How much would a heat pump cost to run compared with my gas boiler?
Compare the yearly running cost of your gas boiler and a heat pump from your own gas use, with official default prices and every formula shown on the page.
AI-generated image: Internet of Things News / OpenAI ChatGPT
After reading this article you will be able to:
- Estimate the yearly cost of the same heat from your gas boiler and from a heat pump, starting from last year's gas
- Find the break-even SCOP above which a heat pump costs less to run with your prices
- Redo the calculation by hand with the formulas and the worked example on this page
On this page
For a British home that burns 12,000 kWh of gas a year in an older boiler, a heat pump with a SCOP of 3 would cost about £690 a year to run against about £1,060 for the boiler, about £370 less if you close the gas contract (about £260 if you keep it for cooking), at the Ofgem price cap for October to December 2026. Your answer depends on your gas use, your boiler and the heat pump’s real efficiency. The calculator above opens on that example and works it out for your own figures, entirely in your browser: nothing you type is sent or stored. It also gives the break-even efficiency and, with a quote, the simple payback.
How to use it
- Gas used in the last 12 months. Add up the consumption on a year of bills. The calculator takes Smc, standard cubic meters, as on Italian bills, or kWh, as on British bills. If your bill counts gas in cubic meters, convert with the factor printed on it and enter kWh. To use your Italian bill’s own P instead of 10.70, multiply your Smc by P in kWh per Smc (P in GJ per Smc × 277.8) and enter kWh. Use the whole figure, heating and hot water.
- Your boiler. Choose “older, not condensing” or “condensing”; the efficiency field fills in by itself. If you know your boiler’s seasonal efficiency, type it.
- The heat pump’s SCOP, the number of units of heat it gives for each unit of electricity over a whole heating season. Take it from the installer’s quote or the maker’s technical data sheet (the EU label does not show it; the product information sheet gives seasonal efficiency in percent), at the water temperature your heating needs: about 35 °C for underfloor heating, 55 °C for most radiators. Is a heat pump worth it? explains more.
- Prices. The country menu fills in official average prices. For a closer answer, use the prices per kWh on your own bills.
- Gas standing charge. The fixed yearly part of the gas bill. Tick the box if you will keep the gas contract, for cooking or as a backup.
- Heat pump cost. Optional: the price on your written quote, minus any grant. If your boiler has to be replaced anyway, enter the difference between the heat pump quote and the boiler quote.
How the calculator works
The boiler turns only part of the gas into heat: that share is its seasonal efficiency. The heat pump must deliver the same heat, and it uses one kilowatt-hour of electricity for every SCOP kWh of heat. In symbols:
- Gas in kWh = Smc × 10.70 (Italian bills; enter kWh directly otherwise)
- Heat = gas kWh × boiler efficiency
- Heat pump electricity = heat ÷ SCOP
- Boiler cost per year = gas kWh × gas price + gas standing charge
- Heat pump cost per year = electricity kWh × electricity price, plus the gas standing charge only if you keep the gas contract
- Break-even SCOP = electricity price ÷ (gas price ÷ boiler efficiency), with standing charges left out. The part in brackets is what a kWh of heat costs from the boiler; above this SCOP the heat pump costs less to run.
- Simple payback in years = heat pump cost after grants ÷ yearly saving. It ignores price changes, interest and repairs.
SCOP is the seasonal version of the coefficient of performance. Under the result, a table gives the yearly saving (+) or extra cost (−) at SCOP 2.5, 3, 3.5 and 4, with electricity 20% cheaper, as entered and 20% dearer.
Rounding: money to the nearest 10 (euro or pounds), kWh to the nearest 100, the break-even SCOP to one decimal, payback to whole years; the sums use unrounded numbers. When the two costs are less than 10 apart, the result says they cost about the same to run, the table shows ≈ 0 and there is no payback.
Where the default values come from
| Value | Default | Source | Period | Checked |
|---|---|---|---|---|
| Electricity price per kWh | Italy €0.3142, Germany €0.3618, France €0.2485, Spain €0.2509 | Eurostat nrg_pc_204, households using 2,500 to 4,999 kWh a year, all taxes and VAT included | January to June 2026 | 31 October 2026 |
| Gas price per kWh | Italy €0.1137, Germany €0.1156, France €0.1347, Spain €0.0787 | Eurostat nrg_pc_202, households using 20 to 199 GJ a year, all taxes and VAT included | January to June 2026 | 31 October 2026 |
| Great Britain prices | electricity 26.32p, gas 7.97p per kWh; gas standing charge £108 a year | Ofgem price cap unit rates and standing charges, Direct Debit, average for England, Scotland and Wales; 5% VAT on gas, no VAT on electricity until 31 March 2027 | 1 October to 31 December 2026 | 31 October 2026 |
| Energy in 1 Smc of gas | 10.70 kWh | ARERA’s national conventional value of 0.03852 GJ per Smc, used in offers and contracts | current | 31 October 2026 |
| Boiler efficiency | older, not condensing 66%; condensing 84% | UK Government SAP 10.2, Table 4b, winter seasonal efficiency (codes 115 and 118; 102 and 104) | version of 11 April 2023 | 31 October 2026 |
| Heat pump SCOP | 3 | example value, change it to yours | n/a | n/a |
The bases differ. Eurostat’s notes on gas and electricity prices say they include network charges and meter rental, so the fixed parts of the bill are already spread over each kWh. That is why, as the note under the field says, the standing charge starts at 0 for Italy, Germany, France and Spain; if you keep the gas contract, enter the prices and standing charge from your own bills. Ofgem gives the British standing charge separately, 29.68p a day, £108.33 a year; the field shows £108. Italian bills use the local P printed on them, which can differ slightly from 10.70. The calculator shows source and check date under each price, efficiency and Smc field.
