Heat Pump vs Gas Boiler UK: Which Is Cheaper to Run?

If you are replacing a boiler or planning a new heating system, the heat pump vs gas boiler question in the UK comes down to one thing: which costs less to run under the Ofgem price cap? The answer depends on three numbers — the electricity-to-gas price ratio, your heat pump's seasonal efficiency (SCOP), and the flow temperature your radiators or underfloor heating requires. This article walks through the comparison without assuming one answer is right for everyone.

The UK has one of the highest electricity-to-gas price ratios in Europe. Under the Ofgem April 2026 price cap:

• Electricity: 24.5p/kWh
• Gas: 6.0p/kWh

That is a 4.08:1 ratio. For context, the US national average is roughly 3:1, and many European countries are below 3:1. This high ratio is driven by UK electricity pricing being tied to the marginal cost of gas-fired generation, plus policy costs (renewables subsidies, social levies) loaded onto electricity bills rather than gas bills. The consequence: a UK heat pump needs a seasonal coefficient of performance (SCOP) of roughly 4.0 to match the running cost of a 90% efficient gas boiler on fuel cost alone. This is achievable with well-designed systems using underfloor heating and flow temperatures of 35 °C, but harder with standard radiators requiring 50–55 °C.

A gas boiler converts fuel to heat at its efficiency rating. A modern condensing boiler at 90% efficiency turns 90% of the gas energy into heat in your home. At 6.0p/kWh, the effective cost per kWh of delivered heat is: 6.0p ÷ 0.90 = 6.67p per kWh of heat A heat pump moves heat rather than creating it. Its SCOP tells you how many kWh of heat it delivers per kWh of electricity consumed. At a SCOP of 3.0, the effective cost per kWh of delivered heat is: 24.5p ÷ 3.0 = 8.17p per kWh of heat → Gas wins on running cost At a SCOP of 4.0: 24.5p ÷ 4.0 = 6.13p per kWh of heat → Heat pump wins on running cost The crossover SCOP for the UK at current price cap rates is approximately 3.67 — above that, the heat pump has a lower per-kWh heat cost. Below that, gas is cheaper to run.

Annual heat demand of 11,000 kWh is typical for a UK 3-bed semi-detached home with moderate insulation. Standing charges excluded in the per-kWh comparison — see below. These are the running costs for fuel only. The full picture includes the standing charge advantage of removing the gas meter, the BUS grant for installation, and 0% VAT.

1. You Currently Heat with Oil or LPG

These fuels cost substantially more per kWh of heat than mains gas. At 82p/litre for heating oil (roughly 8.0p/kWh of fuel, or 9.4p/kWh of heat at 85% efficiency), even a SCOP 2.5 heat pump beats oil on running cost. For the 1.5 million UK homes off the gas grid, the comparison is not heat pump vs gas — it is heat pump vs oil or LPG — and the heat pump wins easily. Typical saving vs oil: £500–£800/year.

2. Your Heat Pump Achieves SCOP 4.0 or Higher

This requires low flow temperatures (35–40 °C), which typically means underfloor heating or oversized radiators, and a well-insulated home. New-build homes meeting Part L building regulations can often achieve this SCOP. At SCOP 4.0, the heat pump beats a 90% gas boiler on pure fuel cost, and the standing charge saving adds another £100–£130/year advantage.

3. You Have an Economy 7 or Time-of-Use Tariff

Some UK electricity tariffs offer overnight rates as low as 8–12p/kWh. A heat pump running predominantly during off-peak hours (with a buffer tank storing heat) can dramatically shift the running cost comparison. At 10p/kWh off-peak and a SCOP of 3.0, the effective heat cost is just 3.33p/kWh — roughly half the cost of gas.

1. Standard Radiators and Poor Insulation

If your home requires 55 °C+ flow temperatures, the heat pump's SCOP will be closer to 2.5–3.0 rather than 3.5–4.0. At SCOP 2.8, the heat cost is 8.75p/kWh vs 6.67p for gas — gas is about 24% cheaper to run. The UK's older housing stock (pre-1970s solid wall construction) is particularly challenging for heat pump efficiency. Before installing a heat pump in a poorly insulated home: improve the insulation, draught-proof, and consider upgrading to larger radiators or underfloor heating. These measures improve the performance of any heating system.

2. Your Boiler Is Relatively New

Replacing a 3-year-old condensing boiler with a heat pump rarely makes financial sense on running cost savings alone. Wait until the boiler approaches end of life (10–15 years for a modern condensing unit) before making the switch.

3. High-Efficiency Gas Boiler in a Mild Location

A 94% efficient gas boiler in a mild southern England location with low annual heat demand (7,000–9,000 kWh) has a small absolute running cost — perhaps £470–£600/year. The running cost saving from a heat pump (perhaps £50–£100/year) may not justify the installation cost, even with the BUS grant.

A unique advantage of switching entirely from gas to a heat pump in the UK is removing the gas standing charge. Under the Ofgem price cap, the daily gas standing charge is roughly 28–32p/day, or £102–£117/year. If you disconnect the gas supply entirely (not just stop using it), you eliminate this charge permanently. Combined with the avoided annual boiler service (£70–£100), the total non-fuel saving from eliminating gas is roughly £170–£220/year. This is a meaningful addition to the running cost comparison that is often overlooked.

The UK's electricity standing charge varies significantly by distribution region, which affects the total cost picture:

Removing gas saves the standing charge regardless of region. The higher-standing-charge regions (Scotland, South West) have a slightly larger absolute saving from eliminating gas.

• Carbon emissions: The UK grid's carbon intensity has dropped dramatically. A heat pump powered by today's grid produces roughly 40–60 g CO2 per kWh of heat — compared to roughly 200 g for burning gas on-site. As offshore wind and nuclear expand, the heat pump gets cleaner automatically.
• Cooling included: UK summers are getting hotter. A reversible heat pump provides cooling during heatwaves at no extra equipment cost.
• No annual boiler service: Gas boilers require annual safety checks. Heat pumps need less frequent servicing.
• Comfort profile: Heat pumps deliver steady, lower-temperature heat over longer periods — which some homeowners prefer to the hot-blast-and-off pattern of a gas boiler.

The comparison comes down to your specific numbers. Use our Heat Pump Cost & Savings Calculator (UK) to plug in your home type, current fuel, local standing charges, and the BUS grant. It shows annual running costs for both systems, the payback period, and whether the verdict favours a heat pump or a gas boiler at current Ofgem rates. No signup, no sales pitch — just the maths for your home.