Heat Pump Running Costs vs a Gas Boiler: The Real Comparison

Will a heat pump cost more or less to run than a gas boiler? You will find confident answers in both directions online, but the truthful answer is: it depends on how efficient your heat pump turns out to be. Electricity costs several times more per unit than gas, and a heat pump has to work hard enough to overcome that gap. In this guide we show the full working, using current capped prices, so you can see exactly where the tipping point is — and why good design matters more than any headline claim.

The two numbers that decide everything

Under the Ofgem price cap for October to December 2026, a household on a standard variable tariff paying by Direct Debit pays on average 26.32p per kWh for electricity and 7.97p per kWh for gas. Electricity, in other words, costs about 3.3 times as much per unit as gas. For more on how the cap works, see our guide to the energy price cap explained.

That price gap is the whole challenge. What matters is not the cost of a unit of fuel, but the cost of each unit of heat delivered into your rooms — and that is where efficiency comes in.

Efficiency: boilers versus heat pumps

A modern condensing gas boiler converts roughly 90% of the gas it burns into useful heat; the rest is lost. Older boilers do worse, sometimes much worse. So each kWh of heat from a modern boiler actually requires about 1.11 kWh of gas.

A heat pump does not burn anything. It moves heat from the outside air into your home, so it delivers more heat than the electricity it consumes. This is measured by its SCOP — the seasonal coefficient of performance — which is the average efficiency across a whole heating season. A SCOP of 3 means that, on average, 1 kWh of electricity delivers 3 kWh of heat: an efficiency of 300%. Well-designed systems in UK homes commonly achieve a SCOP of around 3 to 3.5, while poorly designed systems, or ones forced to run at high temperatures, can fall to 2.5 or below.

The maths, step by step

Cost per kWh of heat from a gas boiler:

7.97p ÷ 0.90 = 8.86p per kWh of heat

Cost per kWh of heat from a heat pump:

26.32p ÷ SCOP

That gives:

• SCOP 2.5: 10.53p per kWh of heat — more expensive than gas
• SCOP 3.0: 8.77p per kWh of heat — roughly the same as gas, very slightly cheaper
• SCOP 3.5: 7.52p per kWh of heat — clearly cheaper than gas

The break-even point is a SCOP of about 3.0. Your heat pump needs to average roughly three units of heat for every unit of electricity across the season just to match a modern gas boiler on a standard capped tariff. That is achievable, and good installations beat it — but it is not automatic, and anyone who tells you a heat pump is guaranteed to be cheaper is skipping this sum.

What that means over a year

Take a home that needs 10,000 kWh of heat over a year for space heating — a reasonable illustration for a typical three-bedroom house, although your own home could need more or less:

• Gas boiler at 90% efficiency: about 11,100 kWh of gas, costing roughly £886 a year
• Heat pump at SCOP 2.5: about 4,000 kWh of electricity, costing roughly £1,053 a year
• Heat pump at SCOP 3.0: about 3,330 kWh of electricity, costing roughly £877 a year
• Heat pump at SCOP 3.5: about 2,860 kWh of electricity, costing roughly £752 a year

These figures cover the energy used for heating only. They exclude standing charges and hot water, and they assume both systems run on capped standard variable rates. They are illustrations, not predictions for your home.

Standing charges: a genuine extra saving

If you remove your gas boiler entirely, you can have your gas meter removed too, which ends the gas standing charge. At the current cap that charge is 29.68p a day, or about £108 a year. You will still pay the electricity standing charge, which you were paying anyway. That saving does not show up in the per-unit maths above, but it is real money off your annual bill, and for a heat pump running at around SCOP 3 it can be the difference between matching gas and beating it. Our guide to standing charges explained covers how these daily charges work.

How to make a heat pump cheaper to run

Get the design right

Efficiency is decided largely at installation. Heat pumps are most efficient at low flow temperatures — the temperature of the water sent to your radiators. Larger radiators or underfloor heating let the system run cooler and push the SCOP up. An installer who designs for a low flow temperature, based on a proper heat loss survey, is giving you lower bills for the life of the system.

Consider a heat pump tariff

The comparison above uses the standard capped rate, but several suppliers now offer dedicated heat pump or time-of-use tariffs with cheaper electricity at certain times. Because a heat pump runs steadily rather than in short bursts, it can take advantage of cheaper periods, and moving off the standard tariff can shift the comparison firmly in the heat pump’s favour. Tariff terms change often, so compare current offers carefully rather than relying on any figure quoted here.

Insulate first

Every unit of heat your home does not lose is a unit you do not pay for, whichever system you have. Better insulation also lets a heat pump run at lower temperatures, improving its SCOP. Our article on whether heat pumps work in old houses explains the relationship between insulation, radiators and efficiency.

So which is cheaper?

On a standard capped tariff, a well-designed heat pump should cost about the same as, or a little less than, a modern gas boiler to run — and clearly less once the saved gas standing charge is counted. A poorly designed one can cost more. Against an old, inefficient boiler, or in a home currently heated by oil, LPG or direct electric heating, the case is usually much stronger. Carbon emissions are lower in every scenario, because a heat pump moves heat rather than burning fuel, and the electricity grid continues to get cleaner.

Upfront cost is the other half of the decision, and we cover it — including the £7,500 grant — in our guide to how much a heat pump costs. The sensible conclusion is not that heat pumps are always cheaper, but that design quality decides whether yours will be.

Frequently Asked Questions

At what efficiency does a heat pump break even with gas?

At the October to December 2026 capped rates of 26.32p per kWh for electricity and 7.97p per kWh for gas, a heat pump needs a SCOP of about 3.0 to match a gas boiler running at 90% efficiency. Above that, it is cheaper per unit of heat; below it, it costs more.

Why is electricity so much more expensive than gas?

Electricity carries more of the costs of running and upgrading the energy networks and funding government schemes, and gas has historically been priced lower per unit. That price gap — sometimes called the spark gap — is the main reason heat pump running costs are so sensitive to efficiency.

Will a heat pump save me money if my boiler is old?

More likely, yes. The comparison above uses a modern boiler at 90% efficiency. An old boiler working at 70–80% efficiency costs roughly 10p to 11.4p per kWh of heat at current gas prices, which a heat pump at SCOP 3 beats comfortably.

Do heat pumps cost more to run in very cold weather?

Efficiency does fall as outside temperatures drop, because the pump works harder to extract heat. But SCOP is a seasonal average, so cold snaps are already accounted for in the figures used here. A correctly sized system will still heat your home in a UK winter.