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) | ~6p | ~7p | ~25p | ~25p (but COP 3+) |
| Effective heat cost | ~6.2p/kWh | ~7.8p/kWh | ~25p/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 | 215g | 275g | 160-190g | 50-80g |
| 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.) | £900 | £80-120 | £980-1,020 |
| Oil boiler (90% eff.) | £930 | £100-150 | £1,030-1,080 |
| Electric boiler (100% eff.) | £3,000 | £0 | £3,000 |
| ASHP (COP 3.0) | £1,000 | £100-150 | £1,100-1,150 |
| GSHP (COP 4.0) | £750 | £100-150 | £850-900 |
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 under 150g in 2026, 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
How We Calculate This
Frequently Asked Questions
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Last updated: April 2026
All calculations are estimates. Verify with your supplier.