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Gas vs Electric vs Oil Heating — UK Costs
Comparing UK heating fuel options — running costs per kWh, efficiency, carbon emissions, future-proofing and the transition away from fossil fuels.
Side-by-Side Comparison
| Property | Gas Boiler | Oil Boiler | Electric Boiler | Heat Pump |
|---|---|---|---|---|
| Fuel cost (p/kWh) | ~7p | ~7p | ~26p | ~26p (but COP 3+) |
| Effective heat cost | ~7.9p/kWh | ~7.8p/kWh | ~26p/kWh | ~7-9p/kWh |
| Boiler efficiency | 92-94% | 90-93% | 99-100% | 280-400% (COP) |
| Annual cost (3-bed) | £800-1,200 | £900-1,400 | £2,500-3,500 | £600-1,000 |
| CO2 per kWh heat | ~200g | ~270g | ~136g | ~40-50g |
| Boiler replacement | £2,000-3,500 | £3,000-5,000 | £1,500-3,000 | £8,000-14,000 |
| Fuel storage | None (mains supply) | Oil tank (1000-2500L) | None | None |
| Future-proofing | Phase-out by 2035 | Phase-out starting | Expensive to run | Government-backed future |
UK Running Cost Comparison (2026)
For a typical 3-bedroom semi-detached house using 12,000 kWh/year of heat:
| Heating System | Annual fuel cost | Annual service | Total/year |
|---|---|---|---|
| Gas combi boiler (93% eff.) | £950 | £80-120 | £1,030-1,070 |
| Oil boiler (90% eff.) | £930 | £100-150 | £1,030-1,080 |
| Electric boiler (100% eff.) | £3,130 | £0 | £3,130 |
| ASHP (COP 3.0) | £1,040 | £100-150 | £1,140-1,190 |
| GSHP (COP 4.0) | £780 | £100-150 | £880-930 |
When to Choose Each
Stick With Gas When
- Current gas boiler needs replacing
- Budget for heat pump is not available
- Property is poorly insulated (upgrade first)
- Plan to upgrade to heat pump within 10 years
Switch to Heat Pump When
- Property is well insulated (EPC C or better)
- BUS grant makes it affordable
- Replacing oil or LPG system
- New build or major renovation
Environmental Considerations
The UK grid carbon intensity has fallen from 500g CO2/kWh in 2012 to 136g in 2024 (DESNZ), making electric heating (especially heat pumps) increasingly clean. Gas and oil emit CO2 at the point of combustion — there is no way to reduce this. Hydrogen boilers are a potential future option for the gas grid but remain unproven at scale. For the lowest carbon footprint now, a heat pump with a green electricity tariff is the best option.
Related Calculators
- Boiler Size Calculator — calculate the right boiler output for your home
- Heat Loss Calculator — assess your property heat loss
Next up: related pages
How We Calculate This
Frequently Asked Questions
Mains gas remains the cheapest at about 7.33p/kWh (Ofgem Q3 2026). Oil (kerosene) costs 6-8p/kWh depending on purchase timing, but requires bulk buying and storage. Electricity at 26.11p/kWh (Ofgem Q3 2026 cap) is the most expensive per unit, but heat pumps multiply each unit by 2.5-4x, bringing effective cost to 7-10p/kWh, competitive with gas.
The Future Homes Standard (the 2026 edition of Approved Document L, applying to new homes in England from 24 March 2027) effectively prevents gas boilers in new-build homes by requiring very low carbon heating. Note: Part L 2021 (current Building Regulations) does not ban gas boilers but sets tighter efficiency standards. Existing homes can keep and replace gas boilers. There is no current ban on gas boiler replacements, but the government aims to phase them out by 2035. The BUS grant incentivises switching to heat pumps.
The standalone 2026 off-grid oil boiler ban was scrapped by the UK government in September 2023. Decarbonisation of new-build heating is now addressed through the Future Homes Standard (in force from 2025/26), which effectively prevents fossil-fuel heating in new-build homes through tight carbon limits. Replacement of existing oil boilers remains permitted, but homeowners are encouraged to switch to heat pumps with the £7,500 BUS grant.
Electric boilers are 99-100% efficient but electricity costs 3-4 times more per kWh than gas. Running an electric boiler costs roughly £2,500-3,500/year for a 3-bed house vs £800-1,200 for gas. Electric boilers suit small, well-insulated flats without gas supply, or as backup. Heat pumps are far more cost-effective for whole-house electric heating.
Heat pump on grid electricity produces about 40-50g CO2/kWh of heat (DESNZ 2024 grid factor 136g/kWh ÷ COP 3.0). Gas produces about 200g CO2/kWh (183g ÷ 92% efficiency), oil about 270g CO2/kWh (247g ÷ 90%), and direct electric heating about 136g CO2/kWh (same as grid). Heat pumps are the lowest-carbon option and will improve further as the grid decarbonises.
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Last updated: July 2026
Verified against UK standards · estimates only, confirm with your supplier.