Heat Pump Running Cost Calculator
Compare air source heat pump vs gas boiler annual running costs on the July 2026 Ofgem price cap
Last updated: June 2026
Heat Pump vs Gas Boiler Cost Calculator
Enter your annual heating demand and efficiency to compare yearly running costs. Defaults use the Ofgem price cap unit rates for 1 July–30 September 2026.
What this calculator does
This heat pump running cost calculator shows whether an air source heat pump or a gas boiler is cheaper to run in your home, based on the July 2026 Ofgem energy price cap. It is built for UK homeowners weighing up a switch from gas, and for anyone trying to cut through the conflicting claims about heat pump bills. Because electricity costs roughly three and a half times as much as gas per unit, a heat pump only wins on running cost if it is efficient enough — and this tool shows you the exact tipping point.
You enter your annual heat demand (the heat your home actually needs), your heat pump's seasonal efficiency (SCOP), and the unit rates you pay. The calculator returns the estimated annual cost of each system, the yearly difference, the effective cost per kWh of useful heat for each, and the crucial break-even SCOP — the efficiency at which a heat pump matches a gas boiler. It also models a time-of-use tariff, which is where heat pumps can become clearly cheaper than gas.
How it works
The maths behind the comparison is straightforward:
- Heat pump cost = (annual heat demand ÷ SCOP) × electricity unit rate. A SCOP of 3.0 means the pump delivers 3 kWh of heat for every 1 kWh of electricity, so it uses one third of your heat demand as electricity.
- Gas boiler cost = (annual heat demand ÷ boiler efficiency) × gas unit rate. At 90% efficiency a boiler burns about 11% more gas than the heat it delivers.
- Break-even SCOP = electricity rate × boiler efficiency ÷ gas rate. Hit this SCOP and the two systems cost the same to run.
On the July 2026 cap the break-even SCOP is about 3.2. Below that, gas is cheaper to run; above it, the heat pump pulls ahead. A heat-pump-friendly time-of-use tariff lowers your effective electricity rate, which drops the break-even SCOP and can make the heat pump comfortably cheaper.
Worked example
Take a typical semi-detached home needing 12,000 kWh of heat a year, a heat pump at SCOP 3.0, and the July 2026 cap rates (electricity 26.11p, gas 7.33p) with a 90% boiler:
- Heat pump electricity: 12,000 ÷ 3.0 = 4,000 kWh × 26.11p = £1,044.40/yr
- Gas burned: 12,000 ÷ 0.90 = 13,333 kWh × 7.33p = £977.33/yr
- Difference: the gas boiler is about £67 cheaper per year at standard cap rates
- Effective heat cost: 8.70p/kWh (heat pump) vs 8.14p/kWh (gas)
- Break-even SCOP: 26.11 × 0.90 ÷ 7.33 = 3.21
Now switch the heat pump to a 15p time-of-use rate: 4,000 kWh × 15p = £600/yr, which is roughly £377 cheaper than the gas boiler. This is why the tariff you run a heat pump on matters as much as the hardware.
Frequently asked questions
Is a heat pump cheaper to run than a gas boiler in 2026?
It depends on efficiency and tariff. On the standard July 2026 Ofgem cap (electricity 26.11p, gas 7.33p per kWh), a heat pump needs a SCOP of about 3.2 just to match gas. A typical SCOP of 3.0 leaves it slightly more expensive than gas on the cap. On a dedicated heat-pump time-of-use tariff (around 15p or lower) it becomes clearly cheaper.
What is SCOP and why does it matter so much?
SCOP (Seasonal Coefficient of Performance) is the average units of heat a pump delivers per unit of electricity across a year. A SCOP of 3.0 means 3 kWh of heat per 1 kWh of electricity. Because electricity costs roughly 3.5× more than gas per unit, the SCOP largely decides whether the running cost beats gas.
How do I find my annual heat demand?
Check your annual gas use in kWh on a recent bill or smart meter, then multiply by your boiler efficiency (around 90%) to get useful heat. A typical UK home needs roughly 8,000–18,000 kWh of heat per year depending on size and insulation.
Does this include installation and standing charges?
No. This compares fuel running costs only. Standing charges are broadly similar whether you heat with gas or electricity, and installation costs (and any grants such as the Boiler Upgrade Scheme) are separate. Use this tool to understand the day-to-day running difference.
Source: unit rates from the Ofgem energy price cap for 1 July–30 September 2026 (electricity 26.11p/kWh, gas 7.33p/kWh, Direct Debit average). SCOP and boiler efficiency assumptions follow standard Energy Saving Trust guidance.