A worked example: an Italian home that burned 1,000 Smc
Choose Italy in the calculator: it fills in these values. Here they are redone by hand.
| Assumption | Value | Source |
|---|---|---|
| Gas used in a year | 1,000 Smc | example value |
| Energy in 1 Smc | 10.70 kWh | ARERA |
| Boiler | older, not condensing, 66% | SAP 10.2 |
| Heat pump SCOP | 3 | example value |
| Electricity price | €0.3142 per kWh | Eurostat, January to June 2026 |
| Gas price | €0.1137 per kWh | Eurostat, January to June 2026 |
| Gas standing charge | €0 (already in the price) | Eurostat |
- Gas: 1,000 × 10.70 = 10,700 kWh.
- Heat: 10,700 × 0.66 = 7,062 kWh, shown as 7,100.
- Heat pump electricity: 7,062 ÷ 3 = 2,354 kWh, shown as 2,400.
- Boiler cost: 10,700 × 0.1137 = €1,216.59, shown as €1,220.
- Heat pump cost: 2,354 × 0.3142 = €739.63, shown as €740.
- Difference: 1,216.59 − 739.63 = €476.96, shown as about €480 a year less with the heat pump.
- Break-even SCOP: 0.1137 ÷ 0.66 = €0.1723 per kWh of heat; 0.3142 ÷ 0.1723 = 1.82, shown as 1.8.
- Payback, with a quote of €10,000 after grants (example value): 10,000 ÷ 476.96 = 20.97, shown as 21 years.
Yearly saving with the heat pump, from the calculator’s own table:
| SCOP | Electricity 20% cheaper | As entered | 20% dearer |
|---|---|---|---|
| 2.5 | +€510 | +€330 | +€150 |
| 3 | +€620 | +€480 | +€330 |
| 3.5 | +€710 | +€580 | +€460 |
| 4 | +€770 | +€660 | +€550 |
With a condensing boiler at 84% instead, the same gas gives 8,988 kWh of heat, the heat pump needs about 3,000 kWh, and the saving at SCOP 3 falls to about €280 a year; the break-even rises to 2.3.
What the calculator does not include
- Maintenance and repairs of either machine.
- Prices that change. The defaults are averages for one period.
- Financing. Loan interest is left out of the payback.
- The electricity standing charge. You pay it either way. Extra kWh may mean a higher contracted power (in Italy “potenza impegnata”), which costs more, or a different price band.
- Hot water made separately. If an electric heater makes your hot water, it is not in the result. If the boiler makes it, the calculator assumes the same SCOP for it, though hotter tap water lowers a heat pump’s efficiency. Take gas used for cooking out of the total.
- The gap between the datasheet and your home. In the British Electrification of Heat trial, the efficiency measured in homes was lower than the SCOP worked out at design stage in 91.9% of them, and the median measured figure was 17.9% below the median design SCOP (project report, December 2024). Also read the table row one step below your quoted SCOP.
This page explains how it works and what to ask; it is not financial advice or a design. Electrical work and paperwork are for a qualified installer or advisor.
Where to go next
- Is a heat pump worth it compared with a gas boiler? gives the break-even SCOP by country.
- My gas boiler is old: new boiler, hybrid or heat pump? compares the three choices.
- How to read your electricity bill finds your price per kWh.
- Grants and tax breaks by country lists what lowers the price.
Common questions
Is a heat pump cheaper than gas to run?
It is when its SCOP is higher than the price of a kWh of electricity divided by the cost of a kWh of heat from your boiler. With the Italian average prices for the first half of 2026 and an older boiler at 66% efficiency, that break-even SCOP is about 1.8; with a condensing boiler at 84% it is about 2.3. The calculator works it out for your own prices.
How much does it cost to heat 100 square meters with a heat pump?
Floor area alone does not tell you: two homes of 100 square meters can need very different amounts of heat, depending on insulation, climate and how warm you keep them. The calculator starts from the gas you burned last year instead. For an Italian home that used 1,000 Smc with an older boiler, a heat pump with a SCOP of 3 would cost about 740 euro a year at the average price for the first half of 2026.
How much does a heat pump add to the electricity bill?
The extra electricity is the heat your home uses divided by the heat pump's SCOP. In the Italian example on this page, 7,100 kWh of heat at a SCOP of 3 means about 2,400 kWh more a year, about 740 euro at 0.3142 euro per kWh, while the gas bill of about 1,220 euro goes away if you close the gas contract.
Why is my bill so high with a heat pump?
The electricity bill rises because the heat pump replaces the gas you used to buy, so compare the two bills together. If the total is still higher than expected, the heat pump may work below the efficiency promised at design stage: in a large British trial, measured efficiency was lower than the design SCOP in about 92% of homes. Ask the installer to check the water temperature and settings against the design.
Topics: heat pumps, gas boiler, calculator, energy prices, SCOP