Heat pump vs boiler: which costs less to run?

The two numbers that decide everything

Running cost comes down to two things: the price of your fuel, and how efficiently your system turns it into heat. At the October 2026 price cap, electricity is 26.32p/kWh and gas is 7.97p/kWh (checked October 2026).

A modern gas boiler is around 90% efficient: each kWh of gas becomes 0.9kWh of heat, so a unit of heat costs 7.97 ÷ 0.9 ≈ 8.9p. A heat pump doesn't burn fuel — it moves heat — and a well-designed one delivers about 3 units of heat per unit of electricity (a seasonal efficiency, or SCOP, of 3.0). So its unit of heat costs 26.32 ÷ 3.0 ≈ 8.8p.

Read that again: at current prices, a good heat pump and a good gas boiler cost almost exactly the same to run. Anyone telling you heat pumps are dramatically cheaper — or ruinously expensive — to run than gas is selling something.

When the heat pump wins

Against oil and LPG. Heating oil and LPG cost far more per unit than mains gas, so a heat pump beats them comfortably on running costs alone — often by 30–50% (estimate). Off-mains homes are the heat pump's happiest customers.

With a high SCOP. The 3.0 figure is a decent expectation, not a ceiling. Well-designed systems with underfloor heating hit 3.5–4.0, at which point each unit of heat costs 6.6–7.5p — clearly cheaper than gas. Design quality is the whole game.

With solar panels. A heat pump running partly on home-grown solar electricity sidesteps the 26.32p import price for those hours. Solar + heat pump is the combination that genuinely moves the needle.

On carbon, always. Even where running costs tie, the heat pump's carbon footprint is far lower — and falls every year as the grid greens. If that matters to you, it is a real part of the value.

When the boiler wins

Cheap gas, poor heat pump design. Flip the SCOP the other way: a badly designed system limping along at SCOP 2.2 makes heat at 12p a unit — a third more expensive than gas. Bad installs exist, and they are the source of most heat-pump horror stories.

Upfront cost. This comparison is running costs only. A new boiler is £2,000–£3,500 installed (estimate); a heat pump is £7,000–£13,000 before the £7,500 Boiler Upgrade Scheme grant. The grant closes most of the gap, but not all of it — and it doesn't cover the hassle factor of a bigger install.

Hot water habits. Heat pumps heat water more slowly and to lower temperatures. Big bath-loving households sometimes find the cylinder recovery time annoying compared with a combi's endless hot water.

Maintenance: the quiet heat pump advantage

Boilers need annual servicing (£80–£120 a year is typical) and, by law, a gas safety check if you let the property. Heat pumps have no combustion, no flue gases and nothing to explode: an annual check-over is sensible but servicing bills are lower, and breakdowns are rarer — there are simply fewer moving parts to fail. Over 15 years, expect to spend meaningfully less keeping a heat pump alive than a boiler (estimate).

The verdict for most homes

On running costs alone versus mains gas: a wash. The heat pump's case is built on the £7,500 grant erasing the upfront gap, lower maintenance, lower carbon, and the pairing with solar. Against oil or LPG, it wins outright. Run your own numbers in our heat pump vs boiler comparer — and price both options with the heat pump cost calculator and boiler cost calculator before deciding.

The time-of-use wildcard

There's one more lever that can swing this comparison: when you buy your electricity. Standard variable tariffs charge the same 26.32p all day (October 2026 cap), but time-of-use tariffs — including ones designed specifically for heat pumps — offer much cheaper overnight or off-peak rates.

A heat pump paired with cheap off-peak electricity and a well-insulated house (pre-heat during the cheap window, coast through the expensive one) can cut the effective cost per unit of heat substantially — in some setups, below gas. We can't give you a single figure because tariffs change constantly, so treat this as homework: when you get heat pump quotes, ask each installer which tariffs their customers actually use, and model the numbers in our comparison tool with your real tariff. The gap between the best and worst tariff choice can be bigger than the gap between the two technologies.

FAQs

Is a heat pump cheaper to run than a gas boiler?

About the same at October 2026 prices: ~8.8p per unit of heat for a SCOP-3.0 heat pump vs ~8.9p for a 90%-efficient gas boiler.

What is a good SCOP?

3.0 is a solid expectation; 3.5+ is excellent. Below 2.5, running costs climb steeply — design quality matters enormously.

Do heat pumps work in cold UK winters?

Yes. Efficiency dips in the cold, but the seasonal SCOP figure already averages that in. Modern units are designed for UK winters.

Is a heat pump cheaper than an oil boiler to run?

Usually yes, by a clear margin — oil and LPG are far pricier per unit than mains gas.

Do heat pumps need annual servicing?

An annual check is sensible, but there is no combustion and no legal gas safety certificate. Maintenance bills run lower than a boiler's.