Cheapest Heater to Run: Full Cost Comparison

You’ve just opened your winter electricity bill and felt your stomach drop. The numbers don’t lie — heating a single room with a tiny plug-in heater cost you more than your entire weekly grocery run. You’re not alone. Most people pick a heater based on how fast it warms up or how quiet it runs, not on what it actually costs per hour. That’s a mistake that adds up fast.

This guide breaks down the real running costs of every major heater type — electric, gas, storage, halogen, oil-filled, and heat pumps. You’ll learn the exact math to calculate cost per hour, see a direct comparison table, and understand why insulation and thermostat habits matter more than the heater itself. By the end, you’ll know exactly which type of heater is cheapest to run for your specific room and situation.

If you’re looking for a portable electric option that balances cost and comfort, the DREO Space Heater is a solid pick. It uses a 1500W PTC ceramic system with a thermostat that lets you dial in temperatures from 41–95°F in 1-degree increments, so you’re not wasting energy overheating an empty room. The ECO mode and 12-hour timer help keep running costs down, and it’s quiet enough for a bedroom.

The Short Answer: Which Heater Wins?

If you have access to mains gas, a flued gas space heater is the cheapest way to heat a single room — period. Gas costs roughly a third of the price of electricity per unit of heat in most regions. A heat pump (reverse-cycle air conditioner) comes in second, especially in milder climates, because it moves heat instead of creating it.

But here’s the twist: most people don’t have a gas line running into their living room. If you’re stuck with electric, the cheapest option isn’t the heater type — it’s the one with the lowest wattage that still meets your needs, paired with a thermostat and timer. A 700W oil-filled radiator running for hours will cost less than a 2000W fan heater running for 20 minutes, even though the fan heater feels cheaper because it’s on for less time.

For pure electric resistance heating, all types (fan, convector, halogen, oil-filled) produce exactly 1 unit of heat per 1 unit of electricity. The difference is how they deliver that heat and whether you can control it precisely. That’s where the real savings live.

How to Compare Running Costs (The Math)

The Formula: Watts, Hours, and Your Tariff

Every heater has a wattage rating — typically 500W, 1000W, 1500W, or 2000W. The formula is simple:

Cost per hour = (Wattage ÷ 1000) × cost per kWh

Let’s use a real example. Your electricity tariff is 30p per kWh (typical UK rate under the energy price cap). A 1500W heater costs:

(1500 ÷ 1000) × 30p = 45p per hour

Run that heater 8 hours a day for a month, and you’re looking at £108. That’s not a typo. A 2000W heater at the same rate costs 60p per hour, or £144 a month. The wattage difference between 1500W and 2000W is just 500W, but it adds up to £36 a month.

For gas, the math is different. Gas costs about 7p per kWh (again, UK average). A gas heater with 80% efficiency uses more gas per unit of heat, but the fuel is so much cheaper that it still wins. Roughly:

(2 kWh of gas input ÷ 0.8 efficiency) × 7p = 17.5p per hour for 2kW of heat output

That’s about a third of the electric cost. This is why the answer to which type of heater is cheapest to run always points to gas first, if it’s available.

Why “Efficiency” is Misleading

You’ll see electric heaters advertised as “100% efficient.” That’s technically true — every watt of electricity becomes heat. But it’s also meaningless. A heat pump can deliver 300% efficiency because it extracts heat from the outside air. It uses 1 unit of electricity to move 3 units of heat into your room.

So when comparing heaters, ignore the efficiency percentage. Focus on cost per unit of heat delivered. Electric resistance is always 1:1. Heat pumps are 1:3 or better. Gas is cheap fuel with some waste. That’s the whole story.

The Cost Breakdown: Every Heater Type Ranked

Here’s the table you actually need. It assumes a UK energy price cap of 30p/kWh for electricity and 7p/kWh for gas. Adjust the numbers for your local tariff.

