Heating, cost per kWh of heat
Cost per kWh of heat: gas, electric, wood and heat pump
A gas boiler, a plug in electric heater, a wood stove and a heat pump all buy fuel at a different price, and every one of them wastes some of it before it becomes warmth. Cost per kWh of fuel bought is not cost per kWh of heat delivered, and the gap between the two is where a heat pump earns its keep and where a wood stove quietly loses the argument its own marketing makes.
Some links on this page are affiliate links, which earn us a commission if you buy. It costs you nothing extra, and it never changes which option comes out cheapest here, because the ranking is arithmetic. How this works.
Efficiency is the hidden second price
The unit rate on a bill is only half the sum. What matters for a warm room is fuel price divided by how much of that fuel a system actually converts to heat. A gas boiler and a heat pump both lose very little of what they consume; a wood stove loses noticeably more, up the flue and into its own casing; a plug in electric heater loses nothing at all and still costs the most, because it starts from the dearest fuel on the site and has no efficiency left to spend.
| Option | Running | Cost per kWh of heat | Relative |
|---|---|---|---|
| Gas boilercondensing, about 90% efficient | 8.14p | 8.14p | |
| Air source heat pumptypical UK install, SCOP around 3 | 8.7p | 8.7p | |
| Wood stove, seasoned logs in bulkloose cubic metre, delivered | 8.85p | 8.85p | |
| Wood stove, kiln-dried netssupermarket or garage forecourt | 20.2p | 20.2p | |
| Plug in electric heaterpanel, fan or convector, 100% efficient | 26.1p | 26.1p |
The gas boiler delivers a kWh of heat for 8.14p, and the plug in electric heater costs 26.1p for the same kWh, a factor of 3.2. The genuinely interesting result is in the middle: a heat pump and a stove burning bulk bought logs land within a fraction of a penny of each other, and both sit close behind gas rather than far behind it.
Gas is not slightly cheaper, but a heat pump is close
Gas wins outright because its fuel price is so far below everything else that even electricity's efficient uses cannot close the gap. A heat pump is the one electric option that gets near it, and the reason is entirely the SCOP: three kilowatt hours of heat for one bought is enough to turn the dearest fuel on this site into something that costs almost the same as the cheapest one. A resistive heater run on the same electricity, with no multiplier, ends up the most expensive thing in the table.
Where the working comes from
The wood rows need one extra step the others do not. Gas and electricity arrive already priced per kWh; wood is sold by the cubic metre or by the net, so it has to be weighed and converted before it can be compared with anything. Both conversions are below, and both are the reason a stove can look cheap or dear depending only on how you bought the same logs.
UK retail prices for a loose cubic metre run roughly £70 to £120 depending on region and how far ahead you order; priced here at £85, the middle of that range. A loose cubic metre of stacked hardwood logs weighs approximately 320kg, and seasoned hardwood at around 20% moisture content has a net calorific value of approximately 4.0 kWh per kg. 85 / (320 x 4.0) = 6.64p per kWh of wood bought, before any stove loses heat up the flue.
Nets work out to roughly £0.60 to £0.70 per kg once weighed against their contents; priced here at £0.65. Kiln drying takes moisture lower than seasoning alone, giving a net calorific value of approximately 4.3 kWh per kg. 0.65 / 4.3 = 15.12p per kWh of wood bought, before any stove loses heat up the flue.
Both sums are the same shape: a fuel price divided by an efficiency. The only thing that differs between every row in this table is which fuel and which fraction, and both numbers are stated in the working rather than folded into the headline figure.
The wood answer swings on how you buy it
This is the row worth reading twice. Buy seasoned hardwood loose by the cubic metre and a stove costs 8.85p a kWh delivered, close enough to gas and a heat pump that the honest description is a tie inside the uncertainty of the wood price itself, not a saving. Buy the same wood as kiln-dried nets from a supermarket, a garage or a DIY store, which is how most people without room to store a bulk load actually buy it, and the price of the wood alone more than doubles the delivered cost to 20.2p, dearer than gas by a wide margin.
A loose cubic metre of seasoned hardwood retails anywhere from about £70 to £120 in the UK, and this page prices it at £85, the middle of that range. At the cheap end wood undercuts gas; at the dear end it does not, and nothing about the stove changes that. The only lever a buyer has is what they pay per cubic metre. Free, scrounged, already-dry wood beats every fuel here outright, because it has no price to divide.
The verdict
Heat with gas wherever the choice exists; nothing here gets close enough to change that. Where gas is not an option, a heat pump is the electric route that actually competes, because the SCOP does the work a resistive heater cannot. A wood stove is only cheaper than gas if the wood is free or bought well at the bottom of the market; bought as most people actually buy it, by the net rather than the cubic metre, it is comfortably the dearer choice of the two fuels that are supposed to compete with gas, and a plug in heater never competes with anything on this page.
Put your own numbers in
Every other page on this site prices a kilowatt hour of fuel. This one prices a kilowatt hour that actually reaches the room, which is a different number for every system here.
Cost per meal
Set the purchase price to zero for the running cost alone.
Questions
What is the cheapest way to heat a room per kWh?
Mains gas, by a wide margin, at 8.14p a kWh of heat actually delivered. A heat pump is the closest electric option at 8.7p, because its SCOP multiplies every kWh of electricity bought into roughly three kWh of heat.
Is a wood burning stove cheaper than gas?
Only if the wood is free or bought well. Seasoned logs bought loose by the cubic metre come out close to gas, 8.85p against 8.14p, essentially a tie given how much the wood price itself varies. Bought as kiln-dried nets, the more common way to buy wood without storage for a bulk load, it costs 20.2p, well above gas.
How efficient is a heat pump compared to a gas boiler?
A heat pump does not burn fuel, it moves heat, and a typical UK installation delivers around three kWh of heat for every kWh of electricity bought. A condensing gas boiler converts about 90% of the gas it burns. Because gas itself is so much cheaper than electricity per kWh, the boiler still wins on cost even though the heat pump is the more efficient machine.
Why is a plug in electric heater the most expensive way to heat a room?
Because it converts essentially all of its electricity to heat and still loses. It starts from the dearest fuel on this site, 26.11p per kWh, and has no efficiency multiplier left to spend the way a heat pump does, so nothing offsets the fuel price.
Does a more efficient boiler always mean cheaper heat?
Efficiency only matters multiplied by the fuel price. A 90% efficient gas boiler beats a 100% efficient electric heater because gas costs a fraction of what electricity costs per kWh; the efficiency gap between them is small next to the fuel price gap.
Related
- What a kWh really costs, once the standing charge is inThe capped unit rate is not what you pay per kWh. Add the standing charge and a low user pays half again what a high user does.
- Cost per cut: petrol, electric and manual mowersWhat a UK lawn actually costs to cut with a petrol, corded electric or manual mower, purchase price and fuel both included, at August 2026 prices.
- Air fryer running cost vs oven, per mealWe cost an air fryer against an electric fan oven per meal at the August 2026 UK price cap, and find the batch count where the oven wins.
More heating and damp costs, or read how we work these out.
Prices used on this page
- Electricity, 26.11p per kWh. Ofgem price cap, direct debit, average of England, Scotland and Wales, including 5% VAT.. Ofgem energy price cap unit rates and standing charges. Checked 22 August 2026.