RapidHeat
Quick answer
A plug-in heater costs its power in kW multiplied by your electricity rate. At 27p per kWh, a 500W heater costs about 13.5p an hour and a 2kW heater about 54p an hour. They are cheap to run only when low-powered, used for short periods and used instead of heating the whole house.
What we checked: We used the standard kW × rate formula and an example UK unit rate of 27p per kWh. Check your own bill for your exact rate. Last reviewed 11 October 2026. How we research.
Key takeaways
- At 27p per kWh, a 1 kW heater costs about 27p an hour at full power and a 2 kW heater about 54p.
- Multiply its power in kW by your unit rate. For example, 1.5 kW × 27p = 40.5p per hour at full power.
- Storage heaters on an off-peak tariff often cost less for all-day heat.
- At 27p per kWh, a 2kW heater costs about 54p per hour at full power.
- Heating one room for a short time with an electric heater can be cheaper overall.
Running cost depends only on wattage, hours and your unit rate — not the brand. Using 27p per kWh (an example rate close to recent UK tariffs — check your own bill), here is what plug-in heaters cost to run.
Cost per hour by wattage
At full power and 27p per kWh:
- 500 W: 13.5p per hour
- 1,000 W (1 kW): 27p per hour
- 1,500 W (1.5 kW): 40.5p per hour
- 2,000 W (2 kW): 54p per hour
- 3,000 W (3 kW): 81p per hour
Do plug-in heaters use a lot of electricity?
Compared with most appliances, yes — a 2 kW heater uses as much power as about 20 LED lightbulbs. Thermostats reduce use once the room is warm, so real-world costs are usually lower than the full-power figures.
Are plug-in heaters cheaper than central heating?
Per unit of heat, gas central heating is usually cheaper. A plug-in heater can still cost less overall if it lets you heat one room for a few hours instead of the whole house. If you heat several rooms or for long periods, central heating normally wins.
How to keep costs down
Practical steps:
- Use the thermostat and timer rather than running at full power
- Close doors and block draughts in the room you are heating
- Choose the lowest power setting that keeps you comfortable
- Check your actual unit rate and use a smart meter display
Plug-in heater running cost table
| Heater power | Per hour | 5 hours a day | Per week (5h/day) | Winter (750 hours) |
|---|---|---|---|---|
| 400W | 10.8p | 54p | £3.78 | £81 |
| 600W | 16.2p | 81p | £5.67 | £121.50 |
| 800W | 21.6p | £1.08 | £7.56 | £162 |
| 1,000W (1kW) | 27p | £1.35 | £9.45 | £202.50 |
| 2,000W (2kW) | 54p | £2.70 | £18.90 | £405 |
| 3,000W (3kW) | 81p | £4.05 | £28.35 | £607.50 |
Electric heater vs gas central heating
Under recent UK price caps, electricity has cost roughly three to four times more per kWh than gas. A modern gas boiler converts around 90% of gas into heat, so each kWh of heat from gas is still much cheaper than from an electric heater.
The saving from a plug-in heater comes from heating less space, not from cheaper heat. If you heat one room for two hours instead of the whole house, you can use far less energy overall.
Seven ways to cut heater running costs
- Use the lowest wattage setting that keeps you comfortable
- Set the thermostat to 18–21°C rather than maximum
- Close the door and block draughts under it
- Use a timer so the heater is not left on in an empty room
- Use a smart plug to measure the real cost
- Draw curtains at dusk to keep heat in
- Consider an Economy 7 tariff only if you use electricity mainly at night
How much more do you pay for long sessions?
Costs scale directly with hours. A 1kW heater costs 27p for one hour, £1.08 for four hours and £2.16 for eight hours at 27p per kWh. Used every day for a month, eight hours a day, that is about £65. This is why plug-in heaters are best for short, targeted use rather than all-day heating.
Worked example: heating one room vs the whole house
Say you are home alone in the evening and only use the lounge. Running a 1.5kW heater for three hours uses 4.5kWh — about £1.22 at 27p per kWh. Heating a typical three-bedroom house with gas for the same three hours could use much more energy, though at a lower price per kWh. Which is cheaper depends on your house, boiler and tariffs, so a smart meter comparison over a few evenings gives the clearest answer.
Signs your heater is costing more than it should
- It runs flat out all the time and the room never feels warm — it is too small for the space
- You leave it on in empty rooms
- The room is draughty or the door is left open
- The thermostat is set to maximum
Is RapidHeat right for you?
Likely a good fit if you…
- Want to warm one small room or desk area
- Want to keep central heating off while you sit in one room
- Have no floor space for a radiator
- Value a 30-day money-back guarantee (per seller)
Probably not for you if you…
- Need to heat a large, open-plan or draughty room
- Expect it to replace central heating or cut bills dramatically
- Need a heater for a bathroom
- Need published wattage and certificates before buying
Frequently asked questions
Are plug-in heaters expensive to run?
At 27p per kWh, a 1 kW heater costs about 27p an hour at full power and a 2 kW heater about 54p. They are affordable for short use in one room but expensive as whole-home heating.
How much does a plug-in heater cost to run per hour?
Multiply its power in kW by your unit rate. For example, 1.5 kW × 27p = 40.5p per hour at full power.
Are plug-in heaters cheaper than storage heaters?
Storage heaters on an off-peak tariff often cost less for all-day heat. Plug-in heaters are better for short, on-demand heating.
How much does a 2kW heater cost per hour UK?
At 27p per kWh, a 2kW heater costs about 54p per hour at full power.
Is it cheaper to use an electric heater or central heating?
Heating one room for a short time with an electric heater can be cheaper overall. Per unit of heat, gas central heating is usually cheaper.
Do portable heaters use a lot of electricity?
High-power models (2–3kW) use a lot per hour. Low-power models use much less but also give out less heat.
What is the cheapest electric heater to run?
The lowest-wattage heater that keeps you warm enough, with a thermostat and timer to stop it running when not needed.
How much does a 1kW heater cost to run for 8 hours?
About £2.16 at 27p per kWh at full power.
Are oil-filled radiators cheap to run?
They cost the same per kWh as other electric heaters. Because they hold heat, a thermostat may switch them off more often.
Sources and further reading
Read our full RapidHeat Heater review for specifications, pros and cons and our verdict.