Home Heat Pump Guide

Heat Pump Cost Calculator UK: Estimate Your Costs

Working out what a heat pump will actually cost you — from installation through to annual running costs — is the single most important step before committing to this significant home upgrade. The trouble is that every property is different, and generic cost figures found online rarely reflect what you will actually pay.

That is why we built our free heat pump cost calculator. It takes your specific property details and gives you a personalised estimate of installation costs, annual running costs, and how those costs compare to your current heating system. This guide explains exactly how the calculator works, what inputs matter most, and walks through example calculations so you can see the logic behind the numbers.

Why Use a Heat Pump Cost Calculator?

You will find plenty of articles quoting average heat pump costs — typically somewhere between £10,000 and £18,000 installed. But averages are misleading. A well-insulated two-bedroom bungalow in Hampshire and a poorly insulated four-bedroom Victorian terrace in Yorkshire will have vastly different costs. The bungalow might need a 5kW unit costing £8,000 installed. The terrace might need a 12kW unit with radiator upgrades, pushing the total past £16,000.

A calculator that takes your specific inputs narrows the range dramatically. Instead of "somewhere between £10,000 and £18,000," you get "approximately £11,500 to £13,000" — a range you can actually plan around.

Our calculator also estimates running costs and compares them to your current heating bills, which is often the more important number. Installation cost is a one-off expense. Running costs continue for 20 years.

How Our Calculator Works

The Home Heat Pump Guide calculator uses a straightforward methodology based on established building physics and current market data. Here is what happens behind the scenes when you enter your details.

Step 1: Estimating Your Heat Demand

The calculator first estimates how much heat your property needs each year, measured in kilowatt-hours (kWh). This is your annual heat demand, and it is the foundation of every other calculation.

We estimate heat demand based on:

  • Property size — larger properties need more heat
  • Property type — detached homes lose more heat than mid-terrace or flats because they have more exposed walls
  • Insulation level — a well-insulated home might need 80 kWh per square metre per year; a poorly insulated one might need 180 kWh or more
  • Location in the UK — homes in Scotland and northern England need more heating than those in the south due to colder average temperatures

This estimate is not a substitute for a proper heat loss survey carried out by an MCS-certified installer, but it gives a reliable ballpark figure for planning purposes. For more detail on how we arrive at these numbers, see our methodology page.

Step 2: Sizing the Heat Pump

Once we know your estimated heat demand, we can determine the appropriate heat pump size. This is measured in kilowatts (kW) of heat output and determines which unit you need and what it will cost.

The sizing calculation considers your peak heat demand — not just annual consumption, but the maximum heat output needed on the coldest days. A typical UK home needs between 4kW and 16kW of heat pump capacity, with most falling in the 6-12kW range.

Step 3: Estimating Installation Cost

With the heat pump size determined, the calculator estimates the total installation cost. This includes:

  • The heat pump unit itself — prices vary by brand and output, typically £4,000 to £9,000 for the unit alone
  • Hot water cylinder — heat pumps require a specific type of cylinder, costing £800 to £1,500
  • Installation labour — typically two to three days of work, costing £2,000 to £4,000
  • Pipework and fittings — connecting the unit to your heating system, £500 to £1,500
  • Electrical work — a dedicated circuit and potentially a consumer unit upgrade, £300 to £800
  • Concrete base or wall brackets — for the outdoor unit, £200 to £500

The calculator then subtracts the BUS (Boiler Upgrade Scheme) grant of £7,500 if you indicate you are eligible. This grant, available to most homeowners in England and Wales, dramatically reduces the upfront cost. Read our full guide to heat pump grants for eligibility details.

Step 4: Estimating Annual Running Costs

Running costs depend on three things: your annual heat demand, the heat pump's efficiency (COP), and the electricity price you pay.

The formula is simple:

Annual electricity cost = Annual heat demand (kWh) / Seasonal COP x Electricity price per kWh

We use a seasonal COP (known as SCOP or SPF) rather than the peak COP quoted in marketing materials. The seasonal figure accounts for the fact that efficiency varies throughout the year — it is higher in mild weather and lower in the coldest months. For air source heat pumps in the UK, a seasonal COP of 2.8 to 3.5 is realistic.

For electricity prices, we use the current Ofgem price cap rate as the default, which you can override if you are on a different tariff. Many heat pump owners benefit from time-of-use tariffs like Octopus Cosy or Intelligent Go, which offer cheaper electricity during off-peak hours.

Step 5: Comparing to Your Current System

Finally, the calculator compares your estimated heat pump running costs to your current heating system. This comparison depends on what fuel you currently use:

  • Gas: Currently around 6.76p per kWh (Ofgem cap rate). Gas boilers are typically 85-92% efficient.
  • Oil: Prices fluctuate but average around 6-8p per kWh equivalent. Oil boilers are typically 85-90% efficient.
  • LPG: Around 8-12p per kWh equivalent. Similar boiler efficiency to gas.
  • Electric heating: At 24.50p per kWh with 100% efficiency (COP of 1.0). Heat pumps achieve COP of 2.8-3.5, so they use 65-72% less electricity than direct electric heating.

For a detailed comparison of gas and heat pump costs specifically, see our heat pump vs gas boiler guide.

What Inputs Matter Most?

Not all inputs have equal impact on the result. Here is what matters most, in order of importance:

1. Insulation Level

This is by far the biggest variable. A well-insulated home might need a 6kW heat pump and cost £900 a year to heat. A poorly insulated home of the same size might need a 12kW unit and cost £1,600 a year. Insulation affects both the installation cost (larger unit, potentially new radiators) and every year of running costs for the life of the system.

