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Quick answer
Per unit of heat, gas central heating is much cheaper than a plug-in electric heater. Under the October to December 2026 price cap, electricity costs 26.32p per kWh and gas 7.97p per kWh. An electric heater turns every kWh into heat, while a condensing boiler at around 90% efficiency delivers roughly 0.9kWh of heat per kWh of gas, so heat from the boiler costs roughly 9p per kWh against about 26p from the electric heater. A plug-in heater can still make sense for heating one small room for a short time when the rest of the house would otherwise need heating.
Key takeaways
- At October 2026 capped rates, electricity is over three times the price of gas per kWh.
- Allowing for boiler efficiency, heat from gas costs roughly a third of heat from a plug-in heater.
- Electric heaters are cheapest only when used briefly in one room instead of heating the whole house.
- Oil-filled radiators, fan heaters and convectors all cost the same per kWh of heat; they differ in how they deliver it.
- Heat pumps are different: they deliver several kWh of heat per kWh of electricity.
The unit rates
Ofgem’s October to December 2026 cap for Direct Debit customers sets average unit rates of 26.32p per kWh for electricity and 7.97p per kWh for gas, before standing charges. These are averages; your region and tariff may differ.
Working out the cost of heat
Plug-in electric heater. 1kWh of electricity gives 1kWh of heat. Cost: about 26p per kWh of heat.
Gas boiler. A well-set-up condensing boiler delivers roughly 0.9kWh of heat per kWh of gas. Cost: 7.97p divided by 0.9, roughly 9p per kWh of heat.
So a 2kW electric heater running for an hour costs about 53p. Delivering the same 2kWh of heat from the boiler costs around 18p.
When an electric heater can still be the better choice
The comparison changes if the alternative is heating the whole house to warm one room. If you work from home in a small study and everyone else is out, running a small electric heater for a few hours can cost less than running the whole central heating system. The key is how many rooms the boiler would otherwise heat. Using TRVs to turn down unused rooms narrows the gap. See thermostat and TRV settings for winter and smart radiator valves.
Types of electric heater
Oil-filled radiators, convector heaters and fan heaters all turn electricity into heat at the same rate. Fan heaters warm a room quickly; oil-filled radiators give steadier heat. None is cheaper per kWh. Infrared panels heat objects and people directly and can feel warmer at lower air temperatures, but still cost the same per kWh.
Heat pumps are different
Heat pumps move heat rather than generate it and typically deliver several kWh of heat for each kWh of electricity. That changes the maths entirely. See hybrid heat pumps explained.
Get the boiler working efficiently
The gas figure assumes your boiler is burning and condensing properly. A poorly set-up or unserviced boiler narrows the gap. See boiler flow temperature settings and book an annual boiler service.
Book with Gasmaster
Want your gas heating running as efficiently as possible? Gasmaster Plumbing & Heating, Gas Safe registered (220932), services boilers across Stoke-on-Trent, Newcastle-under-Lyme and Biddulph. Book through our boiler service booking page.
Frequently asked questions
Is it cheaper to use an electric heater or turn the heating on?
For one small room for a short time, possibly the heater. For the whole house or long periods, the gas boiler is usually much cheaper.
How much does a 2kW heater cost per hour?
At the October 2026 capped rate, around 53p per hour at full power.
Are oil-filled radiators cheaper to run?
They cost the same per kWh as other electric heaters but give steadier heat.
Sources
- Ofgem, October to December 2026 energy price cap (ofgem.gov.uk)
- Energy Saving Trust, heating options (energysavingtrust.org.uk)
Related services
Abdul runs Gasmaster Plumbing & Heating and has worked on boilers, heating and gas appliances across Stoke-on-Trent since 2005. He is Gas Safe registered (reg. 220932), and these articles come from his day to day work in homes and businesses across Staffordshire, Cheshire and Derbyshire.
