The short answer
Mains gas is the cheapest and most convenient fuel for homes on the gas grid, but around 4 million UK homes are off the gas grid and rely on heating oil, LPG or other alternatives. Oil boilers typically have lower unit costs but require a storage tank and bulk delivery; LPG is piped like gas but costs more per unit. If you are off-grid, both have merit depending on your property. See new boiler costs for overall installation ranges.
Most UK homes are connected to the mains gas network, but roughly 4 million properties — predominantly rural — are not. For those households, the choice between heating oil and LPG is a significant decision affecting both running costs and the practicalities of the installation. Even homes on the gas grid sometimes consider LPG if they want flexibility. This guide compares all three on the factors that matter most.
Fuel type comparison at a glance
- Mains gas Cheapest per kWh; requires gas grid connection
- Heating oil (kerosene) Off-grid option; bulk delivery; needs 1,000+ litre tank
- LPG Off-grid; pipeline delivery; more expensive per kWh than gas
- Most efficient fuel type All comparable (boiler efficiency determines this)
- Off-grid best value Oil typically cheaper per kWh than LPG
- Grant available? BUS grant for heat pumps; ECO4 for some off-grid
Mains gas: the default for most UK homes
Natural gas (methane) distributed through the mains network is the most widely used heating fuel in the UK and, at current prices, among the cheapest per useful kilowatt-hour delivered to the radiators. Mains gas boilers — combis, system and regular types — are what most of this site covers. If you are connected to the gas grid, this is almost always the most cost-effective fuel option. The price is regulated, the supply is continuous (no delivery logistics) and the range of boiler models and installers is the widest of any fuel type. All gas work must be carried out by a Gas Safe registered engineer.
Heating oil (kerosene): the off-grid standard
Kerosene heating oil is the most common fuel for off-grid UK homes. Oil boilers work on the same condensing principles as gas boilers and achieve similar efficiencies (90%+). The key practical difference is the storage: you need an oil storage tank — typically 1,000–2,500 litres — on your property, usually outside, and you order bulk deliveries from a fuel distributor (typically annually or twice a year). Oil prices fluctuate more than gas prices and are tied to global energy markets. At most UK price levels, oil is cheaper per kWh than LPG but more expensive than mains gas. Oil boilers require an OFTEC-registered engineer (rather than Gas Safe) for installation and servicing.
| Fuel type | Typical p/kWh (2026) | Storage | Engineer registration |
|---|---|---|---|
| Mains gas | 6–8p | None (grid supply) | Gas Safe |
| Heating oil | 7–10p | 1,000+ litre tank on site | OFTEC |
| LPG | 9–14p | Bulk tank (rented or owned) | Gas Safe (LPG category) |
LPG: the gas-like off-grid option
Liquefied petroleum gas (LPG) is stored in a bulk tank on your property and distributed via pipework in a way that closely mirrors mains gas. LPG boilers are similar in design to natural gas boilers and Gas Safe registered engineers with LPG competence can install and service them. The main disadvantage is cost: LPG is typically 30–60% more expensive per kWh than mains gas. It is also more expensive than heating oil at most price points, though the difference narrows when oil prices spike. LPG may be preferred where an oil tank is not practical (planning constraints, groundwater sensitivity) or where a home is converting from gas and wants a similar user experience without a tank full of liquid fuel.
Switching fuel types
Switching from oil to LPG, or from either to mains gas (if the grid reaches your area), involves replacing the boiler and associated controls, and changes to the fuel supply infrastructure. Connecting to the mains gas network can cost £1,500–£3,000+ depending on your distance from the nearest gas main — though the long-term saving on fuel can make this worthwhile for rural homes that are close enough to the network. Ofgem and the gas transporter can advise on connection costs and feasibility. This is general information; fuel cost figures are illustrative at the time of writing and can change significantly with energy market conditions. All boiler and fuel system work should be carried out by the appropriate registered engineer — Gas Safe for gas and LPG, OFTEC for oil.
Replacing an off-grid boiler?
Get quotes from engineers registered for your fuel type — Gas Safe (LPG category) or OFTEC (oil). Compare costs and consider whether the BUS heat pump grant is relevant for your property.
Frequently asked questions
Is oil or LPG cheaper to heat a home?
At most UK price levels, heating oil is cheaper per kWh than LPG, though both are more expensive than mains gas. Prices fluctuate with global energy markets, so the gap varies. Both are significantly more expensive than mains gas when gas prices are low.
Can I convert from oil to mains gas?
Possibly, if the mains gas network is within a reasonable distance of your property. Connection costs vary with distance but typically run £1,500–£3,000+. The gas transporter for your area can advise on feasibility and cost.
Who installs oil boilers?
Oil boilers must be installed and serviced by an OFTEC-registered engineer (Oil Firing Technical Association). Gas Safe registration does not cover oil boiler work. Check engineer credentials at oftec.co.uk.
Is LPG the same as gas?
LPG (liquefied petroleum gas) is a different fuel from natural gas (methane) but behaves similarly when used in a boiler. LPG boilers are closely related to natural gas boilers but are set up for the different gas composition and pressure. Installation and servicing must be by a Gas Safe registered engineer with LPG competence.
Sources & further reading
- Energy Saving Trust — off-grid heating options, oil and LPG running costs
- GOV.UK — Boiler Upgrade Scheme eligibility for oil and LPG replacements
- OFTEC — Oil Firing Technical Association, oil boiler installation and engineer standards
- Gas Safe Register — LPG engineer competence requirements
This is general information, not advice for your specific property or installation. Costs, timescales and outcomes vary with your home, system condition and chosen engineer. All gas boiler work must be carried out by a Gas Safe registered engineer.