Heater Type	Typical Wattage	Cost per Hour (approx.)	Heat Delivery	Best For
Heat Pump (reverse-cycle AC)	900W input (produces ~3kW heat)	27p	Whole room, fast	Mild climates, long running times
Gas Space Heater (flued)	2kW output	17p	Whole room, fast	Homes with gas lines, living areas
Gas Space Heater (unflued)	2kW output	15p (plus ventilation losses)	Whole room, very fast	Well-ventilated rooms, occasional use
Storage Heater (off-peak)	2kW (charging overnight)	14p (at 10p/kWh off-peak)	Slow release, steady	Homes on Economy 7 tariffs
Oil-Filled Radiator	1500W	45p	Slow, radiant + convection	Bedrooms, overnight use
Convector Heater	2000W	60p	Fast, convection	Quick warm-ups, small rooms
Fan Heater	2000W	60p	Very fast, forced air	Emergency heat, short bursts
Halogen Heater	400W – 1200W	12p – 36p	Instant radiant heat	Spot heating, one person
Portable LPG Heater	4.2kW output	~50p (at £1.50/kg gas)	Very fast, intense	Garages, workshops, no electric

Notice the pattern: anything that creates heat from electricity costs roughly the same per unit. The savings come from using less heat — lower wattage, better targeting, or off-peak tariffs.

Reverse-Cycle Air Conditioners (Heat Pumps)

Heat pumps are the quiet champion of the heating world. They cost more upfront (often £500–£1500 installed), but they deliver 2.5 to 4 units of heat for every unit of electricity. That makes them cheaper to run than any electric resistance heater, and often cheaper than gas in mild weather.

The catch? They stop being efficient below about 5°C outside. In freezing temperatures, the efficiency drops toward 1:1, and they become just another electric heater. They’re also overkill for a small bedroom if you only need heat for an hour a day.

Gas Space Heaters (Flued & Unflued)

Gas is the cheapest fuel per kWh, but installation costs are real. A flued gas heater needs a chimney or wall vent, which means a professional install. Unflued models (like the Mr Heater Buddy) are portable but release moisture and carbon monoxide — they need ventilation, which also lets heat escape.

If you already have a gas line and a flue, this is the lowest running cost option for a single room. If you don’t, the installation cost might take years to recoup in fuel savings.

Electric Heaters (Convection, Fan, Oil-Filled, Radiant)

All electric resistance heaters cost the same per kWh. The difference is control and comfort. A fan heater blasts hot air, warms the room in 5 minutes, but then you turn it off and the heat vanishes. An oil-filled radiator takes 30 minutes to warm up but radiates heat for another 30 minutes after you switch it off. That residual heat is free — and it’s why oil-filled radiators often feel cheaper in practice.

Halogen heaters are the cheapest to run by wattage (some are only 400W), but they only heat what’s directly in front of them. You’ll sit in a warm spot while the rest of the room stays cold. That’s fine for one person at a desk, not for a family room.

For a portable electric option, the DREO Space Heater offers a 1500W PTC system with a thermostat that cycles on and off to maintain your set temperature. That cycling is where the savings come from — it’s not blasting full power the whole time.

Portable LPG & Kerosene Heaters

These are the outliers. LPG costs about £1.50 per kg, and a 4.2kW heater burns roughly 0.3 kg per hour, so around 50p per hour. That’s comparable to electric, but with the added cost of ventilation heat loss and the hassle of refilling bottles. Kerosene is similar. These make sense for workshops and garages where electric isn’t practical, not for living spaces.

The Hidden Variable: Insulation and Room Size

Here’s a truth the heater manufacturers don’t advertise: the cheapest heater is the one you don’t need to run. If your room loses heat faster than the heater can add it, you’ll burn through electricity no matter what type you buy.

A room with single-glazed windows and no loft insulation can lose 30–40% of its heat through the walls and windows. That means a 2000W heater might run continuously just to maintain 20°C. The same room with draft-proofing and thick curtains might only need the heater on for 20 minutes every hour. That’s a 60% reduction in running costs — bigger than any heater type difference.

