Show the formula and working
This free heat pump vs gas boiler cost calculator compares what a year of heating and hot water costs with your gas boiler and with an air source heat pump, for homeowners in the UK, Ireland and Europe. It starts from the gas you already use, converts it into the heat your home needs, and works out the electricity a heat pump would use, including the gas standing charge you stop paying if you cap the supply. It also shows the break-even efficiency and a simple payback.
Quick answer: A heat pump vs gas boiler cost calculator turns your gas use into heat, then divides by the heat pump’s SCOP. At the October 2026 cap, 9,500 kWh of gas in a 90% boiler costs £865.48 a year with standing charge. A heat pump with a SCOP of 3 costs £750.12, saving £115.36.
What Is a Heat Pump vs Gas Boiler Cost Calculator?
A heat pump vs gas boiler cost calculator is a tool that compares the yearly running cost of heating the same home with gas and with a heat pump. It uses your real gas use as the starting point, so the comparison reflects your house rather than an average.
The formula in plain words: multiply your yearly gas use by the boiler efficiency to get the heat your home actually receives. The gas cost is the gas kWh times the gas unit rate, plus 365 days of standing charge. For the heat pump, divide the heat by the SCOP (seasonal coefficient of performance) to get electricity kWh, then multiply by the electricity rate. If you keep gas for a hob, add the gas standing charge back on. The break-even SCOP is the heat multiplied by the electricity rate, divided by the gas costs you would stop paying.
How Do You Use the Heat Pump vs Gas Boiler Cost Calculator?
- Enter your Annual gas use for heating and hot water in kWh from your bills or supplier app.
- Set the Boiler efficiency of your current boiler and the Heat pump SCOP from your installer’s quote.
- Check the Gas unit rate, Gas standing charge and Electricity rate for the heat pump. If you will move to a heat pump tariff, enter its average rate.
- Tick Keep the gas supply (for example for a gas hob) if you will not cap the gas meter.
- Enter the Heat pump price after grant and, if your boiler needs replacing anyway, the New boiler price, if you would replace it anyway.
- Read the result and open “Show the formula and working” to see both yearly costs, the break-even SCOP and the payback.
Is a Heat Pump Cheaper to Run Than a Gas Boiler?
A heat pump is cheaper to run than a gas boiler when its SCOP is above about 3 at standard capped rates, or above about 2.6 if you also stop paying the gas standing charge. The reason is the price ratio: at the Ofgem price cap for October to December 2026, electricity is 26.32p per kWh and gas is 7.97p, so a kWh of electricity costs 3.3 times as much. A 90% efficient boiler brings that down to a break-even SCOP of 2.97. A cheaper heat pump tariff moves the balance strongly in the heat pump’s favour.
| Heat pump SCOP | Yearly cost at 26.32p | Saving vs gas at 26.32p | Yearly cost at 15p | Saving vs gas at 15p |
|---|---|---|---|---|
| 2.5 | £900.14 | £34.66 more | £513.00 | £352.48 |
| 3.0 | £750.12 | £115.36 | £427.50 | £437.98 |
| 3.5 | £642.96 | £222.52 | £366.43 | £499.05 |
| 4.0 | £562.59 | £302.89 | £320.63 | £544.86 |
The table compares a home using 9,500 kWh of gas a year in a 90% boiler, costing £865.48 with standing charge, against a heat pump with the gas supply capped. The 15p column is an example time of use rate, not a quoted tariff.
What SCOP Should I Expect From a Heat Pump?
A well designed air source heat pump typically reaches a SCOP of around 3, meaning about 3 kWh of heat for every kWh of electricity over a year. The Energy Saving Trust describes heat pumps as more than three times as efficient as a gas or oil boiler. The SCOP rises when radiators are large enough to run at a low flow temperature and falls when water must be heated to high temperatures. Your installer’s design should state the expected SCOP, and the heat pump size calculator helps check the output needed.
How Long Does a Heat Pump Take to Pay Back?
Payback ranges from about 10 years to never, depending almost entirely on your electricity rate and SCOP. With an example price of £4,500 after the £7,500 Boiler Upgrade Scheme grant, payback is 39 years at the standard cap rate with a SCOP of 3, but 10.3 years on a 15p tariff. If your boiler needs replacing anyway, subtract the cost of the new boiler from the heat pump price, which shortens the payback sharply. The grant applies in England and Wales and needs an MCS certified installer.
Should I Keep My Gas Supply After Fitting a Heat Pump?
Capping the gas supply saves the gas standing charge, which is £108.33 a year at the current cap of 29.68p a day. If you keep gas only for a hob, that standing charge stays, and in the default example the yearly saving shrinks from £115.36 to £7.03. Removing or capping a gas supply must be done by your gas network or a Gas Safe registered engineer. The gas bill calculator shows how much of your current bill is standing charge.
Worked Example: Comparing the Options
Example: a home uses 9,500 kWh of gas a year in a 90% efficient condensing boiler. The installer quotes a heat pump with a SCOP of 3.0 at £4,500 after the grant, and the homeowner would move to a heat pump tariff that averages 15p per kWh in this example. The gas meter will be capped.
- Heat needed: 9,500 kWh x 90% = 8,550 kWh.
- Gas boiler: 9,500 kWh x 7.97p + 365 x 29.68p = £757.15 + £108.33 = £865.48 a year.
- Heat pump: 8,550 / 3.0 = 2,850 kWh x 15p = £427.50 a year.
- Saving: £865.48 minus £427.50 = £437.98 a year, so payback is £4,500 / £437.98 = 10.3 years.
At the standard cap rate of 26.32p, the same heat pump would save only £115.36 a year. To see the electricity cost of the heat pump alone in more detail, use the heat pump running cost calculator.
Heat Pump vs Gas Boiler Cost Calculator FAQs
What is the break-even SCOP for a heat pump?
The break-even SCOP is the boiler efficiency multiplied by the electricity rate, divided by the gas rate. At 26.32p and 7.97p with a 90% boiler it is 2.97. If capping gas saves the standing charge as well, it falls to about 2.6 for a typical home.
Why use gas kWh instead of my heat demand?
Your gas bill is the most reliable record of how much heat your home uses. Multiplying gas kWh by boiler efficiency gives the heat delivered, which the heat pump must supply instead. It already includes hot water and your real habits and thermostat settings.
What boiler efficiency should I enter?
Use about 90% for a modern condensing boiler and 70 to 80% for an older non condensing one. Real efficiency is often lower than the rating when radiators run hot, because a condensing boiler only condenses with return water around 55 °C or below.
Does the calculator include hot water?
Yes, if your gas figure covers hot water, which it does for most combi and system boilers. Heat pumps heat water at a higher temperature than space heating, so their efficiency for hot water is lower. Use the overall SCOP from your quote that covers both.
Does a heat pump tariff make a big difference?
Yes. In the default example, moving from 26.32p to an average of 15p per kWh turns a £115.36 yearly saving into £437.98. The electricity rate is the single biggest factor in whether a heat pump costs less to run than gas.
Who can install a heat pump or remove a gas boiler?
Use an MCS certified installer for the heat pump, which is required for the Boiler Upgrade Scheme grant. Any work on the gas boiler, pipework or meter must be carried out by a Gas Safe registered engineer or your gas network, never as DIY.
Checked October 2026. Sources: Ofgem, Energy price cap unit rates and standing charges, Ofgem, Review of typical domestic consumption values: decision, Energy Saving Trust, Air source heat pumps, Ofgem, Boiler Upgrade Scheme, Wikipedia, Condensing boiler.