. Set your heater to run only when you're present and awake to control usage, and rely on central heating or a lower thermostat setting to maintain baseline comfort in your absence.