Heat pump running cost calculator
Numbers checked against official sources on 7 October 2026
Find out whether a heat pump would cost more or less to run than your gas boiler. The calculator starts with Ofgem’s October–December 2026 price cap and a typical home. Change any number to match your own bill.
Estimates for heating and hot water only, using the figures you enter. They do not include the cost of buying the heat pump, servicing, or changes to the rest of your electricity bill. Everything is calculated in your browser; nothing is sent to us.
How the calculator works
It works out how much heat your boiler delivers, then how much electricity a heat pump would need to deliver the same heat:
Heat needed = gas kWh × boiler efficiency Heat pump kWh = heat needed ÷ SCOP Heat pump cost = heat pump kWh × electricity rate Gas cost = gas kWh × gas rate (+ 365 × standing charge if you close the account)
The break-even SCOP is the efficiency at which both cost the same. At the October 2026 price cap it is about 2.97 against a 90% boiler if you keep your gas supply, and about 2.6 if you close the account and save the standing charge. We explain the full workings, and what changes them, in heat pump vs gas boiler running costs.
Where to find your numbers
- Gas used per year: your annual statement, or the “annual consumption” figure on your bill or supplier app, in kWh. If your bill shows cubic metres or hundreds of cubic feet, use the kWh figure your supplier calculates from it.
- Unit rates and standing charges: on your bill or your tariff details. If you are on a standard variable tariff, they follow the price cap for your region.
- Boiler efficiency: new condensing boilers are about 90%. Older or badly set-up boilers do worse. If unsure, leave 90%: it is the cautious choice for a heat pump.
- SCOP: ask installers which seasonal efficiency their design is based on. It depends on your radiators, the flow temperature and how well the system is set up.
What the calculator does not include
- The purchase price. The typical installation is about £13,000 before the £7,500 grant: see heat pump costs in 2026 and the Boiler Upgrade Scheme.
- Gas you use for cooking, if any. If you keep a gas hob, untick the box: you will keep paying the standing charge.
- Time-of-use tariffs where the price changes by hour. Enter the average rate you expect the heat pump to pay.
- Servicing and maintenance for either system.
Frequently asked questions
What SCOP should I use?
If you have no quote yet, 3.0 is cautious and 3.5 is a reasonable figure for a well-designed air source system. Use the figure from your installer’s design once you have one.
Why does closing my gas account make such a difference?
The gas standing charge is a fixed daily fee, about £108 a year at the October 2026 average rate. If a heat pump replaces all your gas use, you stop paying it.
Does this work for oil or LPG heating?
Not directly, because the prices are per litre rather than per kWh. We are building a separate calculator for oil and LPG homes.
Is my data stored?
No. The calculation runs in your browser. Nothing you type is sent to us or anyone else.
