How much does an electric garage heater cost per hour to run in the UK?
Dimplex's RUG3TS workshop heater, sold for garages, has two settings of 1.5 and 3 kilowatts, so it costs 39p or 79p an hour at the Ofgem cap rate of 26.32p per kWh. Four hours on full uses 12 kilowatt hours and costs £3.16, and two of those sessions a week come to about £27.37 a month. Keeping a garage above freezing is much cheaper, because a 3ft tubular heater at 120 watts costs 3.2p an hour and its thermostat switches it off whenever the air is warmer than the setting.
What a garage heater draws
Garage heaters come in two kinds that do very different jobs, and the cost per hour is about 25 times apart.
The first kind warms you while you work. Dimplex sells the RUG3TS as a workshop heater, described in its 2026 trade catalogue as perfect for workshops and garages, with two heat settings of 1.5 and 3 kilowatts, overheat protection, a tilt switch and an IP21 rating. There is no thermostat listed, so whichever setting you choose is what it draws for every minute it is on. Three kilowatts is also about the most a 13 amp plug can deliver, so this is as powerful as a portable heater gets without a dedicated circuit.
The second kind keeps the frost off. Dimplex's ECOT tubular heaters are rated at 40 watts per foot of length, from the 1ft ECOT1FT at 40 watts to the 6ft ECOT6FT at 240 watts. They have an adjustable thermostat with a frost protection setting, an IPX4 rating against splashing, and Dimplex lists them for jobs from airing cupboards to greenhouses.
We use the RUG3TS on full at 3 kilowatts as the everyday figure for a four hour session in the garage.
Work it out for your own garage fan heater, 3kW
Type in the wattage from the plate on the back, then your own unit rate. The numbers update as you type.
Working in the garage, per hour and per session
| Heater | Power | Per hour | Four hour session | Two sessions a week, per month |
|---|---|---|---|---|
| RUG3TS workshop heater on full | 3,000 W | 79p | £3.16 | £27.37 |
| RUG3TS on its half setting | 1,500 W | 39p | £1.58 | £13.69 |
| Full for 30 minutes, then half | mixed | 44p on average | £1.78 | £15.40 |
| 2kW fan heater or oil filled radiator | 2,000 W | 53p | £2.11 | £18.25 |
The third row is the one worth copying. A cold garage needs the full output while the air and the bench come up to something bearable, and once you are moving about the half setting is often enough. Four hours run that way uses 6.75 kilowatt hours instead of 12, which saves £1.38 a session.
| Appliance | Typical draw | Usage we assume | Per hour (UK) | Per usage (UK) | Per month (UK) | Per hour (US) |
|---|---|---|---|---|---|---|
| Garage fan heater, 3kW | 3000 W | per 4 hour workshop session on full | 79.0p | £3.16 | £27.37 | 55.0 cents |
Rates: Ofgem cap 1 October to 31 December 2026 at 26.32p per kWh (source), EIA residential average June 2026 at 18.34 cents per kWh (source). Checked 2026-09-22.
Keeping it frost free
| Tubular heater | Power | Per hour | 24 hours flat out | A month flat out |
|---|---|---|---|---|
| ECOT1FT, 1ft | 40 W | 1.1p | 25p | £7.66 |
| ECOT2FT, 2ft | 80 W | 2.1p | 51p | £15.33 |
| ECOT3FT, 3ft | 120 W | 3.2p | 76p | £22.99 |
| ECOT4FT, 4ft | 160 W | 4.2p | £1.01 | £30.66 |
| ECOT6FT, 6ft | 240 W | 6.3p | £1.52 | £45.99 |
The flat out columns are a ceiling, because the thermostat cuts the heater out whenever the garage is above its setting. How far below the ceiling you land depends on the weather and how well the garage holds heat, so we cannot give one honest number for it. What we can say is that every hour the thermostat keeps a 3ft heater off saves 3.2p.
A whole day of a 3ft tubular heater running flat out costs 76p, which is slightly less than a single hour of the workshop heater on full. If what you actually need is a garage where paint, pipes and stored garden chemicals do not freeze, the small heater does that job for a fraction of the cost.
Why a garage swallows heat
Dimplex prints a short line under its portable heaters which sums up the problem, saying they are only suitable for well insulated spaces or occasional use. Many garages are neither insulated nor sealed. A single skin brick wall, an uninsulated roof and a metal up-and-over door all lose heat fast, which is why running a heater all day in one is so expensive for so little warmth.
The sensible approach follows from that. Treat the garage heater as something that warms you and your bench for the hours you are there, rather than something that warms the building. Point a fan heater at where you stand, close the main door and work with the side door shut, and switch it off when you walk back into the house. For anything longer, such as a garage converted into a gym or an office, insulating it first is likely to save more than any choice of heater.
What the oil filled radiator is good for
People often move a spare oil filled radiator into the garage, and at 2 kilowatts it costs 53p an hour, two thirds of the workshop heater on full. It warms more slowly than a fan heater, which suits a small insulated workshop used for a whole afternoon better than a cold garage you are in for half an hour. For quick jobs the fan heater wins because it heats the air around you within minutes.
Where the real savings are
- Use full power to warm up, then drop to the half setting. On a four hour session that saves about £1.38.
- Heat the hours you are out there and nothing more. A workshop heater left on in an empty garage for an hour costs 79p for nothing.
- Pick the shortest tubular heater that covers what needs protecting. Every foot adds 1.05p an hour.
- Set the tubular heater thermostat to frost protection rather than a comfortable temperature, because its job is to stop things freezing.
- Draught strip the side door and the gap under the main door before buying a bigger heater.
What this costs in the United States
At the EIA residential average of 18.34 cents per kilowatt hour, a 3 kilowatt heater costs 55 cents an hour and $2.20 for a four hour session. In California at 34.74 cents that hour costs $1.04, and in Texas at 15.94 cents it costs 48 cents. A 120 watt tubular heater running flat out for 24 hours costs 53 cents at the national average.
Common questions
How much does it cost to heat a garage per month?
It depends almost entirely on how often you are out there. Two four hour sessions a week with a 3kW heater on full use about 104 kilowatt hours a month, which is £27.37 at the cap rate. Keeping the garage frost free with a 120 watt tubular heater costs at most £22.99 a month if it never switches off, and less in practice because the thermostat cuts it out on milder days.
Is it expensive to heat a garage?
Occasional heating is not. A Saturday afternoon at 3kW costs £3.16. What gets expensive is trying to keep an uninsulated garage warm all day, because eight hours at 3kW is £6.32 and most of that heat leaves through the door, the roof and the single skin walls. Dimplex itself says its workshop heater is only suitable for well insulated spaces or occasional use.
How much does it cost to run a tubular heater?
Dimplex tubular heaters draw 40 watts for every foot of length, so each foot costs 1.05p an hour. A 2ft heater at 80 watts costs 2.1p an hour and 51p for a full day flat out, and a 3ft heater at 120 watts costs 3.2p an hour and 76p a day. The thermostat brings those down whenever the garage is above the setting.
Is a 2kW heater cheaper than a 3kW heater in a garage?
Per hour, yes. A 2kW heater costs 53p an hour against 79p for 3kW. Whether it is cheaper overall depends on whether it ever gets the space warm, and in a draughty garage a smaller heater can run for longer and still leave you cold. Running a 3kW heater on full for the first half hour and then on 1.5kW is often the better compromise.