Heat Pump Running Cost Calculator
Work out roughly what an air source heat pump will cost to run in a UK home, using your own numbers.
A medium UK home (12,000 kWh of annual heat demand) with a heat pump running at SCOP 3.0 costs about £1,044 a year in electricity, at the current Ofgem price cap of 26.11p/kWh (Jul-Sep 2026)1. A well-designed system at SCOP 3.5 or higher costs less, around £895 a year, which undercuts a typical gas boiler. Use the calculator below with your own home size, SCOP and tariff.
Your details
Typical annual heat demand: 12,000 kWh
SCOP measures how many units of heat you get per unit of electricity, averaged across a UK heating season. Higher is better.
Check a recent bill for your actual rate. 26.11p/kWh is the Ofgem Direct Debit price cap for 1 Jul-30 Sep 20261. Off-peak heat pump tariffs can be lower; see the tariff guide.
- Boiler Upgrade Scheme grant
- £7,500
- Electricity price cap
- 26.11p/kWh
- Gas price cap
- 7.33p/kWh
- Breakeven SCOP vs gas
- ~3.2
How the calculation works
This calculator estimates the electricity cost of running an air source heat pump for space heating and hot water in a UK home. It uses your home size to estimate annual heat demand, then divides by the SCOP (seasonal coefficient of performance) to find electricity consumption.
The formula: Electricity (kWh) = Heat demand (kWh) ÷ SCOP. Multiply that by your unit rate to get the annual cost. Real costs vary with insulation quality, thermostat settings and weather, so treat the result as a planning estimate rather than a bill guarantee.
Typical UK heat demand by home size
| Home size | Annual heat demand | Notes |
|---|---|---|
| Small (1-2 bed flat) | 8,000 kWh/year | Well-insulated modern flat |
| Medium (2-3 bed house) | 12,000 kWh/year | Semi-detached, average insulation |
| Large (4+ bed house) | 18,000 kWh/year | Detached, older build |
Frequently asked questions
Is this calculator accurate for my specific home?
It gives a reasonable estimate using typical UK assumptions, not a survey of your home. Actual cost depends on insulation, flow temperature, thermostat habits and weather. For a firm figure, get an MCS heat loss calculation from an installer.
What SCOP should I use if I do not know mine?
Use 3.0 as a realistic default for an existing UK installation. Well-designed low-flow-temperature systems reach 3.5 to 4.0; oversized or high-flow-temperature systems can fall to 2.5.
Does the calculator include installation cost or the grant?
No, it estimates running cost only. Installation typically costs £8,000 to £15,000 before the £7,500 Boiler Upgrade Scheme grant (England and Wales, as of Jul 2026)2.
Guides
- What is SCOP and why does it matter?
- Best electricity tariffs for heat pumps
- Heat pump vs gas boiler running costs
- How to size a heat pump correctly
- 5 factors that affect heat pump running costs
Sources
- Ofgem, Changes to the energy price cap between 1 July and 30 September 2026, accessed 3 Jul 2026.
- GOV.UK, Apply for the Boiler Upgrade Scheme: what you can get, accessed 3 Jul 2026.
- Energy Saving Trust, Air source heat pumps: costs, savings and benefits, accessed 3 Jul 2026.
Last reviewed: 3 July 2026. Rates follow the Ofgem quarterly price cap and will be updated at the next review.