What an electric boiler costs to buy and run
An electric boiler is cheap to fit and expensive to feed. Installation is comparable to gas (around £1,500 to £4,500), but running it costs roughly £1,700 a year for a typical home against £620 to £1,260 on gas. The calculator below lets you compare the two for your own heat demand and rate, so you can see exactly how big the gap is for your home.
What would an electric boiler cost you to run?
Set your yearly heat demand and rates. We compare an electric boiler against a gas one for the same warmth, so you see the real gap.
Running cost a year (fuel)
Fuel only; both pay standing charges. Electric boiler 99% efficient, gas 90%.
Default rates: Ofgem cap 24.67p electricity / 5.74p gas (1 Apr to 30 Jun 2026). Running-cost figures consistent with Checkatrade/Boiler Guide 2026. Verified June 2026.
The 99% efficiency trap
Electric boiler marketing leans hard on one number: 99 to 100% efficient, versus around 90% for a gas boiler. It is true. It is also nearly irrelevant to your bill, because efficiency tells you how much of the fuel becomes heat, not how much that fuel costs. A 99% efficient boiler running on fuel that costs four times more is still far more expensive to run.
This is the single most misunderstood point in home heating. "More efficient" feels like "cheaper", so people assume electric must save money. The price of the fuel swamps the efficiency difference many times over. Understanding that one distinction is what stops a costly mistake.
When an electric boiler actually makes sense
Despite the running cost, there are homes where an electric boiler is the right call, almost always because the cheaper alternative is not available:
- ✓No mains gas. Around 15% of UK homes are off the gas grid. Against oil, LPG or old storage heaters, an electric boiler can be competitive and far simpler;
- ✓Flats and small, low-demand homes. When you use little heat, the running-cost gap is smaller in pounds, and the space savings (no flue, no gas pipe) matter more;
- ✓Low-maintenance needs. No annual gas safety check, no flue, no carbon-monoxide risk, useful for landlords of small units or hard-to-flue properties.
If you do have gas and normal demand, gas or a heat pump will almost always cost less to run. The electric boiler is a niche tool, excellent in its niche, expensive outside it.
The insider view: a heat pump is the electric boiler done right
Here is the point that reframes the whole decision. If your reason for going electric is "I have no gas" or "I want to stop burning fossil fuels", an electric boiler is the least efficient way to do it. A heat pump runs on the same electricity but delivers about three units of heat per unit of power, where an electric boiler gives one. So a heat pump's running cost is roughly a third of an electric boiler's for the same warmth.
The order of preference for electric heating For an off-gas home, the running-cost ranking is usually: heat pump (cheapest), then an electric boiler on a cheap off-peak tariff, then an electric boiler on the standard cap (most expensive). The electric boiler only beats the heat pump on upfront cost and on homes where a heat pump physically cannot be fitted. So before defaulting to an electric boiler, always check whether a heat pump fits, the £7,500 grant often closes the upfront gap.
What to actually do
Check if you have gas first
If mains gas is available and your demand is normal, a gas boiler or heat pump will almost certainly cost less to run.
If off-gas, price a heat pump too
A heat pump uses the same electricity far more efficiently. The £7,500 grant often makes its upfront cost competitive.
Check your electrics
Switching to electric can need rewiring and a larger fuse. Get an electrician to confirm your supply can take the load before you buy.
Pair it with a cheap tariff
If you do fit an electric boiler, an off-peak or time-of-use tariff is the single biggest lever on its running cost.
The bottom line
An electric boiler is cheap to fit, compact, low-maintenance and almost 100% efficient, but it costs three to four times more to run than gas because electricity is the dearer fuel. That makes it a strong choice for off-gas flats and low-demand homes, and a poor one for a typical gas-connected house. And if your goal is electric heating, check a heat pump first: it is the efficient way to heat with electricity, and the grant often makes it affordable.
Electric boiler FAQ
The Selectra expert answers your questions
Around £1,700 a year for a typical home, against roughly £620 to £1,260 for the same home on gas. The gap is not about the boiler, it is about the fuel: at the 2026 price cap, electricity is about 24.67p per kWh versus 5.74p for gas, so each unit of heat from electricity costs three to four times more, even though the electric boiler is more efficient.
About £1,500 to £4,500, with an average near £3,250, broadly comparable to a gas boiler. It is often simpler to fit because there is no flue or gas supply, but switching from gas to electric can need rewiring and possibly a larger main fuse, because the boiler draws a lot of power at once. Always get this checked before committing.
When you have no mains gas (about 15% of UK homes), in a flat or small home with low heating demand, or as a low-maintenance option where a gas supply is not practical. It needs no annual gas safety check, no flue and produces no carbon monoxide. For a typical gas-connected home with normal demand, gas or a heat pump is usually cheaper to run.
Electric boilers typically range from 6 kW to 14 kW. A common rule of thumb is about 1.5 kW per radiator, so a flat with 8 radiators needs roughly a 12 kW unit. They are usually heating-only or paired with a hot-water cylinder; a few combi-style electric boilers exist but flow rates are modest.
If you are going electric for heating, a heat pump is almost always cheaper to run than an electric boiler, because it moves about three units of heat per unit of electricity (an electric boiler gives one). The heat pump costs far more upfront, but the £7,500 grant and lower running cost usually win over time. See combi vs heat pump cost. An electric boiler makes most sense where a heat pump will not fit.