1. What heats your home today?
Pick whichever your main heating uses.
Add up last year's bills, or use the typical figure for your home below.
3. What size is your home?
We use this to estimate the size of heat pump you'd need.
4. Do you have solar panels?
Free electricity from your roof cuts what the heat pump costs to run.
5. Your options
Both are on to start with. Leave them on unless you know they don't apply.
Your estimated saving
£407a year
Over 15 years that's around £6,105 off your heating bills.
Now: Gas boiler
£950 / year
With heat pump
£543 / year
You save
£407 / year
What about the upfront cost?
- Heat pump install (DESNZ median for this size)
- £12,200
- Less government grant
- -£7,500
- You pay
- £4,700
- A new gas boiler would cost
- ~£2,750
If your boiler needs replacing anyway, the heat pump costs about £1,950 more upfront (before any radiator upgrades), earned back in roughly 4.8 years from running cost savings. That assumes you have the gas supply disconnected, so you stop paying its standing charge (about £108 a year). Keep gas for cooking and it takes longer. It leaves out a heat pump's dearer servicing.
Like the look of £407 a year?
These are estimates. The only way to know your real saving is a free quote from an MCS-certified installer. Takes about 60 seconds, no obligation.
How we worked this out
Energy prices: Ofgem price cap for 1 October to 31 December 2026 (Direct Debit, GB average): gas 7.97p/kWh, electricity 26.32p/kWh. There is no VAT on domestic electricity from 1 October 2026 to 31 March 2027; the gas figure includes 5% VAT. Heat pump tariff blended at 20p/kWh (an estimate for Cosy Octopus, E.ON Next Pumped or EDF Heat Pump Tracker on a heat pump load profile, not a quoted rate). Heating oil 11.31p/kWh (111.52p/litre plus 5% VAT, over 10.35 kWh/litre; BoilerJuice UK average, 23 October 2026). LPG at the price you enter (we start from 75p a litre, our estimate: there's no published average).
Heat pump efficiency: a seasonal efficiency of 3.5. That sits between two measured figures: a median of 2.80 across 291 air source heat pumps in the government's Electrification of Heat trial (installed in 2020 and 2021, whole system), and an average of 4.01 across the 307 systems on heatpumpmonitor.org with a full year of data when we checked in October 2026, a self-selected group of air and ground source systems, mostly high temperature capable R290 units. The break-even with a 90% gas boiler on a standard tariff is a SCOP of about 2.97.
Typical bill ranges: for a 3-bed using 9,500 to 10,300 kWh of heat a year (DESNZ's median and mean gas use for 3 bedrooms in England and Wales, through a 90% boiler): gas £950 to £1,000 (with the standing charge, which the saving assumes you stop paying by having the gas supply disconnected), oil £1,250 to £1,350, LPG £1,200 to £1,300 on our LPG price, direct electric heating £2,500 to £2,700. At these prices a unit of heat from oil costs about 1.5 times as much as from gas, and from LPG about 1.4 times, which is why the saving from switching is bigger.
Solar: A 4kW system in central England generates around 3,800 kWh a year on our estimate (950kWh per kW). On the government's SAP 10.2 self-use formula, a typical 3-bed's heat pump uses about 350 kWh of that a year without a battery, and about 510 kWh with one (8 kWh usable). Most of its demand falls in winter, when panels make least, and the calculator works it out for your bill.
Install costs: DESNZ Boiler Upgrade Scheme statistics (August 2026), median cost of real installs by size: about £11,500 (4-6kW), £12,200 (6-8kW) and £13,900 (10-12kW). New gas boiler about £2,750 (our estimate). The £7,500 grant is the Boiler Upgrade Scheme (gov.uk) for England and Wales; £9,000 for oil or LPG heating with no mains gas connection until March 2027, which this calculator applies when you choose oil or LPG (if you also have a mains gas connection, take that extra off).
Estimates only. Your actual saving depends on the installer, flow temperatures, your home's heat loss and your electricity tariff. Always get a heat loss survey from an MCS installer for an accurate quote.
The Short Answer
A heat pump on a heat pump tariff saves about £407 a year at the calculator's defaults (a 3-bed gas home on a £950 heating bill). On the 26.32p price cap rate it's about £235, so we'd arrange the tariff when you switch.
With the £7,500 Boiler Upgrade Scheme grant it costs about £4,700. That's £1,950 more than the £2,750 you'd spend on a new boiler (our estimate), and it pays back that extra in about 5 years, assuming you have the gas supply disconnected (so its standing charge goes too) and before a heat pump's dearer servicing. Keep gas for cooking and count servicing, and it's about 8 years.
Put in your own bill and fuel above. Oil, LPG and electric heating save more.
By Heating Fuel
| Heating now | Typical 3-bed bill | Saving a year | Cost after grant | Payback on the extra over a boiler |
|---|---|---|---|---|
| Gas | £950 | £407 | £4,700 | about 5 years |
| Oil | £1,250 | £713 | £3,200 | n/a |
| LPG | £1,200 | £655 | £3,200 | n/a |
| Electric heaters | £2,500 | £1,957 | £4,700 | n/a |
All on a heat pump tariff, at the calculator's defaults. The oil and LPG rows include the extra £1,500 grant for homes with no mains gas connection, until March 2027. The payback column compares with a new gas boiler, so it only applies to the gas row. The electric row's cost is a typical install, which assumes radiators: a home with panel or plug-in heaters would also need radiators, pipework and a hot water cylinder, so it would pay more. Our air-to-air heat pump guide covers the option that avoids that.
How It Works
- Prices: the Ofgem price cap for 1 October to 31 December 2026: gas 7.97p and electricity 26.32p a kWh.
- Efficiency: a seasonal performance (SCOP) of 3.5. The 307 systems on heatpumpmonitor.org with a year of data averaged 4.01 when we checked, but the government's Electrification of Heat trial median was 2.80; ours sits between the two. The scheme's regulations set a minimum SCOP of 2.8.
- Grant: the Boiler Upgrade Scheme, for property owners in England and Wales replacing fossil fuel heating, which gov.uk defines as oil, gas, electric or LPG.
- Install costs: DESNZ's median for real installs by size.
Why the Tariff Matters
The heat pump tariff is modelled as a 20p blend (our estimate). On the 26.32p cap rate the saving shrinks, so in our view a heat pump tariff is worth arranging when you switch. Our heat pump tariff guide compares the real ones.