How much does a 2kW heater cost to run?
At the Ofgem price cap unit rate of 26.32p per kWh, a 2kW electric heater costs about 53p an hour when it is running flat out. Four hours on a winter evening is about £2.11, and doing that every day for a month adds roughly £63.17 to your bill.
That is the worst case. Most heaters have a thermostat, and once the room is warm the element switches on and off, so the real cost is often noticeably lower.
Prices last checked: 26 September 2026 · Source: Ofgem energy price cap, 1 October to 31 December 2026 · Great Britain average, standard variable tariff, paid by Direct Debit
2kW heater cost per hour, day and month
Many "2kW" heaters have two or three power settings. The table uses the cap unit rate and assumes 4 hours of use a day with the element on the whole time, so treat it as a ceiling rather than a forecast.
| Setting / heater | Energy per hour | Cost per hour | Per day (4 h) | Per 30 days |
|---|---|---|---|---|
| Low setting (1kW) | 1 kWh | 26p | £1.05 | £31.58 |
| Medium setting (1.5kW) | 1.5 kWh | 39p | £1.58 | £47.38 |
| 2kW heater on full | 2 kWh | 53p | £2.11 | £63.17 |
| 2.5kW convector on full | 2.5 kWh | 66p | £2.63 | £78.96 |
| 3kW fan heater on full | 3 kWh | 79p | £3.16 | £94.75 |
Why the thermostat matters more than the wattage
A 2kW rating tells you how fast the heater uses electricity while the element is on. It does not tell you how long the element stays on. With the thermostat set to a sensible temperature, the heater runs hard for the first stretch while the room warms up, then cycles to keep it there. How much it cycles depends on how quickly the room loses heat. Draughts, single glazing, an open door to a cold hallway or an outside wall all keep it running.
So two people with the same 2kW heater can have very different bills. If the element is only on for 30 minutes in each hour, the hourly cost halves to about 26p. If the room leaks heat and the thermostat never cuts out, you pay the full 53p every hour.
Oil-filled radiator, convector or fan heater: which is cheapest?
Per hour at the same wattage, they cost the same. Every plug-in resistive heater turns almost all of its electricity into heat, so 2kW of electricity is 2kW of heat whether it comes from fins full of oil, a convector panel or a fan. The differences are about how the heat arrives:
- Fan heaters warm the air near you quickly. They suit short bursts, such as ten minutes in a cold bathroom or home office, but the warmth disappears soon after you switch them off.
- Oil-filled radiators take longer to warm up and keep giving off heat after the element cycles off. That makes the thermostat cycling smoother. It can feel cheaper, but only because the element is on less often, not because the watts are better.
- Convector heaters sit in between. They warm the whole room's air and go cold fairly quickly.
If you see a plug-in heater advertised as "cheaper to run" with no mention of a heat pump, the saving comes from a lower wattage or a better thermostat, not from extra efficiency. See our oil-filled radiator page for the cycling maths in more detail.
2kW heater vs gas central heating
Per unit of energy, mains gas is much cheaper than electricity under the cap: 7.97p per kWh for gas against 26.32p for electricity. A gas boiler does not turn every kWh of gas into useful heat. If you assume around 90% for a modern condensing boiler, a kWh of heat from gas costs roughly 8.9p. From a plug-in heater it costs 26p.
So gas wins per kWh of heat. The heater only wins when you need far less heat. Running the 2kW heater for four hours uses 8 kWh and costs £2.11. At the cap gas rate, that same money buys about 26 kWh of gas. If your boiler would burn more gas than that heating the whole house for the same evening, heating one room with the heater is the cheaper option. If you are only warming one room with the door shut and nobody else is home, it often is. For a family spread across the house, it usually is not.
To find out, read your gas meter before and after an evening with the central heating on, and compare. Gas meters in newer homes usually read in cubic metres, so your bill's conversion factor turns that into kWh. Older imperial meters read in hundreds of cubic feet.
Common mistakes when working out heater costs
- Adding the standing charge to the heater. The daily standing charge (54.83p a day at the cap) is fixed, so switching the heater off does not change it. Leave it out when comparing appliances.
- Assuming full power all day. "2kW × 24 hours" is only realistic in an empty, unheated outbuilding in winter.
- Using last winter's price. The cap changes every quarter. The previous period's rate was 26.11p; the next announcement is due on 25 November 2026.
- Running it from an extension lead. This is a safety problem rather than a cost one. A 2kW heater draws a lot of current, so plug it directly into a wall socket.
Cheaper ways to stay warm
- Heat the person, not the room. An electric blanket or heated throw uses a small fraction of a 2kW heater's power.
- Use the timer, not the "on" position. Twenty minutes to take the chill off before you sit down, then the thermostat's lowest comfortable setting.
- Close the door and block draughts. Anything that slows heat loss cuts the thermostat's on-time directly.
- Use the lower setting. Once the room is warm, 1kW is often enough to hold the temperature, at half the hourly cost.
Limits of this estimate
The cap figure is a Great Britain average for Direct Debit customers on a standard variable tariff. Your own rate depends on your region, how you pay and whether you are on a fixed deal. Economy 7 and other time-of-use tariffs have different day and night rates. Northern Ireland is not covered by the Ofgem cap. The duty-cycle figure you enter is a guess until you measure it.
Frequently asked questions
How much does a 2kW heater cost to run overnight?
Eight hours at full power uses 16 kWh, which is about £4.21 at the cap rate. With a thermostat holding a bedroom at a modest temperature it will usually be less. If you are on Economy 7, most of those hours may fall in the cheaper night window, so check your night rate.
Is a 2kW heater cheaper than central heating?
Only when it replaces a lot of gas. Gas is cheaper per kWh of heat, so the heater wins when you heat one room instead of a whole house, not when both are running.
Does a 2kW heater use 2 kWh every hour?
Only if the element is on for the whole hour. With a thermostat it uses less once the room reaches the set temperature.
Is a 3kW heater more expensive than a 2kW heater?
Per hour on full power, yes: about 79p against 53p. But a 3kW heater warms a room faster, so its thermostat may cut out sooner. In a small room the difference over an evening can be smaller than the ratings suggest.