Heat pump cost calculator – the factors that matter
If you are considering replacing your gas boiler with a heat pump, the upfront price tag often raises the first question: what will this actually cost? The answer depends on a handful of key variables that interact with each other, meaning no two installations cost the same.
Heat pump costs depend on size, efficiency and insulation. A typical 7 kW air source model costs £8,000 after the £7,500 BUS grant and £600 per year to run. Check your home's insulation first.
- Size, SCOP and insulation drive 80% of total cost over 15 years.
- Typical 7 kW air source heat pump costs £8,000 after the £7,500 BUS grant.
- Running costs average £600 per year for a well-insulated 3-bed home.
- Ground source heat pumps range from £24,000 to £49,000 before grant.
- Heat pump size needed depends on your home's heat loss calculation.
- Heat pump cost calculator – the factors that matter
- Heat pump installation costs typically range from £7,000 to £15,000 after the Boiler Upgrade Scheme grant
- The size of your heat pump is measured in kilowatts and directly affects the price
- A heat pump’s efficiency is expressed as the Seasonal Coefficient of Performance (SCOP)
- Running costs for a heat pump depend on electricity prices and the SCOP
- Quick numbers a table comparing heat pump vs. gas boiler costs
- The key factor that determines your heat pump’s performance is your property’s heat loss
- Eligibility for the Boiler Upgrade Scheme grant requires an MCS-certified installer and a valid EPC
The three factors that determine roughly 80% of the total cost of ownership over 15 years are the heat pump’s size (kW output), its efficiency (SCOP), and the insulation level of your property, according to Energy Saving Trust modelling (Energy Saving Trust, 2026). A typical well-insulated 3-bedroom home with a 7 kW air source heat pump (SCOP 3.5) costs around £8,000 after the Boiler Upgrade Scheme grant and about £600 per year to run.
Heat pump installation costs typically range from £7,000 to £15,000 after the Boiler Upgrade Scheme grant
The Boiler Upgrade Scheme (BUS) provides a flat-rate grant of £7,500 towards an air source heat pump installation as of 2026, reducing the upfront cost for most homeowners (GOV.UK, 2026). Before the grant, a typical air source heat pump installation costs between £14,000 and £22,000, depending on system size and property type (Energy Saving Trust, 2026).
Ground source heat pumps are significantly more expensive, with pre-grant costs ranging from £24,000 to £49,000, though the BUS grant for these is also £7,500 (Energy Saving Trust, 2026). The grant is applied as a discount by the installer, not as cashback to the homeowner; the installer claims the grant from Ofgem after installation.
The size of your heat pump is measured in kilowatts and directly affects the price
Heat pump output is measured in kW, with common domestic sizes ranging from 5 kW to 16 kW for air source units (MCS, 2026). A 5–8 kW unit (suitable for a well-insulated 3-bedroom home) typically costs £7,000–£10,000 installed before the grant; a 12–16 kW unit can cost £12,000–£18,000 (Energy Saving Trust, 2026).
The required size is determined by a heat loss calculation (not just floor area), which considers insulation, windows, and local climate (MCS installation standards, 2026). A larger heat pump costs more upfront and may be less efficient if oversized, so accurate sizing matters for both cost and performance.
A heat pump’s efficiency is expressed as the Seasonal Coefficient of Performance (SCOP)
SCOP measures the average efficiency over a heating season; a typical air source heat pump achieves a SCOP of 3.0–4.0, meaning it produces 3–4 kWh of heat for every 1 kWh of electricity (MCS SCOP database, 2026). Higher SCOP values (e.g., 4.0+) mean lower running costs, but the unit itself may cost 10–20% more upfront (Energy Saving Trust, 2026).
The SCOP is influenced by the heat pump model, the property’s heating system (e.g., underfloor heating vs. radiators), and the climate zone. For example, underfloor heating operates at lower water temperatures, which improves SCOP compared to standard radiators.
Running costs for a heat pump depend on electricity prices and the SCOP
At 2026 electricity rates (approx. 24–28p per kWh, Ofgem price cap), a heat pump with a SCOP of 3.5 costs roughly £500–£800 per year to heat a typical 3-bedroom home, compared to £900–£1,200 for a gas boiler (Ofgem, 2026; Energy Saving Trust, 2026). The actual cost varies with the property’s heat demand (kWh per year), which is calculated from the property’s size, insulation, and usage patterns.
