Cheapest Way to Heat a Room: Cost per Hour, US and UK

Heating 9 min read

By the Plug & Penny editorial team · Published 11 November 2026

The cheapest way to keep yourself warm in one room is an electric blanket. One rated 70 to 150 W costs about 1¢ to 3¢ an hour in the US and 2p to 4p in the UK.

To heat the air in the room, a 1,500 W space heater on high costs about 27¢ (US) or 39p (UK) an hour. Gas central heating, or a heat pump working at a COP of 3 to 4, delivers the same 1.5 kW of heat for roughly a quarter to a third of that: 7¢ to 9¢ an hour in the US and 10p to 14p in the UK.

Heat pumps work less efficiently in very cold weather. At the ENERGY STAR cold-climate minimum, the same heat would cost about 16¢ or 23p an hour. That is still less than the space heater.

Prices used throughout:

• US electricity: 18.16¢/kWh, the national residential average (EIA, August 2026).
• UK electricity and gas: price cap of 26.32p/kWh for electricity and 7.97p/kWh for gas, Great Britain average, Direct Debit (Ofgem, 1 October to 31 December 2026).
• US gas: about 5.05¢ per kWh. This is not an official 2026 price. We could not get an official 2026 US residential gas price. Instead we use the 2025 national average, which converts to roughly $1.48 per therm using EIA's conversion method. One therm is 100,000 Btu and one kWh is 3,412 Btu, so a therm is about 29.3 kWh. That gives $1.48 ÷ 29.3 = 5.05¢ per kWh. Gas prices vary a lot by state and month, so check the price per therm on your own bill.

Cost per hour, side by side

To compare fairly, the table shows the cost of putting 1.5 kW of heat into a room for one hour. That is what a 1,500 W space heater gives on its high setting. Lasko's ceramic heaters, for example, run at 1,500 W on high and 900 W on low.

How big a room that heats depends on insulation. One US electric co-op offers a rough rule of thumb of about 10 W per square foot, which would make 1,500 W enough for about 150 sq ft (14 m²).

The electric blanket rows are different. They warm you, not the room.

These are running costs only. UK standing charges and US fixed fees are left out, because you pay them whichever option you use. The US gas rows use the 2025-based 5.05¢/kWh explained above.

How we worked it out

For electricity: watts × hours ÷ 1,000 = kWh, then kWh × price = cost. A 1,500 W heater running for one hour uses 1,500 × 1 ÷ 1,000 = 1.5 kWh. In the US that is 1.5 × 18.16¢ = 27.24¢. In the UK it is 1.5 × 26.32p = 39.48p.

Electric resistance heaters are considered 100% efficient, so 1.5 kWh of electricity gives 1.5 kWh of heat. That is according to a US Department of Energy guide republished by the Missouri Department of Natural Resources.

A heat pump moves heat rather than making it, so you divide the heat by its COP (heat out per unit of electricity in). At COP 3, 1.5 kWh of heat needs 0.5 kWh of electricity. That costs 0.5 × 18.16¢ = 9.08¢ in the US, or 0.5 × 26.32p = 13.16p in the UK.

For gas, divide the heat by the boiler or furnace efficiency, then multiply by the gas price. A UK boiler at 92% needs 1.5 ÷ 0.92 = 1.63 kWh of gas, and 1.63 × 7.97p = 13p. A US furnace at 95% needs 1.5 ÷ 0.95 = 1.58 kWh of gas, and 1.58 × 5.05¢ = 8¢.

Where the efficiency figures come from

• Heat pumps: the Energy Saving Trust says a heat pump gives three to four times as much heat as the electricity it uses (COP 3 to 4). The COP 1.75 row is the ENERGY STAR cold-climate minimum at 5°F, a worst case for a certified cold-climate unit. The mini-split row is explained in the heat pump section below.
• US gas furnaces: the federal minimum for most gas furnaces is 80% AFUE. A DOE rule sets 95% for furnaces made from December 18, 2028. DOE says condensing furnaces reach 90% to 98%.
• UK gas boilers: new boilers must be A-rated with at least 92% efficiency. Which? notes they do not get over 90% in every home, so we also show 85% as a conservative real-world figure.

Daily and monthly costs for heaters and blankets

These tables assume 8 hours a day and 30 days a month. For blankets, 8 hours is the overnight use that EDF and Uswitch both use in their examples.

