The short answer
A 2 kW electric heater costs 52.6p an hour, £2.11 for a 4-hour evening and about £63 a month if you run it 4 hours every day. A 1 kW heater costs half of that; a 3 kW one costs 79p an hour. Oil-filled, fan, ceramic, convector and panel heaters all cost the same per hour at the same wattage — the only thing that lowers the bill is running fewer hours at a lower setting.
1 kW heater, per hour
2 kW heater, per hour
3 kW heater, per hour
2 kW, 4-hour evening
Cost per hour by wattage
| Heater power | Per hour | 4 hours | 8 hours | Per month (4 h/day) |
|---|---|---|---|---|
| 500 W | 13.2p | 52.6p | £1.05 | £15.79 |
| 1,000 W | 26.3p | £1.05 | £2.11 | £31.58 |
| 1,500 W | 39.5p | £1.58 | £3.16 | £47.38 |
| 2,000 W | 52.6p | £2.11 | £4.21 | £63.17 |
| 2,500 W | 65.8p | £2.63 | £5.26 | £78.96 |
| 3,000 W | 79.0p | £3.16 | £6.32 | £94.75 |
These are worst-case figures with the element on continuously. A heater with a working thermostat in a room that has reached temperature typically runs the element 40–70% of the time, so real bills land below these numbers.
Electric heater vs gas central heating vs heat pump
At the current cap, gas costs 7.97p/kWh and electricity 26.32p/kWh. A modern condensing boiler turns about 90% of the gas into heat, so a kWh of heat from gas costs roughly 8.9p against 26.3p from any electric heater — about three times cheaper. A heat pump delivers around 3 kWh of heat per kWh of electricity, so its heat costs roughly 8.8p per kWh, on a par with gas.
The case for an electric heater is therefore not the price per kWh; it is heating one room instead of the whole house. Running a 1.5 kW heater for 4 hours (£1.58) is often cheaper than firing a 24 kW boiler to warm every radiator for the same evening.
Why 'efficient' electric heaters do not exist (and what does save money)
Resistive heating is already 100% efficient: all the electricity that goes in comes out as heat. A £200 heater and a £20 heater of the same wattage produce identical heat for identical money. What differs is how well they stop: an accurate electronic thermostat, an eco mode that steps the power down, a timer, and open-window detection all cut the minutes the element is on.
Oil-filled radiators feel cheaper because the oil keeps radiating after the element cuts out, and because people run them on low for long stretches. Ceramic fan heaters feel expensive because they are usually set to full to warm a room fast. Both are the same price per kWh.
The cheapest way to stay warm: heat the person
An electric blanket draws 60–150 W — 1.6p to 3.9p an hour — and a heated throw about 100–160 W. A desk heater under a table at 500 W costs 13p an hour. If you are sitting still, these beat any room heater by a factor of ten. See our electric blanket guide for the running costs of individual models.
What the Ofgem cap actually is
The price cap sets the maximum unit rate and standing charge a supplier can charge default-tariff customers in Great Britain. For 1 October to 31 December 2026 the electricity unit rate is 26.32p/kWh (GB average, Direct Debit) with a 54.83p daily standing charge; VAT on electricity was removed for this period and until 31 March 2027. The cap changes every quarter, so we update this page with each Ofgem announcement. If you are on a fixed tariff, use your own unit rate in the calculator.
Running cost of the heaters we recommend
| Product | per hour | per 4-hour evening | per month |
|---|---|---|---|
| Dreo Heater 316 (1,500 W ceramic fan heater, remote) | 39.5p | £1.58 | £47.38 |
| De'Longhi Dragon 4 TRD40820T oil-filled radiator (2 kW) | 52.6p | £2.11 | £63.17 |
| VonHaus 11-fin oil-filled radiator, 2,500 W with 24 h timer | 65.8p | £2.63 | £78.96 |
| Russell Hobbs 13-inch oscillating ceramic heater, 2 kW | 52.6p | £2.11 | £63.17 |
| Warmlite WL44001 fan heater, 1,000 / 2,000 W | 52.6p | £2.11 | £63.17 |
| QEXREED 2,000 W PTC tower heater with ECO mode and remote | 52.6p | £2.11 | £63.17 |
| Belaco 2,000 W convector heater, 3 settings | 52.6p | £2.11 | £63.17 |
| Devola 2,500 W smart glass panel heater (Wi-Fi, wall or free-standing) | 65.8p | £2.63 | £78.96 |
| Amazon Basics 1,800 W ceramic space heater | 47.4p | £1.90 | £56.85 |
| Russell Hobbs 7-fin oil-filled radiator, 1,500 W | 39.5p | £1.58 | £47.38 |
| Midea 11-fin oil radiator, 2,300 W | 60.5p | £2.42 | £72.64 |
Your own numbers
per hour
per day
per month (30 days)
Frequently asked questions
Does leaving an electric heater on low all day cost less than blasting it for an hour?
It depends on the room. Low all day keeps the walls and furniture warm, so the thermostat cycles the element off for long stretches; in a well-insulated room this can use less energy than reheating from cold every evening. In a draughty room the heat leaks out as fast as it goes in and running all day costs more. Measure it: a 1 kW setting for 10 hours is £2.63 at most; a 2 kW blast for 2 hours is £1.05.
How much does it cost to run an electric heater overnight?
A 1 kW setting for 8 hours is £2.11 at 26.32p/kWh; 2 kW for 8 hours is £4.21. For a bedroom, a 600–750 W oil radiator on a thermostat (about £1.26–£1.58 per 8 hours at full power, less with the thermostat cycling) or an electric blanket (around 15–30p a night) is the sensible choice.
Are infrared panel heaters cheaper to run?
Per kWh, no — a 600 W infrared panel costs 15.8p an hour, the same as any 600 W heater. They can feel cheaper because they warm people and surfaces directly, so you may be comfortable at a lower air temperature and run fewer watts. The saving comes from using a lower wattage, not from the technology.
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