Costs & Savings

Heat pump vs gas boiler running costs in the UK — 2026 guide

Last updated: March 2026 · 6 min read

One of the most common questions homeowners ask before considering a heat pump is whether it will actually cost less to run than their current gas boiler. It is a reasonable concern — heat pumps are a significant investment, and running costs matter for the long-term case. The honest answer is that it depends on your property, your current energy tariff, and how well the system is designed and installed. This article sets out the key factors clearly.

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Quick answer

Whether a heat pump costs more or less to run than a gas boiler depends primarily on the efficiency of the installation and the relative price of electricity versus gas. In a well-insulated property with a correctly sized and installed heat pump, running costs can be comparable to or lower than a gas boiler. In a poorly insulated property or with an inefficient installation, costs can be higher. The gap between electricity and gas unit prices in the UK is the most significant variable.

Note: Energy prices change frequently. The figures used in this article reflect approximate 2026 tariff levels under the Energy Price Cap and are for illustrative purposes only. Always check current rates from your supplier before making calculations.

How heat pumps and gas boilers use energy differently

A gas boiler burns gas to generate heat — for every unit of energy in the gas, you get roughly one unit of heat out, minus losses. Modern condensing boilers operate at around 90% efficiency, meaning they convert about 90% of the gas they burn into useful heat.

A heat pump works differently. Rather than generating heat by burning fuel, it moves heat from the outside air into your home using a refrigerant cycle — similar in principle to how a fridge works, but in reverse. Because it is moving heat rather than creating it, a heat pump can deliver more energy in heat than it consumes in electricity. This ratio is called the Coefficient of Performance (COP). A well-installed air source heat pump in a suitable property typically achieves a COP of between 2.5 and 3.5, meaning it delivers two and a half to three and a half units of heat for every unit of electricity it uses.

The electricity vs gas price challenge

Here is where the running cost comparison gets complicated for UK homeowners. Electricity costs significantly more per unit than gas in the UK. Under the 2026 Energy Price Cap, electricity costs approximately 24p per kWh while gas costs approximately 6p per kWh — meaning electricity is around four times more expensive per unit.

For a heat pump to match a gas boiler on running costs, it needs to deliver roughly four units of heat for every unit of electricity it uses — a COP of around 4. Many well-installed heat pumps in suitable properties achieve this, particularly during milder weather. However, during cold snaps when the heat pump has to work harder, the COP drops, and running costs rise accordingly.

Illustrative running cost comparison

Scenario	Gas boiler (est.)	Heat pump (est.)	Difference
Well-insulated 3-bed semi, average usage	~£900/yr	~£800–950/yr	Broadly comparable
Well-insulated 4-bed detached, average usage	~£1,400/yr	~£1,200–1,500/yr	Broadly comparable
Poorly insulated property, high heat demand	~£1,800/yr	~£2,000–2,400/yr	Heat pump likely higher

These are illustrative estimates only. Actual costs depend on your specific property, tariff, usage patterns, and system design. They are intended to give a sense of scale rather than precise predictions.

Factors that most affect heat pump running costs

Property insulation

This is the single most important factor. A heat pump in a well-insulated property runs at higher efficiency and lower cost. A heat pump in a poorly insulated property has to work harder, runs at lower efficiency, and costs more. Improving insulation before or alongside a heat pump installation makes a significant difference to running costs.

System design and installation quality

A heat pump that is correctly sized for a property's heat demand, installed with appropriately sized radiators or underfloor heating, and set up with correct flow temperatures will run significantly more efficiently than one that is over or under-sized. Poor installation is one of the most common reasons homeowners report disappointing heat pump performance. Using an MCS-certified installer who carries out proper heat loss calculations is essential.

Your electricity tariff

Some energy suppliers offer heat pump tariffs with lower overnight or off-peak electricity rates. If your heat pump can be configured to run more during cheaper rate periods — particularly for heating water — this can reduce running costs meaningfully. It is worth asking your installer and energy supplier about tariff options when planning the installation.

Hot water heating

Heating domestic hot water accounts for a significant portion of a household's energy use. Heat pumps can heat water efficiently, but the setup matters. A well-designed system with a properly sized hot water cylinder and appropriate temperature settings will perform considerably better than one that is not optimised for your household's hot water demand.

The longer-term picture

The running cost comparison between heat pumps and gas boilers is expected to shift over time in favour of heat pumps. The UK government has signalled an intention to rebalance energy tariffs to reduce the electricity-to-gas price ratio, which would make heat pumps more cost-competitive. Carbon costs on gas are also likely to increase over time. These are policy-dependent projections rather than certainties, but they form part of the long-term case for heat pump adoption.

The upfront cost reduction from the Boiler Upgrade Scheme grant — up to £7,500 — also changes the financial calculation significantly compared to paying the full installation cost. For homeowners whose properties are suitable, the grant makes the overall investment considerably more attractive.

When a heat pump is likely to save money vs a gas boiler

The property is well insulated with cavity wall insulation, loft insulation, and double glazing
The heat pump is correctly sized and installed by an experienced MCS-certified installer
Radiators are adequately sized for lower flow temperatures, or underfloor heating is used
A heat pump electricity tariff with lower off-peak rates is available and used
The existing gas boiler is old and inefficient, so the comparison baseline is poor

When a heat pump may cost more to run than a gas boiler

The property has high heat loss due to poor insulation or solid walls
The system is undersized or incorrectly installed, leading to low efficiency
Radiators are too small, forcing the heat pump to run at higher flow temperatures
A standard electricity tariff is used with no off-peak discount
The property has very high hot water demand that the system is not optimised for

Next steps

If you are considering a heat pump, the best way to understand whether it makes financial sense for your specific property is to speak to an MCS-certified installer who will carry out a proper heat loss assessment and provide a realistic view of expected running costs. A good installer will give you an honest picture rather than an optimistic one.

Before that conversation, check whether your property may qualify for the Boiler Upgrade Scheme grant — reducing the upfront cost by up to £7,500 changes the financial case significantly.

Check if your home may qualify for the £7,500 heat pump grant using our free 2-minute eligibility checker. No obligation to continue.

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Summary

Heat pump running costs in the UK are broadly comparable to gas boiler costs in well-insulated properties with well-designed installations. The electricity-to-gas price ratio is the main challenge, but a heat pump's higher efficiency can offset this in the right circumstances. Poor insulation and poor installation quality are the most common reasons heat pumps disappoint on running costs. The long-term direction of energy pricing in the UK is expected to favour heat pumps over time.