Heat pumps are most cost-effective when paired with a smart electricity tariff that offers lower rates during off-peak hours (e.g., Economy 7 or Octopus Agile). Without such a tariff, running costs can be 10–20% higher, depending on usage patterns.
Quick numbers a table comparing heat pump vs. gas boiler costs
| Cost factor | Air source heat pump | Ground source heat pump | Gas boiler (reference) |
|---|---|---|---|
| Installation cost (after BUS grant) | £7,000–£15,000 | £16,500–£41,500 | £1,500–£4,000 |
| Annual running cost (typical 3-bed home) | £500–£800 | £400–£700 | £900–£1,200 |
| Lifespan | 15–20 years | 20–25 years | 10–15 years |
| Annual maintenance cost | £150–£300 | £200–£400 | £80–£150 |
Sources: Energy Saving Trust cost tables, 2026; MCS lifespan data, 2026; Gas Safe Register boiler cost data, 2026.
The key factor that determines your heat pump’s performance is your property’s heat loss
A heat loss calculation (required by MCS installers) measures how quickly your home loses heat through walls, windows, floors, and roof; a well-insulated property requires a smaller, cheaper heat pump (MCS technical standards, 2026). Properties with poor insulation (e.g., single glazing, no cavity wall insulation) may need a larger unit, increasing upfront costs and reducing efficiency.
The calculation is done on-site by an MCS-certified installer using industry-standard software; homeowners can request a preliminary estimate based on their Energy Performance Certificate (EPC) (DESNZ EPC data, 2026). Improving insulation before installation can reduce the required heat pump size by 20–30%, lowering both upfront and running costs.
Eligibility for the Boiler Upgrade Scheme grant requires an MCS-certified installer and a valid EPC
To claim the £7,500 BUS grant, the heat pump must be installed by an MCS-certified contractor, and the property must have a valid EPC with no outstanding recommendations for loft or cavity wall insulation (DESNZ Boiler Upgrade Scheme eligibility criteria, 2026). The grant is applied as a discount by the installer, not as cashback to the homeowner; the installer claims the grant from Ofgem after installation.
Homeowners must also ensure the installer is registered with TrustMark for additional consumer protection (TrustMark, 2026). If your EPC shows missing insulation, you may need to address that first to qualify for the grant.
The direct answer the three most important heat pump cost factors are size, efficiency, and property insulation
Size (kW output) determines the upfront cost; efficiency (SCOP) determines running costs; and property insulation determines both the required size and the real-world efficiency. A typical scenario: a well-insulated 3-bedroom home with a 7 kW air source heat pump (SCOP 3.5) costs about £8,000 after the grant and £600 annually to run.
These three factors account for roughly 80% of the variation in total cost of ownership over 15 years, according to EST modelling (Energy Saving Trust, 2026; MCS performance data, 2026; DESNZ heat pump deployment analysis, 2026).
For a more detailed breakdown tailored to your property, use the heat pump running cost calculator on this site, which incorporates your specific heat demand and local electricity tariff.
Frequently Asked Questions
The three biggest factors are the heat pump's size in kW, its SCOP efficiency, and your home's insulation level, according to Energy Saving Trust modelling. These determine roughly 80% of total ownership costs over 15 years.
A typical 7 kW air source heat pump costs around £8,000 after the £7,500 Boiler Upgrade Scheme grant, according to GOV.UK. Before the grant, installation ranges from £14,000 to £22,000 depending on size and property type.
The Boiler Upgrade Scheme provides a flat-rate grant of £7,500 for both air source and ground source heat pumps in 2026, as confirmed by GOV.UK. The installer claims the grant from Ofgem after installation, reducing your upfront cost directly.
Ground source heat pump installation costs range from £24,000 to £49,000 before the £7,500 BUS grant, according to Energy Saving Trust. After the grant, you pay between £16,500 and £41,500.
A well-insulated 3-bedroom semi typically needs a 5–8 kW air source heat pump, based on MCS standards. The exact size depends on a professional heat loss calculation considering insulation, windows and room sizes.