If you are unsure about your insulation level, your EPC rating gives a reasonable guide. Band A-C properties are generally well insulated. Band D is average. Band E-G suggests significant insulation improvements would be beneficial — and might even be required before a heat pump installation under BUS grant conditions.

2. Property Size and Type

A larger property needs more heat, which means a larger heat pump and higher running costs. Property type also matters — a detached home has four exposed walls and typically more roof area, while a mid-terrace has only two exposed walls and shares heat with its neighbours.

3. Current Fuel Type

Your current fuel type does not affect the installation cost or running cost of the heat pump itself, but it completely changes the savings comparison. Switching from oil or LPG to a heat pump typically saves significantly more than switching from mains gas, because oil and LPG are more expensive per kWh of useful heat.

4. Electricity Tariff

Most people default to the standard Ofgem cap rate, but if you switch to a heat pump-friendly tariff, you could reduce running costs by 15-30%. This is worth factoring in, as it significantly improves the payback period.

Example Calculations

Here are three worked examples using our calculator to show how costs vary by property type.

Example 1: Three-Bedroom Semi-Detached, Well Insulated

  • Property size: 95 square metres
  • Insulation: Good (EPC C)
  • Location: Midlands
  • Current fuel: Mains gas
  • Estimated heat demand: 9,500 kWh per year
  • Heat pump size: 6kW
  • Installation cost: £11,000 (before grant)
  • After BUS grant: £3,500
  • Annual running cost: approximately £810 (SCOP 3.2, 24.50p/kWh)
  • Current gas cost: approximately £715 (90% efficient boiler, 6.76p/kWh)
  • Annual cost difference: Heat pump costs approximately £95 more per year on the standard tariff

This example shows the reality for many gas-heated homes — running costs are similar. The financial case rests on the grant reducing the upfront cost and the heat pump lasting 20+ years versus 12-15 for a gas boiler.

Example 2: Four-Bedroom Detached, Average Insulation

  • Property size: 150 square metres
  • Insulation: Average (EPC D)
  • Location: North East England
  • Current fuel: Oil
  • Estimated heat demand: 21,000 kWh per year
  • Heat pump size: 11kW
  • Installation cost: £14,500 (before grant)
  • After BUS grant: £7,000
  • Annual running cost: approximately £1,725 (SCOP 2.9, 24.50p/kWh)
  • Current oil cost: approximately £1,890 (87% efficient boiler, 7.5p/kWh)
  • Annual saving: approximately £165 per year

Oil-heated properties often see the strongest financial case for switching. The savings are immediate and compound over the system's lifetime. Our running costs guide explores this further.

Example 3: Two-Bedroom Bungalow, Well Insulated

  • Property size: 70 square metres
  • Insulation: Very good (EPC B)
  • Location: South East England
  • Current fuel: Mains gas
  • Estimated heat demand: 5,600 kWh per year
  • Heat pump size: 5kW
  • Installation cost: £9,500 (before grant)
  • After BUS grant: £2,000
  • Annual running cost: approximately £490 (SCOP 3.3, 24.50p/kWh)
  • Current gas cost: approximately £420 (92% efficient boiler, 6.76p/kWh)

For a small, well-insulated property on mains gas, the running costs are close. But with the BUS grant, the upfront cost after the grant is just £2,000 — meaning you get a brand-new, low-carbon heating system for less than the cost of a replacement gas boiler.

What the Calculator Cannot Tell You

No online calculator can replace a proper survey by an MCS-certified installer. Our calculator gives you a reliable estimate for planning purposes, but the final cost will depend on factors that can only be assessed on site:

  • The exact condition and size of your existing radiators
  • Whether your electrical supply needs upgrading
  • Pipework routes and any structural complications
  • Access for the outdoor unit and any planning constraints
  • The specific heat pump brand and model recommended for your property

We always recommend getting at least three quotes from MCS-certified installers. You can start that process through our free quotes service, which connects you with vetted installers in your area.

Frequently Asked Questions

How accurate is the heat pump cost calculator?

Our calculator typically estimates within 10-15% of the final installed cost for straightforward installations. Complex properties — listed buildings, homes needing significant radiator upgrades, or properties with difficult access — may see greater variation. The running cost estimate is usually closer to actual figures because it depends on fewer site-specific variables.

Does the calculator include the BUS grant?

Yes. If you indicate you are eligible for the Boiler Upgrade Scheme grant (currently £7,500 for air source heat pumps), the calculator subtracts this from the estimated installation cost. See our grants guide for eligibility details.

What electricity price does the calculator use?

The default is the current Ofgem price cap rate for electricity (24.50p per kWh as of early 2026). You can override this if you are on a different tariff. If you are considering a time-of-use tariff, entering your expected average rate will give a more accurate running cost estimate.

Can I use the calculator for ground source heat pumps?

Yes. The calculator allows you to select either air source or ground source. Ground source heat pumps have higher installation costs but also higher seasonal efficiency, so the running costs are typically lower. Read our ground source heat pump guide for more detail.

Why does my estimate differ from quotes I have received?

Quotes from installers include a site-specific assessment and may include items the calculator cannot predict — such as extensive radiator upgrades, scaffolding, or electrical supply upgrades. If your quotes are significantly higher than the calculator estimate, ask the installer to break down the costs so you can see where the additional expense lies.

Should I improve insulation before installing a heat pump?

In many cases, yes. Improving insulation reduces the required heat pump size (and therefore cost), reduces running costs every year, and improves comfort. Our suitability checker can help you assess whether insulation upgrades would be beneficial before installation.