Cost after the grant, and what it costs to run
No details needed. Change any figure to match your own quote or bills. Results are indicative — an MCS installer’s heat-loss survey and written quote are what count.
£5,326
Payable by you on this quote. The grant is deducted on the quote and invoice — you never receive it as cash.
Default quote = the official median installed cost for 2026 Q3 (DESNZ, published 29 October 2026), which includes the grant value. VAT on installing a heat pump in a home is 0% until 31 March 2027, then 5%.
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Difference per year at these prices.
Prices: Ofgem cap 1 October to 31 December 2026 — electricity 26.32p/kWh, gas 7.97p/kWh, gas standing charge 29.68p/day (GB average, Direct Debit); heating oil 114.8p/litre including 5% VAT (109.3p before VAT; BoilerJuice UK average for 1,000 litres, read 28 September 2026); 10.35 kWh per litre assumed. No VAT on household electricity from 1 October 2026 to 31 March 2027, which flatters heat pumps in this window. LPG prices vary too much to default — use your own bills. Illustrative, not a quote.
Where the defaults come from
Nothing in the calculator is a guess dressed as a number. The starting quote is the median installed cost of grant-funded jobs published by the Department for Energy Security and Net Zero: £12,826 for an air source heat pump and £34,630 for ground source in 2026 Q3, both including the grant value (29 October 2026 release). The grant bands are the ones GOV.UK lists: £7,500 for air source or ground source, and £9,000 where the home is heated by oil or LPG and has no mains gas connection, for applications up to 31 March 2027.
The running-cost panel uses the Ofgem price cap for 1 October to 31 December 2026: 26.32p per kWh for electricity and 7.97p for gas, the Great Britain average on Direct Debit. Electricity carries no VAT from 1 October 2026 to 31 March 2027. Heating oil is the BoilerJuice UK average read on 28 September 2026, put on the same VAT-inclusive basis at 114.8p a litre. The heat demand starts at 12,000 kWh a year, an illustrative three-bed home; change it to match your own bills.
Reading the result
The after-grant figure is what you pay the installer: the grant is deducted from the quote, and you never receive it yourself. If your balance comes out far above £5,326, the median for a mains-gas home, the quote is either for a larger or more complex job or it includes items worth questioning. If it comes out far below, ask what is left out, such as radiators or a cylinder.
The running-cost figure is a comparison, not a forecast. At the defaults a heat pump at a seasonal efficiency of 3 costs about £1,053 a year to heat the illustrative home, against about £1,063 for a gas boiler and £1,566 for oil. The single biggest lever is the efficiency the system achieves, which depends on design and flow temperature, followed by your tariff. The running costs comparison explains the sum in full, and the heat pump installation cost guide lists what each quote should contain.
Check a real quote
A calculator cannot see your house. Once you have a figure in mind, the next step is a survey and a written quote from an MCS-certified installer, ideally three to compare. If you want to ask us about a quote you already hold, or about which grant band applies, use the form below.
Ask about a heat pump quote
Tell us the home, what heats it now and where you are with quotes. Your enquiry comes to SEO-DONS LTD, the publisher of this guide, and we reply by email. We are not an installer, Ofgem or the government, and there is no charge.