Room size matters too. A 2000W heater in a 10m² bedroom will cycle on and off, averaging maybe 800W of actual consumption. The same heater in a 30m² open-plan living area will run flat out the whole time, consuming the full 2000W. The heater didn’t change — the heat loss did.

Before you buy any heater, fix the obvious leaks. Draft excluders, thermal curtains, and a roll of insulation tape cost less than one month of wasted heating.

Smart Thermostats and Zoning: Cutting Costs Further

Most people run their heater on full power until the room feels warm, then switch it off. Then the room cools down, they switch it back on, and the cycle repeats. That’s the most expensive way to heat a room.

A thermostat changes the game. Set it to 19°C instead of 22°C and you’ll cut your heating bill by roughly 10% for every degree you drop. A heater with a built-in thermostat, like the DREO with its NTC chipset, maintains the temperature without you thinking about it. The heater runs at full power until it hits 19°C, then drops to a low maintenance level or switches off entirely.

Timers are the other half of the equation. Set the heater to turn off 30 minutes before you leave for work, and on 30 minutes before you get home. You’ll never heat an empty room again. Smart plugs with scheduling do the same job for older heaters without built-in timers.

Zone heating — heating only the room you’re in — is almost always cheaper than whole-house central heating. A 1500W heater running for 3 hours in the evening costs 45p per hour × 3 = £1.35. A gas boiler heating the whole house for the same 3 hours might cost £2–£3. If you live alone or work from home in one room, zone heating wins.

The Real Cost of Ownership: Maintenance and Safety

Running costs are only half the story. A cheap heater that breaks after one season, or a gas heater that needs annual servicing, can wipe out any fuel savings.

Electric heaters have almost no maintenance. There’s nothing to service, no flue to clean, no gas line to check. They last 5–10 years with zero upkeep. Just dust the fins and check the cord occasionally.

Gas heaters need annual servicing. A flued gas heater requires a professional inspection, typically £80–£150 per year. Unflued models need regular cleaning of the burner and a carbon monoxide detector — which you should have anyway. These costs add up, so factor them into your cost-per-hour calculation.

Heat pumps need a filter clean every few months and a professional service every 2–3 years. The filter cleaning is a 10-minute job you can do yourself, but the service costs £100–£200.

Storage heaters are the maintenance nightmare. The bricks inside can crack, the casing can rust, and the internal wiring can degrade. Repairs are often not worth the cost — many people replace them entirely after 10–15 years.

Also consider lifespan. A £30 fan heater that dies after one winter isn’t cheaper than a £100 oil-filled radiator that lasts 10 years. Divide the purchase price by the expected lifespan to get the true annual cost.

The Verdict: The Cheapest Way to Heat One Room

Let’s rank the realistic options for a typical 15m² living room, assuming 4 hours of heating per day over a 5-month winter:

1. Heat pump — cheapest long-term if you can afford the install. Around £64 for the season.
2. Gas space heater (flued) — £41 for the season, plus £100 servicing. Best if the line already exists.
3. Storage heater on off-peak tariff — £34 for the season, but you need an Economy 7 meter and good insulation.
4. Oil-filled radiator with thermostat — £108 for the season. Simple, safe, no install.
5. Fan heater — £144 for the season. Fast but expensive to run continuously.
6. Halogen heater — £30–£80 for the season, but only heats one person, not the room.

The absolute cheapest is a 400W halogen heater aimed directly at you, but it’s not really heating the room. For actual room heating, gas or a heat pump wins on cost. For electric-only households, an oil-filled radiator or a 1500W PTC heater with a good thermostat is your best balance of cost and comfort.

If you’re in a small bedroom or office, a low-wattage heater (500–800W) with a thermostat will almost always be cheaper than a 2000W heater that cycles on and off. The lower wattage means gentler warm-up but much lower running costs over hours.

Frequently Asked Questions

Which type of heater is cheapest to run?

Gas space heaters are cheapest per unit of heat, followed by heat pumps. For electric-only options, a storage heater on an off-peak tariff is cheapest, then oil-filled radiators with thermostats. The most expensive are fan heaters and convector heaters running at full wattage.

