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 the annual gas use the heat pump would replace and your two unit rates. The efficiency figures offered below, when the monitoring read is available, are measured in British homes rather than taken from a manufacturer's brochure.

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.

Using the calculator’s editable starting examples, a boiler at 85% turns 100 kWh of gas into 85 kWh of useful heat, while a heat pump at COP 3.5 delivers 350 kWh from 100 kWh of electricity. On those assumptions, break-even is about 4.1 times. Neither efficiency is inferred for your equipment.

At standard capped rates the actual ratio is about 3.6 to one (1 July 2026 to 30 September 2026). Set that against the break-even ratio your own COP and boiler efficiency produce — the calculator prints the two side by side. The result changes with the rates and efficiencies entered; this read does not attribute the price ratio to any one policy or charge.

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. The read does not establish how those systems were commissioned or how they compare with an average British installation.

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.

Average across them and the result depends on 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 £106 a year — 29.04p a day, Ofgem’s cap rate for GB average, Direct Debit, 1 July 2026 to 30 September 2026. 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 overstates the avoided gas cost. 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, and not a published forecast. The separate Green Book paths shown by the calculator are appraisal assumptions rather than forecasts. If your rates or system inputs change, rerun the comparison.

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.