We do not show a yearly figure, because nobody heats a room all year. Multiply the monthly cost by the number of months you heat.

The wattages are maximum ratings. Heaters with thermostats switch on and off once the room is warm, so real costs are usually lower. We found no measured data on how much lower.

United States (18.16¢/kWh, EIA, August 2026)

United Kingdom (26.32p/kWh, Ofgem, 1 October to 31 December 2026)

Where the wattages come from:

• 1,500 W and 900 W: the high and low settings on Lasko ceramic heaters such as the 754200.
• 700 W: the minimum setting of the UK De'Longhi Radia S, which tops out at 1,500 W.
• 70 W and 150 W: EDF's typical blanket and the top of its 40 to 150 W range.
• 300 W: the most Uswitch says most blankets use on their highest setting.

To work out your own heater, hours and price, use the calculator. UK readers should switch it to the UK or enter 26.32p/kWh.

Space heater vs central heating: which is cheaper?

Unit for unit, central heating wins. One kWh of heat from a space heater costs the same as one kWh of electricity: 18.16¢ in the US and 26.32p in the UK.

For gas, divide the price of a kWh of gas by the efficiency to get the cost of a kWh of heat:

• US, 95% furnace: 5.05¢ ÷ 0.95 = 5.32¢ per kWh of heat.
• US, 80% furnace: 5.05¢ ÷ 0.80 = 6.31¢ per kWh of heat.
• UK, 92% boiler: 7.97p ÷ 0.92 = 8.66p per kWh of heat.
• UK, 85% boiler: 7.97p ÷ 0.85 = 9.38p per kWh of heat.

So heat from a space heater costs roughly three times as much as gas heat in both countries. A heat pump at COP 3 is similar to gas: 18.16¢ ÷ 3 = 6.05¢, or 26.32p ÷ 3 = 8.77p, per kWh of heat. Remember the US gas figures rest on the 2025-based price above, not an official 2026 one.

The DOE guide republished by the Missouri DNR calls electric resistance heating the most expensive form of heating. Uswitch says electric heaters are less cost-effective than gas or oil central heating and are designed for small spaces.

The catch is that central heating warms the whole house, not one room. A space heater can still save money if it lets you heat far less space. The same DOE guide says turning the central heating down a few degrees while you use a space heater will probably save money. A US co-op magazine makes the flip side clear: a heater running on top of unchanged central heating raises the bill.

We found no official figure for the break-even point. It depends on the size of your home, its insulation and how far you turn the thermostat down. Your own bills are the best guide. Compare a month with the heater on and the thermostat down against a similar month without.

Electric blanket vs heater

If you only need to keep yourself warm, nothing here comes close to an electric blanket. A 150 W blanket uses a tenth of the power of a 1,500 W heater.

Sources give different ranges:

• EDF lists most blankets, throws and underblankets at 40 to 150 W and uses 70 W as its typical example.
• Electrical Safety First says blankets typically draw 60 to 100 W in use.
• Uswitch puts the top end higher. It says most are rated 100 to 300 W, with some single blankets as low as 40 W.

The gap is mostly size and settings. Bigger blankets sit at the top of the range, and the rating is the most a blanket draws on full power. Even a 300 W blanket on full power costs about 5¢ an hour in the US (0.3 × 18.16¢) or 8p in the UK (0.3 × 26.32p). Uswitch says energy use falls significantly on the lowest setting.

The trade-off is that a blanket warms your bed or your lap, not the air. It suits sleeping or sitting still on the sofa. For a home office where you move around, you still need some room heat.

Heat pumps for one room

A ductless mini-split can heat one room for much less than a space heater. As one example, Mitsubishi's own submittal sheet for the MSZ-FS09NA (the copy we found is hosted by a retailer, AC Direct) rates the unit at 9,600 BTU/h of heat for 620 W of electricity at 47°F outdoors.

That is 9,600 ÷ 3,412 = 2.8 kW of heat, and 2.8 ÷ 0.62 gives a COP of about 4.5. Running at that rating uses 0.62 kWh an hour. That costs 0.62 × 18.16¢ = 11¢ an hour in the US, or 0.62 × 26.32p = 16p in the UK.

