Space Heater vs Central Heat: Which Is Actually Cheaper?
Space heaters buy the most expensive heat there is — about $0.16 per kWh of heat at the US average rate, against $0.064 for a typical heat pump. They win anyway when you heat fewer than about 2.0 of 5 rooms and turn the central thermostat down. Heat one room for 8 hours a day and you pay $57.60 a month, versus $115.20 to hold the whole house at temperature — a $58 monthly saving. Plug in a second and third heater and central heat wins.
Run it on your own rate, room count, and heating system below — or see the full cost to run a space heater breakdown.
Space Heater vs. Central Heat Calculator
Units of heat moved per unit of electricity. Drops toward 1.5-2 in freezing weather.
Space heaters are cheaper by $57.60/month
Heating 1 of 5 rooms with 1500W heaters for 8 hours a day, vs. holding the whole home at temperature with the central system.
Break-even is about 2.0 of your 5 rooms. Heat fewer rooms than that and space heaters win; heat more and the central system does.
Space heaters (1 room)
Electric resistance heat, COP 1.0
Central heat pump (5 rooms)
COP 2.5
Both sides are priced per kWh of heat actually delivered into the rooms. The model assumes every room needs the same heat input to hold temperature, that space heaters run only in the rooms you count, and that the central system holds the whole home at temperature. Monthly figures use a 30-day month. A gas therm is treated as 100,000 BTU (29.3 kWh) of heat before furnace losses.
The Whole Comparison Is One Number
Cost per kWh of heat = price of the fuel ÷ how much heat it delivers
A space heater is electric resistance heat: one kWh of electricity in, one kWh of heat out. Its heat costs exactly your electricity rate — $0.16/kWh on average. A heat pump doesn't make heat, it moves it, delivering 2.5 kWh of heat per kWh of electricity (its COP), so the same warmth costs $0.064/kWh. A gas furnace burns a therm — 100,000 BTU, or 29.3 kWh of heat — at about 90% efficiency.
So the space heater loses on price per unit of heat, every time. The only lever it has is volume: it heats one room while the central system heats all of them. Space heaters win when (rooms you heat) ÷ (rooms in your home) is smaller than the ratio of the two heat prices.
Monthly Cost by Rooms Heated
A 5-room home, 8 hours of heating a day, 30-day month, $0.16/kWh. Each room takes one 1,500W heater's worth of heat to hold temperature. Central heat costs the same whether you occupy one room or all 5— that's the flat line the space heaters have to beat.
| Rooms heated | Space heaters | Heat pump (whole home) | Gas furnace (whole home) | Cheapest |
|---|---|---|---|---|
| 1 of 5 | $57.60 | $115.20 | $102.39 | Space heaters |
| 2 of 5 | $115.20 | $115.20 | $102.39 | Gas furnace |
| 3 of 5 | $172.80 | $115.20 | $102.39 | Gas furnace |
| 4 of 5 | $230.40 | $115.20 | $102.39 | Gas furnace |
| 5 of 5 | $288.00 | $115.20 | $102.39 | Gas furnace |
Heat pump at COP 2.5; gas furnace at $1.50/therm and 90% AFUE. Gas prices swing far more than electricity prices, so check your own bill — the calculator above takes your number.
How Much of Your Home Can You Heat Before Central Wins?
Every central system buys heat cheaper than a space heater does. The gap tells you how much of the house you can zone-heat before you've given the advantage back. At the US average rate of $0.16/kWh:
| Central system | Cost per kWh of heat | Share of home | Rooms of 5 |
|---|---|---|---|
| Space heater (the benchmark) | $0.160 | — | — |
| Heat pump (COP 3.5, mild weather)Best case for a modern unit | $0.046 | 29% | 1.4 |
| Heat pump (COP 2.5, typical season)The usual comparison | $0.064 | 40% | 2.0 |
| Heat pump (COP 1.8, freezing weather)Efficiency falls as it gets cold | $0.089 | 56% | 2.8 |
| Gas furnace ($1.00/therm, 90% AFUE)Low gas price | $0.038 | 24% | 1.2 |
| Gas furnace ($1.50/therm, 90% AFUE)Mid gas price | $0.057 | 36% | 1.8 |
| Gas furnace ($2.50/therm, 90% AFUE)High gas price | $0.095 | 59% | 3.0 |
| Electric furnace or baseboardIdentical to a space heater | $0.160 | any | all (a tie) |
“Share of home” is how much of your house you can heat with space heaters before the central system becomes cheaper. Against an electric furnace or baseboards the heat price is identical, so space heaters are never worse — they can only heat less. A gas furnace's share depends on your gas price; a heat pump's falls in freezing weather as its COP drops.
Your Zone Heating Cost by Electricity Rate
The space heater side of the ledger, at 8 hours a day over a 30-day month with 1,500W heaters. Find your state's rate on the electricity rates by state page, then read across.
| Rate ($/kWh) | 1 room | 2 rooms | 3 rooms | Heat pump (whole home) |
|---|---|---|---|---|
| $0.10 | $36.00 | $72.00 | $108.00 | $72.00 |
| $0.13 | $46.80 | $93.60 | $140.40 | $93.60 |
| $0.16 (US avg) | $57.60 | $115.20 | $172.80 | $115.20 |
| $0.20 | $72.00 | $144.00 | $216.00 | $144.00 |
| $0.30 | $108.00 | $216.00 | $324.00 | $216.00 |
Both columns scale with your rate, so the two-room break-even against a COP-2.5heat pump holds at any electricity price. A gas furnace is the exception: its heat price doesn't move with your electricity rate, so the higher your rate, the worse space heaters look next to gas.
