Space Heater Running Cost Calculator
Space heaters are sold as a cheap way to stay warm. Sometimes they are. Often they are the most expensive heat in the house — this shows which case you're in.
Rates and assumptions reviewed · see every source
The one thing to understand
Every electric resistance heater is exactly 100% efficient. Not "very efficient" — exactly 100%. All the electricity becomes heat, because that is what electrical resistance does.
That sounds excellent until you compare fuels. Electricity at 18.3¢/kWh delivers heat at 18.3¢ per kWh of warmth. Natural gas at $1.55/therm through a 95% furnace delivers the same kWh of warmth for about 5.6¢. Electric heat costs roughly three times more per unit of heat.
So a space heater saves money only if it lets you heat less. One room warm and the thermostat down 5°F can genuinely cut a bill. A space heater running alongside unchanged central heating is pure added cost — and that is how most people actually use them.
All resistance heaters cost the same to run
Ceramic, oil-filled, infrared, quartz, mica panel, "eco" — at the same wattage they cost identically. A $200 designer heater and a $25 supermarket one both drawing 1500W produce the same heat for the same money.
What genuinely differs: how quickly heat spreads, noise, safety cut-outs, and whether there is a thermostat. That last one matters for cost — a thermostat cycles the heater off once the room is warm, cutting duty cycle to perhaps 50% and halving the bill.
What it costs
| Heater | Per hour | 8h/day | 120-day season |
|---|---|---|---|
| 400W personal heater | 7.0¢ | $0.56 | $67 |
| 750W (low setting) | 13.8¢ | $1.10 | $132 |
| 1500W (typical) | 27.5¢ | $2.20 | $264 |
| 1500W with thermostat (50% duty) | 13.8¢ | $1.10 | $132 |
| Two 1500W heaters, 12h/day | 52.4¢ | $6.29 | $754 |
At $0.1834/kWh.
When a space heater is the right answer
- One room, thermostat down. Heating a home office to comfortable while the rest of the house sits at 62°F genuinely saves.
- Occasional use. A cold snap, a draughty room, an hour in the morning — cheap to buy, no installation.
- No central heating. Against nothing, any heat wins.
- Electric-heated home already. If your whole house is resistance heat, a space heater costs no more per unit and lets you heat selectively.
When it is the wrong answer
- Running alongside central heating at the same setting. Pure added cost, no saving whatsoever.
- Heating a large or draughty space. 1500W cannot keep up, so it runs continuously at full cost and still feels cold.
- All day, every day, all winter. At that duty cycle a mini-split heat pump repays its installation in a few seasons.
A safety note worth the space
Space heaters are a leading cause of home heating fires. Keep three feet of clearance from anything flammable, never run one on an extension lead or power strip — a 1500W heater draws 12.5A and will overheat most cords — and only buy units with automatic tip-over and overheat shut-off.
Related
Common questions
Are space heaters cheaper than central heating?
Only when you heat one room instead of the whole house. A 1500W heater costs about 27.5¢ an hour — roughly the same as running a gas furnace, which heats your entire home. If you run a space heater while the central heating is also on, you are simply adding cost. The saving comes exclusively from turning the thermostat down and heating one room, never from the heater being efficient.
Are some space heaters more efficient than others?
No, and this is the most common misconception. Every electric resistance heater — ceramic, oil-filled, infrared, quartz, panel, 'eco' — converts essentially 100% of its electricity into heat. A $200 heater and a $25 heater drawing 1500W produce identical warmth for identical cost. Differences are in how heat is distributed, how quiet it is, and safety features. Any advert claiming a resistance heater is 'more efficient' or 'saves 50% on heating' is misleading you.
What about the ones advertised as costing pennies a day?
Those adverts rely on you not checking the wattage. A heater genuinely costing pennies a day draws 300–400W and heats roughly the volume of a desk footwell. The 1500W models that actually warm a room cost around $2.20 a day at eight hours' use. Physics does not permit a 1500W device to be cheap to run.
Is a heat pump a better option?
Substantially. A mini-split heat pump delivers 2.5–4 units of heat per unit of electricity, versus exactly 1 for any resistance heater. Running costs fall by roughly two-thirds. The catch is $2,000–5,000 installed against $40 for a plug-in heater, so it only makes sense as a permanent solution for a room you heat every day.