Boiler vs Heat Pump Cost Calculator
Instantly compare the annual running costs of a gas boiler versus an air source heat pump. Estimate your potential savings and installation payback period.
Compare Your Heating Costs
Enter your home’s heating demand, current energy prices, and system efficiencies. The calculator instantly projects annual running costs and the payback period for upgrading.
Heating Cost Estimator
See how a gas boiler compares to a heat pump for your home.
Understanding the Metrics
Key factors that influence your heating bills
Coefficient of Performance (COP)
A heat pump’s COP measures its efficiency. A COP of 3.5 means it produces 3.5 kWh of heat for every 1 kWh of electricity it consumes, making it 350% efficient.
The Price Ratio
Because electricity is typically 3 to 4 times more expensive per kWh than gas, a heat pump needs a COP that is proportionally higher than the boiler’s efficiency to be cheaper to run.
Annual Heating Demand
This is the total heat energy your home requires in a year. Well-insulated, modern homes may only need 6,000–8,000 kWh, while older homes may need 15,000+ kWh.
Payback Period
This is the time it takes for the annual running cost savings to cover the extra upfront cost of installing a heat pump instead of a boiler. Government grants can significantly shorten this.
Gas Boiler vs Air Source Heat Pump
Generalised comparisons to help you understand the broader differences beyond just the running costs.
| Feature | Gas Boiler | Air Source Heat Pump |
|---|---|---|
| Efficiency | 85% – 90% | 300% – 400% (COP 3.0 – 4.0) |
| Carbon Emissions | High (burns fossil fuels) | Low (especially with green electricity tariffs) |
| Upfront Cost | Lower (£2,500 – £4,000) | Higher (£8,000 – £15,000) |
| Maintenance | Annual service recommended | Annual check recommended, similar to AC |
| Lifespan | 10 – 15 years | 15 – 20+ years |
| Flow Temperature | High (60°C – 80°C) | Low (35°C – 55°C, requires larger radiators/UFH) |
Heating Cost Calculator FAQ
Answers to the most frequently asked questions about comparing gas boilers and heat pumps.
The heat pump running cost is calculated by dividing your annual heating demand (in kWh) by the heat pump’s Coefficient of Performance (COP) to find the electricity required. This is then multiplied by your electricity price per kWh.
COP stands for Coefficient of Performance. It measures the efficiency of a heat pump. A COP of 3.5 means that for every 1 kWh of electricity consumed, the heat pump produces 3.5 kWh of heat energy by extracting ambient heat from the outside air.
It depends on the ratio of electricity prices to gas prices, and the efficiency of the systems. Because electricity is typically more expensive per kWh than gas, a heat pump needs a COP high enough (usually above 3.0) to offset the higher unit cost of electricity compared to a boiler’s efficiency.
A typical payback period for an air source heat pump, when replacing an old gas boiler, ranges from 7 to 15 years, depending on installation costs, available government grants (like the Boiler Upgrade Scheme in the UK), and the relative prices of gas and electricity.
This calculator focuses specifically on the space heating running costs to provide a direct apples-to-apples comparison of the heating technology. Standing charges apply to both, and hot water demand can be added to the “Annual Heating Demand” field if you wish to estimate total energy use.