Heating Cost Comparison Calculator
Compare the running cost of two heating systems using your own heat demand, efficiency figures and fuel prices, and see the payback on switching.
💼 Are you a real estate agent or broker? Send this calculator to your buyers on your own branded listing page — every enquiry comes straight to your WhatsApp. Create free agent page →Comparing heating systems means comparing three things at once: how much heat the building needs, how efficiently each system produces it, and what each fuel costs. Change any one and the answer changes, which is why blanket claims about one technology being cheaper are usually wrong somewhere.
Efficiency here is expressed as a factor. A condensing gas boiler is around 0.88; a heat pump has a seasonal coefficient of performance typically between 2.5 and 4, meaning it delivers several units of heat per unit of electricity.
The calculation
Fuel used = heat needed ÷ efficiency factor. Annual cost = fuel used × price per kWh. The payback on switching is the extra installation cost divided by the annual running saving.
Worked example
A house needing 15,000 kWh of heat. A gas boiler at 0.88 efficiency burns 17,045 kWh at 0.07, costing 1,193 a year. A heat pump with a seasonal factor of 3.2 uses 4,688 kWh of electricity at 0.28, costing 1,313. At these prices the heat pump costs 120 a year more to run, so the 8,000 installation premium never repays on running cost alone.
The price ratio is what decides it
A heat pump beats a gas boiler when the electricity-to-gas price ratio is below roughly the coefficient of performance divided by boiler efficiency — about 3.6 in the example above. At a ratio of 4.0, as used here, gas wins. This is why the same technology is clearly cheaper in one country and clearly not in another.
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Create your free property pageFrequently asked questions
What efficiency figure should I use for a heat pump?
The seasonal coefficient of performance for your climate and system, not the peak laboratory figure. Real-world seasonal figures are commonly 2.5 to 3.5 for air source, and lower in cold climates or with high-temperature radiators.
Why does the answer differ so much between countries?
Because it depends on the ratio between electricity and gas prices, which varies enormously. The same heat pump can be clearly cheaper to run in one country and clearly more expensive in another with identical equipment.
Should running cost be the only consideration?
No. Carbon emissions, air quality, maintenance costs, equipment lifespan, noise and any available grant all matter, and several of them may outweigh a modest running-cost difference in either direction.