How much does it cost to run a 1500 watt heater for 24 hours?

At 30p/kWh, a 1500W heater running flat out for 24 hours costs (1.5 kW × 30p) × 24 = £10.80. With a thermostat, the heater will cycle on and off, so the actual cost is typically 40–60% of that — around £4–£6. This is why thermostat control matters more than the heater type.

Are oil filled radiators cheaper to run than fan heaters?

At the same wattage, no — they cost exactly the same per hour. But oil-filled radiators retain heat after switching off, so they can be turned off earlier. They also work better with thermostats because they don’t overshoot the target temperature. In practice, you’ll use fewer hours, so the bill is lower.

Is it cheaper to use a gas heater or an electric heater?

Gas is roughly 3–4 times cheaper per unit of heat. A 2kW gas heater costs about 17p per hour versus 60p for a 2kW electric heater. However, gas heaters need installation, ventilation, and annual servicing, which can offset the savings for occasional use.

What is the most energy efficient heater for a small room?

For a small room (under 10m²), a 500–800W oil-filled radiator with a thermostat is the most efficient choice. It heats slowly but steadily, and the thermostat prevents energy waste. A heat pump is more efficient per unit of electricity, but it’s overkill for a small space and the upfront cost is hard to justify.

Do halogen heaters use a lot of electricity?

Halogen heaters are usually 400–1200W, so they use less electricity per hour than a 2000W fan heater. A 400W halogen costs about 12p per hour. But they only heat what’s directly in front of them — the rest of the room stays cold. For spot heating one person, they’re cheap. For heating a room, they’re ineffective.

How can I reduce the cost of running an electric heater?

Lower the thermostat by 1–2 degrees. Use a timer to avoid heating empty rooms. Seal drafts around windows and doors. Heat only the room you’re in. Use a lower wattage heater for small spaces. And always use a heater with a thermostat — the cycling saves 30–50% compared to running at full power.

Are storage heaters cheaper than electric radiators?

Only if you’re on an off-peak tariff like Economy 7. They charge overnight at a lower rate (around 10p/kWh) and release heat during the day. If you’re on a standard tariff, storage heaters cost the same as any electric heater — and they’re harder to control. Check your tariff before buying one.

What is the cheapest way to heat a single room?

If you have gas, a flued gas heater wins. If not, the cheapest electric approach is a low-wattage (500–800W) oil-filled radiator with a thermostat, combined with good insulation and a timer. For one person in one spot, a 400W halogen heater is cheapest but only heats a small area.

How do I calculate the running cost of a heater?

Divide the wattage by 1000 to get kilowatts. Multiply by your cost per kWh (check your electricity bill). That gives you cost per hour at full power. Then multiply by the number of hours you run it. For a realistic estimate, assume the heater runs at 60–70% duty cycle if it has a thermostat.

What Actually Matters: Practical Steps to Cut Your Bill

You now know the math, the rankings, and the trade-offs. Here’s what to do with it:

• Check your electricity tariff first. If you’re paying more than 30p/kWh, every heater costs more than the averages above.
• Buy a heater with a thermostat — not just high/low/off. The thermostat pays for itself in one winter.
• Match the wattage to the room. 1500W for a bedroom, 2000W for a living room, 500W for a study.
• Use a timer or smart plug. Heat the room 30 minutes before you need it, not all day.
• Fix drafts before you buy anything. A £10 draft excluder saves more than a £200 heater upgrade.
• Consider a heat pump or gas heater if you’re heating the same room every day for months. The upfront cost is worth it.
• For portable electric heat, look for a PTC ceramic heater with ECO mode — it modulates power based on the temperature gap, which cuts running costs compared to a fixed 1500W output.

The cheapest heater isn’t a type — it’s a system. Low wattage, tight temperature control, and a room that doesn’t leak heat. Get those three right, and you’ll cut your winter bill by 40% or more, regardless of which box you plug in. For more on heater comparisons, check out this propane heater comparison or this room heater health guide.