At the Ofgem price cap for October to December 2026, heat from a gas boiler costs about 9.1p per kWh. A heat pump beats that once it averages a seasonal efficiency of about 2.9 or better: at 3.5 its heat costs about 7.5p per kWh. Below 2.9, it costs more. Design and installation decide which side a home lands on.

That is the honest version of the heat pump running costs vs gas question. It is not a promise of a saving, because the answer depends on the house and on how well the system is designed. Below are the sums behind it, using the same prices and the same method as our online estimate. Prices are the Ofgem cap from 1 October to 31 December 2026, checked on 19 October 2026.

Heat pump running costs vs gas: what are the prices this winter?

Ofgem's cap for 1 October to 31 December 2026, for a typical customer paying by direct debit, works out on average at:

  • Electricity: 26.32p per kWh, plus a standing charge of 54.83p a day.
  • Gas: 7.97p per kWh, plus a standing charge of 29.68p a day.

One thing is unusual about this winter. The government has removed VAT from electricity bills from 1 October 2026 to 31 March 2027, so the electricity figure carries no VAT. Gas still has 5% VAT on it. Both are averages: the standing charges in particular differ from region to region, and your own tariff may not be a capped one.

The next cap, for January to March 2027, is due to be announced on 25 November 2026.

How do you compare a heat pump with a gas boiler fairly?

A unit of electricity costs more than three times a unit of gas, which is why a heat pump can look expensive on paper. The comparison that matters is not the price of the fuel but the price of the heat that ends up in your rooms.

A gas boiler turns a kWh of gas into a little less than a kWh of heat. Our estimate assumes 88% for a condensing gas boiler. That is towards the generous end for a boiler running radiators in a real house, and it is chosen on purpose: crediting the old boiler generously keeps the comparison from flattering the heat pump.

A heat pump goes the other way. It uses electricity to move heat from the outside air into the house, and it delivers more heat than the electricity it uses. The measure is the seasonal coefficient of performance, or SCOP: a heat pump with a SCOP of 3.5 delivers, across a heating season, 3.5 kWh of heat for every kWh of electricity.

What does a kWh of heat cost from each?

Divide the price of the fuel by its efficiency and you get the price of the heat. At this winter's cap:

  • Gas boiler at 88%: 7.97p ÷ 0.88 = about 9.1p per kWh of heat.
  • Heat pump at a SCOP of 2.8: 26.32p ÷ 2.8 = about 9.4p.
  • Heat pump at 3.2: about 8.2p.
  • Heat pump at 3.5: about 7.5p.
  • Heat pump at 4.0: about 6.6p.

The crossover sits at about 2.9. A heat pump averaging better than that makes heat more cheaply than the boiler at these prices; one averaging worse makes it more expensively. That single number, the seasonal efficiency the system actually achieves in your house, is what the whole running cost question turns on.

What efficiency does a heat pump really reach?

Heat pumps carry an energy label with its seasonal efficiency at two flow temperatures, the temperature of the water sent round the radiators. Across the heat pumps in Mark's current price list, the label figures run from a SCOP of 3.2 to 4.0 at 55°C, with a middle value of 3.5, and from 4.1 to 5.3 at 35°C, with a middle value of 4.8.

Two cautions. Those are test results, measured under the label's standard conditions, and a real house is messier. And they show how much the flow temperature matters: the same unit is far more efficient making 35°C water than 55°C water.

Real homes have been measured too. The government-funded Electrification of Heat project monitored heat pumps fitted in a broad spread of British homes, and in interim results published in March 2023, Energy Systems Catapult reported that the median air source system reached a seasonal performance factor of 2.80. That is a median, so half did better, and the spread between the best and worst systems was wide.

The gap between the label and the median is where design earns its keep. A heat pump sized to the house's real heat loss, with radiators big enough to run at a low flow temperature, sits at the efficient end. One sized by guesswork and pushed to run hot to make up for small radiators sits at the other. Mark's estimates are designed around a 45°C flow temperature, and nothing is finalised until the house has been scanned and its heat loss worked out room by room, the method the heat pumps page walks through.

What about the gas standing charge?

If the heat pump replaces your only gas appliance and you have the gas supply taken out, you stop paying the gas standing charge. At this winter's cap that is 29.68p a day, or about £108 over a year. The electricity standing charge stays, because you keep your electricity supply either way.

Our estimate shows the gas standing charge on its own line and does not fold it into the headline figure, because it is only real if the gas actually goes.

Do heat pump tariffs make it cheaper to run?

They can. Some suppliers sell electricity tariffs built for heat pumps, with cheaper hours you can heat the house and the hot water in. Octopus Energy's Cosy Octopus is one example: it has three cheap periods a day, from 4am to 7am, 1pm to 4pm and 10pm to midnight, which Octopus says are 51% cheaper than its day rate, and a peak from 4pm to 7pm at 50% above it. You need a smart meter the supplier can read.

A tariff like that only helps if the system is set up to use it, for example by heating the hot water cylinder in a cheap period. The rates vary by region and change over time, so we do not quote them here. Compare the current rates for your area against the capped price before deciding.

Why not just use the running costs on my EPC?

An Energy Performance Certificate does show heating and hot water costs, and it is tempting to set those against a heat pump quote. The trouble is that the certificate works them out at the fuel prices assumed when it was produced, and with standard assumptions about how a household uses its heating. Take the before figure from an old certificate and the after figure from today's prices, and the difference between them is partly just the change in energy prices, which is not a saving anyone will see.

So our estimate does it the other way round. It takes one figure for how much heat your home needs in a year, then prices that same amount of heat twice: once through the boiler you have now, and once through the heat pump, both at the same cap. One demand, two fuels, one set of prices. Your real bills will still depend on how warm you keep the house and how many people live in it, but the comparison between the two systems is a fair one.

What changes after March 2027?

Two things to watch. The cap moves every three months, and the VAT break on electricity is due to end on 31 March 2027. If 5% VAT went back on electricity and nothing else changed, the crossover would rise from about 2.9 to about 3.05.

What matters for a heat pump is less the level of the cap than the gap between the electricity and gas prices. When electricity rises faster than gas, a heat pump needs to work more efficiently to stay ahead; when gas rises faster, the reverse. A well-designed system gives more room either way.

What this means for a Doncaster home

Most homes here are replacing a gas boiler, so the gas comparison above is the one that applies. Across the border it is the same story: on our Rotherham page, the 2021 Census has 82.8% of households there heating with mains gas alone.

The online estimate runs these sums for your home. It takes the heating demand from your home's energy certificate where there is one, applies the same cap prices to both the boiler and the heat pump, and shows the cost before and after. If the heat pump would cost more to run on today's prices, it says so rather than hiding it. To talk the figures through instead, call Mark on 07725 541383 on a weekday before 5pm.