Note that 11¢ or 16p buys 2.8 kW of heat, nearly twice what a 1,500 W space heater gives out. To compare on the same basis as the side-by-side table, scale it to 1.5 kW: 1.5 ÷ 4.5 = 0.33 kWh of electricity, which costs about 6¢ (US) or 9p (UK) an hour. The space heater costs 27¢ or 39p for that same 1.5 kW.

Treat this as a best case, not a typical figure. 47°F is a mild rating point, and efficiency falls as it gets colder outside. That is why the side-by-side table also shows COP 1.75, the ENERGY STAR cold-climate minimum at 5°F.

Real-world results can also fall short of headline figures. An older Energy Saving Trust field trial of UK air source heat pumps found average seasonal performance of 2.45 to 2.68. The data is more than five years old. At 2.45, 1.5 kW of heat would need 0.61 kWh of electricity, about 11¢ (US) or 16p (UK) an hour. That is still well under a space heater.

When comparing models, ENERGY STAR certified mini-splits need at least 7.8 HSPF2, or 8.5 for the cold-climate label. Higher is better.

We have no official installation cost data, so we cannot say whether one pays back for your room. A heat pump is a big decision, so get quotes from qualified installers and compare them with what you pay now.

How to cut the cost

• Turn the main thermostat down when you heat one room. A space heater only saves money if the rest of the house gets less heat.
• Set back the thermostat. DOE says turning it back 7 to 10°F for 8 hours a day can save as much as 10% a year on heating and cooling. The same page notes that programmable thermostats have generally not been recommended for heat pump systems.
• UK: use proper controls. The Energy Saving Trust says boiler systems should have at least a programmer, a room thermostat and thermostatic radiator valves (TRVs). TRVs let you heat only the rooms you use. It estimates good controls could save around £100 a year in Great Britain. Fitting all three costs around £600, or around £370 for TRVs alone if you already have the other two.
• Use the heater's thermostat and low setting. A 900 W setting costs 40% less per hour than 1,500 W.
• Warm the bed, then switch off. Uswitch suggests full heat for 10 to 15 minutes before bed, then off.

Stay safe

Keep a space heater at least 3 feet (1 meter) from anything that can burn. Plug it straight into a wall outlet, never an extension cord or power strip, and turn it off when you sleep. That advice comes from the CPSC in the US and Electrical Safety First in the UK.

For electric blankets, Electrical Safety First recommends replacing them every ten years, or sooner if you see wear, scorch marks or damaged cords. It also recommends unplugging the blanket when you get into bed. If you leave it on overnight, it needs temperature controls, automatic shut-off and overheat protection.

Sources

1. Electric Power Monthly, Table 5.6.A (EIA)
2. Energy price cap unit rates and standing charges (Ofgem)
3. How do I convert natural gas prices in dollars per cubic feet to dollars per British thermal unit or therm? (EIA)
4. British thermal units (Btu) (EIA)
5. Lasko 1500W Electric Ceramic Space Heater with Adjustable Thermostat 754200
6. Can a portable electric space heater help cut your winter heating bills? (Illinois Electric Cooperative)
7. Space Heaters - PUB2849 (Missouri DNR, republishing a US DOE Energy Savers guide)
8. Heat pumps: how they work, costs and savings (Energy Saving Trust)
9. Heat Pump Equipment Key Product Criteria (ENERGY STAR)
10. Energy Conservation Program: Energy Conservation Standards for Consumer Furnaces (Federal Register)
11. Incorporate Minimum Efficiency Requirements for Heating and Cooling Products into Federal Acquisition Documents (US DOE FEMP)
12. Boiler energy efficiency explained (Which?)
13. Radia S Oil filled radiator 1.5KW TRRS0715 (De'Longhi UK)
14. Are electric blankets expensive to run? (EDF)
15. How much does an electric blanket cost to run? (Uswitch)
16. Energy-efficient heaters (Uswitch)
17. Electrical Safety Advice for Electric Blankets (Electrical Safety First)
18. MSZ-FS09NA & MUZ-FS09NA submittal (Mitsubishi Electric spec sheet, hosted by AC Direct)
19. The heat is on: heat pump field trials phase 2 (Energy Saving Trust)
20. Home Upgrades (US Department of Energy)
21. Heating controls (Energy Saving Trust)
22. Keep Warm and Safe This Winter: Tips for Using Generators, Furnaces and Space Heaters (CPSC)
23. Electrical Safety Advice for Portable Heaters (Electrical Safety First)

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