Heat Pump Running Cost Calculator

The question is almost never “how much does a heat pump cost to run” in isolation. It is whether it costs more or less than the gas boiler already in the house.

Enter your annual gas use and your two unit rates. The efficiency figures offered below are measured in real British homes rather than taken from a manufacturer's brochure, which is unusual and is the reason this page exists.

The comparison that actually matters

Strip everything else away and a heat pump beats a gas boiler when its efficiency advantage is larger than electricity's price disadvantage. That is one division.

A boiler running at 85% seasonal efficiency turns 100 kWh of gas into 85 kWh of heat. A heat pump at a COP of 3.5 turns 100 kWh of electricity into 350 kWh. So the pump can afford electricity to cost about 4.1 times what gas costs and still break even — 3.5 divided by 0.85.

At standard capped rates the actual ratio sits close to four, which is why the two technologies land so near each other in Britain and why small differences in your own system decide the outcome. That ratio is a policy artefact — environmental and social levies fall mostly on electricity — rather than anything about the machines. The same heat pump is comfortably cheaper to run in countries where the ratio is two.

Where the COP figures come from

They come from households running monitoring on their own systems and publishing the results, collected through the HeatpumpMonitor community and surfaced on our heat pump performance page.

That is real measurement over real winters in real British houses, which no manufacturer figure is. It cuts both ways, and the second half matters: the sample is self-selected. People who instrument their heat pump and publish the data tend to have well-commissioned systems and to have tuned them. Read these as what a good installation achieves, not as what an average one does.

Why there is no single COP on this page

You will notice you have to choose a metering arrangement, and that no figure spans them. That is deliberate.

A metering boundary records how much of the system the meters actually enclosed — whether they captured every watt the system drew including pumps and immersion heaters, or only part of it. A COP measured across the whole system is a different quantity from one measured across part of it, and the second reads higher simply because some of the electricity was never counted.

The gap between boundaries is wider than most of the differences anyone would want to draw from this data. Average across them and you produce a number that mainly measures how the meters were fitted. So this page does what the data page does: groups by boundary, and refuses to publish one figure across them.

The gas standing charge trap

A household that removes gas entirely stops paying the gas standing charge, which is worth roughly £117 a year. That is a real saving and heat pump comparisons frequently include it.

It only applies if the gas actually goes. Keep a gas hob or a gas fire and the standing charge stays with it, and a comparison that credited the saving anyway has quietly handed the heat pump the largest single advantage available in the whole calculation. That is why it is a tick box here rather than an automatic credit.

What this does not tell you

This is running cost only. Installation, grants, radiator upgrades and cylinder work are separate, vary enormously by property, and belong to a payback calculation rather than this one. For what the grants currently look like, the consumer scheme register records what each scheme is and where to apply.

Both annual figures hold your current unit rates constant for twelve months. That is this site's assumption for the purpose of the estimate, made on 7 August 2026, and not a published forecast. The electricity-to-gas ratio is the thing most likely to move, and it moves on policy decisions nobody publishes a forward series for. If the ratio changes, this answer changes with it — rerun it.

Your own gas use is also a better input than any estimate of it. If your bill gives cubic metres rather than kilowatt hours, the gas meter reading calculator converts them on the same formula your supplier uses. Full workings for every calculator here are on the methodology page.