A well-installed heat pump costs about the same to run as a gas boiler on a standard tariff, and noticeably less on a heat pump tariff. A badly installed one costs more. That’s the honest answer, and the difference between the two outcomes comes down to a single number that most homeowners have never heard of, so let’s walk through it properly, with real 2026 prices.
Why isn’t this a simple yes or no?
Because electricity costs more per unit than gas, but a heat pump does far more with each unit it uses.
As of mid-2026, under the energy price cap, a typical household on a standard tariff pays around 26p per kilowatt hour for electricity and around 7p per kilowatt hour for gas. Look at those figures alone and you’d conclude a heat pump has no chance, electricity is roughly three and a half times the price.
But a gas boiler and a heat pump use their fuel completely differently. A modern gas boiler burns gas to make heat, and even a good one loses some of that energy up the flue. In real homes, you typically get around 0.85 units of useful heat for every unit of gas you pay for.
A heat pump doesn’t burn anything. It uses electricity to move heat from the outside air into your home, which is why it can deliver three, sometimes four, units of heat for every one unit of electricity it consumes. That multiplier is called the SCOP — seasonal coefficient of performance, and it’s the number that decides everything.
What do the actual numbers look like?
Let’s do the sums per unit of heat delivered into your home, using those standard tariff prices.
With a gas boiler running at 85% efficiency, each unit of heat costs about 7p ÷ 0.85, roughly 8.5p.
With a heat pump achieving a SCOP of 3.5, each unit of heat costs about 26p ÷ 3.5, roughly 7.5p.
So a properly performing heat pump already edges out gas, even paying full price for every unit of electricity. Over a typical home’s annual heating demand, that difference is real but modest, perhaps £100 to £150 a year in the heat pump’s favour.
Now run the same sums with a poorly installed heat pump achieving a SCOP of only 2.5, and each unit of heat costs over 10p, comfortably more expensive than gas. This is why you’ll find people online swearing heat pumps are money pits and others swearing they’ve halved their bills. Both are telling the truth about their own installation.
How do heat pump tariffs change the picture?
This is where it gets genuinely interesting, and where most comparison articles are out of date.
Because a heat pump runs on electricity, you can put it on an electricity tariff designed for heat pump owners. Several major suppliers now offer these, with cheap overnight and off-peak rates that bring your average heating electricity cost well below the standard capped rate, in some cases closer to 15p per kilowatt hour averaged across the day.
Rerun the sum at 15p with a SCOP of 3.5 and each unit of heat costs around 4.3p, roughly half the cost of gas heating. For a typical home, that’s several hundred pounds a year saved, and it’s the setup we’d recommend to almost every heat pump customer.
There’s one more saving that rarely gets mentioned: if you remove gas from the house entirely, you stop paying the gas standing charge, currently around 29p a day, or a little over £100 a year, before you’ve used a single unit.
What’s a realistic SCOP, and how do you actually get one?
Independent monitoring of real UK installations, including the Energy Systems Catapult’s large field trials, shows well-designed systems routinely achieving a SCOP between 3 and 4. The best installations exceed that. The worst limp along below 2.5, and almost every one of those failures traces back to the same causes: no proper heat loss survey, an oversized or undersized unit, flow temperatures set too high, or radiators that were never checked against the new system.
None of that is luck. It’s design. A system specified from a room-by-room heat loss calculation, sized correctly, and set up to run at the lowest flow temperature your radiators allow will land in that 3-to-4 range, which, as the sums above show, is exactly where a heat pump becomes cheaper than gas.
What about the cost of the heat pump itself?
Fair question, because running costs are only half the story. A heat pump costs more to install than a like-for-like boiler swap, though the government’s Boiler Upgrade Scheme currently knocks £7,500 off an air source heat pump in England and Wales, which brings many installations surprisingly close to the cost of a premium boiler replacement.
Heat pumps also tend to last longer than gas boilers, twenty years or so against ten to fifteen, and have fewer parts that wear out, so over the life of the system the economics tilt further in the heat pump’s favour.
So which is cheaper for your home?
If your heat pump is designed properly and you pair it with a heat pump tariff: the heat pump, and not by a small margin.
If it’s designed properly but you stay on a standard tariff: roughly level with gas, usually slightly ahead, plus the saved gas standing charge if you disconnect entirely.
If it’s thrown in without a proper survey: gas would have been cheaper, and you’d be right to be annoyed.
Which is a long way of saying the installer matters more than the technology. Every heat pump we fit at OJ Gas & Heating starts with a full room-by-room heat loss survey, and we’ll show you the projected running costs for your actual house, not a national average, before you commit to anything. If you’d like those numbers for your home, get in touch and we’ll put them together.
Energy prices quoted are the Great Britain average under the Ofgem price cap for July to September 2026. The cap changes quarterly, but the underlying comparison, heat pump efficiency versus the electricity-to-gas price ratio, holds either way.