What Ruins the Zone Heating Math
Leaving the thermostat where it was
The saving comes entirely from the heat the central system stopsmaking. Run a space heater without turning the thermostat down and you've added $57.60a month to a bill you were already paying. Most people can't drop the setback all the way either — pipes and unoccupied rooms still need some heat — so real-world savings land below the table's numbers.
The second and third heater
Space heaters scale linearly and central heat doesn't. Two heaters cost twice as much; heating the whole house centrally costs the same as always. Against a typical heat pump you cross over at about 2.0 of 5 rooms, and against a gas furnace at roughly 1.8. A heater in the bedroom and another in the office is already the losing side of that trade.
Cold snaps move the line
A heat pump's COP falls as the outdoor temperature drops, and below freezing many units bring in resistance backup heat — at which point the central system is buying heat at the same price a space heater does, but for the whole house. Those are the days zone heating pays off most. A gas furnace's efficiency, by contrast, doesn't care how cold it is outside.
Assuming a better heater will help
It won't. Ceramic, infrared, and oil-filled heaters all draw the same 1,500W on high and all turn essentially 100% of it into heat. What lowers the bill is a lower setting, a thermostat that cycles the heater off, and fewer running hours — see the energy savings guide.
The Verdict
Use a space heater to heat one room, and turn the thermostat down. One heater in the room you occupy, 8 hours a day, runs $57.60 a month — well under the $115.20 it takes to keep a whole 5-room home warm with a heat pump. That is the entire case for space heaters, and it's a good one.
Don't heat a house with them. Past about 2.0 rooms against a heat pump, or 1.8 against a gas furnace, you're paying a premium for every unit of heat and getting nothing back. Electric resistance heat is the most expensive heat in the house — it only wins by making less of it.
If your central system is an electric furnace or baseboards, the heat price is identical and space heaters can only help — they heat less of the house for the same price per kWh.
Related Guides
Cost to Run a Space Heater
Hourly, monthly, and yearly tables for a 1,500W heater
Electricity Rates by State
The rate that decides both sides of this comparison
Cost to Run Central AC
The same whole-home vs. one-room trade, in summer
How to Save on Energy Bills
Sealing drafts cuts heater runtime on either system
Frequently Asked Questions
Is it cheaper to use space heaters than central heat?
Only if you heat a lot less of your home. Per unit of heat, a space heater is the most expensive heat you can buy — electric resistance is 100% efficient at the outlet but delivers just one unit of heat per unit of electricity. A heat pump moves 2.5 units of heat per unit of electricity, so it buys the same heat for about $0.064/kWh against a space heater's $0.16/kWh at the US average rate. Space heaters win only by heating fewer rooms: in a 5-room home, roughly 2.0 rooms against a typical heat pump and 1.8 rooms against a gas furnace. Heat one room and turn the thermostat down and you save; run three heaters and you pay more than central heat.
How much does it cost to heat one room with a space heater?
A 1,500W heater running 8 hours a day costs about $0.24 per hour and $57.60 per month at the US average rate of $0.16/kWh. Holding a whole 5-room home at temperature with a typical heat pump over the same hours costs about $115.20 a month — so zone heating a single room saves roughly $58 a month, provided you actually turn the central thermostat down.
Why is a space heater more expensive than a heat pump if it's 100% efficient?
Because efficiency and cost aren't the same thing. A space heater converts all the electricity it draws into heat — it can't do better than that. A heat pump doesn't make heat, it moves heat from outside air into your home, so it can deliver 2-3.5 units of heat per unit of electricity. Its coefficient of performance (COP) is above 1, which no resistance heater can achieve. That's why the same warmth costs a fraction as much.
Does the number of rooms really decide it?
Yes — it's the whole comparison. Space heaters buy expensive heat but only heat where you are. Central systems buy cheap heat but heat everywhere. The break-even is the ratio of the two heat prices: if a heat pump buys heat at 40% of a space heater's price, space heaters win only when you heat less than 40% of your home.
What ruins the zone heating math?
Three things. First, not turning the central thermostat down — running heaters on top of central heat only adds cost. Second, plugging in a second and third heater, which pushes you past the break-even room count fast. Third, cold snaps: a heat pump's COP falls as the temperature drops, which narrows the gap, while a gas furnace's efficiency doesn't change. You also can't usually let the rest of the house go arctic — most people keep the central system at a low setback for pipes and other rooms, which means you pay for both.
Does an infrared or oil-filled heater cost less to run?
No. Nearly every plug-in heater tops out at 1,500W because that's the safe limit for a 15-amp outlet, and all of them turn essentially 100% of that electricity into heat. Ceramic, infrared, oil-filled, and fan-forced heaters cost the same per hour at the same wattage. What lowers the bill is running a lower setting (often 750W) or letting a thermostat cycle the heater off — not the heating technology.