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Every home in the UK searches for a cheap yet effective means to keep itself warm. Of course, they’d want it without having to see their energy expenditure shoot through the roof. While some use their central heating systems, others use portable electric heaters. Especially oil-filled radiators.
They’re quiet, portable, and seem very cheap. But the real question is: are oil-filled radiators cheap to run, or do they secretly eat up more electricity than you think?
Let’s get straight to it. From how oil-filled radiators work to what they actually cost to operate on a daily basis – with simple examples, facts, and simple comparisons that make sense for everyday homes.
Let’s First Understand What an Oil-Filled Radiator Is
An oil-filled radiator is a portable electric heater that has a special kind of heat-retaining thermal oil in its metal fins. Don’t worry, however – the oil doesn’t burn. And it doesn’t require refills. It’s simply there to retain and radiate heat.
Here’s how they actually work:
- You plug it into an electrical outlet.
- The electricity warms the oil that it contains.
- The warm oil circulates through the fins. This then radiates heat into the room.
Unlike fan heaters, oil-filled radiators do not circulate air. They quietly and slowly give off heat, warming the room for hours – even after you’ve switched them off.
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How Much Electricity Does an Oil-Filled Radiator Use?
Well, it depends. Like many other devices, you can get oil-filled radiators in various wattages, which correspond directly to how much power they consume. And Wattage (W) on a radiator is the number of watts of power that it consumes at its full power.
Here is a quick overview:
- 600W radiator: uses 0.6 kWh per hour
- 1500W radiator: uses 1.5 kWh per hour
- 2000W radiator: uses 2 kWh per hour
- 2500W radiator: uses 2.5 kWh per hour
Electricity costs per unit in the UK for October 2025 are 26.35p/kWh. Thus, a 2000W radiator will consume roughly 53p/h if operating at its rated level. But oil-filled radiators turn on and off. This is due to the fact that they heat to the desired temperature. So, when in actual operation, they will only draw less than their rated power in the long run.
Factors That Affect Oil-Filled Radiator Running Costs
If you are questioning how much does an oil radiator cost to run day-to-day, it will largely depend on its wattage, how long you use it, and your electricity rate. Let us talk about the most important variables.
1. Oil-Filled Radiator Size and Power
The higher the watts, the higher the power (and of course, the larger your bills). Here is a handy reference:
| Radiator Size | Wattage | Best For |
| Small | Up to 600W | Small offices or bedrooms |
| Medium | 600W–1500W | Medium rooms such as lounges |
| Large | 1500W–2000W | Bigger living spaces |
| Extra Large | 2000W+ | Open-plan or poorly insulated rooms |
- A 600W oil radiator is cheaper to run but less warm.
- A 2000W or 2500W oil radiator warms a large room quicker, but consumes more power
2. Room Size and Insulation
The more insulation your room has, the less you will pay to run it. Heat blows quickly out of cold or older houses, causing your radiator to work longer.
Good insulation keeps the heat inside and makes the radiator cycle off more frequently, which will cost you less.
3. Usage Time
The cost of running increases with each additional hour of running. Consequently, running a 2000W radiator for two hours is roughly half the cost of running one for four.
Timers and thermostats are a huge time-saver. You can use them wisely to prevent wastage.
4. Electricity Prices
The present Ofgem energy price cap (Oct–Dec 2025) fixes electricity prices at:
- 26.35p per unit
- 53.68p per day standing charge
Your actual rate will be slightly different by supplier or area, but these are the typical rates to use for calculations.
Let’s Understand it With an Example
Let us calculate running costs using the 26.35p/kWh rate and a 4-hour daily usage period.
| Room Size | Radiator Wattage | Energy Used (kWh/day) | Electricity Cost | Total Daily Cost (incl. standing charge) |
| Small | 600W | 2.4kWh | £0.63 | £1.17 per day |
| Medium | 1500W | 6.0kWh | £1.58 | £2.11 per day |
| Large | 2000W | 8.0kWh | £2.11 | £2.65 per day |
| Extra Large | 2500W | 10.0kWh | £2.64 | £3.18 per day |
So, a 600W oil-filled radiator costs about £1.17 per day. While a 2000W oil-filled radiator costs around £2.65 per day, assuming 4 hours of daily use.
Weekly and Monthly Costs of Oil-Filled Radiators
| Room Size | Daily Cost | Weekly Cost | Monthly Cost (30 days) |
| Small | £1.17 | £8.19 | £35.10 |
| Medium | £2.11 | £14.77 | £63.30 |
| Large | £2.65 | £18.55 | £79.50 |
| Extra Large | £3.18 | £22.26 | £95.40 |
These figures include the daily standing charge and assume you’re using only the radiator as your main heat source.
600W Oil-Filled Radiator Running Costs
A 600W oil-filled radiator uses 0.6kW of electricity per hour.
With an average unit rate of electricity of 25p per kWh:
Cost = Power (kW) × Hours Used × Cost of Electricity
0.6 × 1 × £0.25 = 15p/hour
If you leave it on for 5 hours a day:
15p × 5 = 75p a day
So, a 600W radiator would be suitable for small offices or bedrooms. It’s ideal for supplementary heat and much cheaper to run than a 2kW heater if you just want a little warmth.
2000W Oil-Filled Radiator Running Cost
A 2000W oil-filled radiator is powerful enough for larger living rooms or rooms.
Again, let’s do its running cost calculation:
Cost = Power (in kW) × Hours Used × Electricity Rate
2 × 1 × £0.25 = 50p an hour
If you leave it on for 5 hours a day, that is £2.50 a day.
For 30 days in a month, that is around £75.
That is not always a “bargain” price. But if you are just heating one big room instead of your whole house, it may still be cheaper than having to turn on central heating.
2500W Oil-Filled Radiator Running Costs
It is one of the most powerful domestically available at 2500W (2.5kW).
Suitable for large or poorly-insulated areas but more costly.
Cost = Power (in kW) × Hours Used × Electricity Rate
2.5 × 1 × £0.25 = 62.5p/hour
Used 5 hours a day:
62.5p × 5 = £3.12/day, or approximately £94/month.
If you’ve got a big house, it’s expensive. But if you don’t use it that often, the convenience and heat might be worth paying for.
Tips to Make Oil-Filled Radiators Less Expensive to Run
Oil-filled radiators can be fairly cost-saving if used properly. Follow these tips to reduce your bill without losing any heat:
- Set the Thermostat Wisely: Heaters usually come with thermostats. So, fix your desired temperature and let it take care of the rest rather than running continuously.
- Use a Timer: Don’t warm an empty room. Leave it to turn on when you get up or return from work.
- Retain Heat: Keep the doors and windows closed to keep heat in. Even slight draughts will make your heater work extra hard.
- Combine with an Efficient System: If you’re eligible for an ECO4 boiler grant, upgrade your main central heating for free. Then use your oil-filled radiator only when needed – giving you:
- an efficient system for daily heating
- a portable, low-cost backup for extra warmth
Oil-Filled Radiators vs Central Heating (Gas Boilers)
Here’s the ultimate showdown most homeowners want to know:
| Factor | Oil-Filled Radiator | Gas Boiler (Modern A-rated) |
| Energy Source | Electricity | Gas |
| Running Cost (approx) | 26.35p per kWh | 6.29p per kWh |
| Efficiency | 100% (at point of use) | 90–94% |
| Heat Coverage | One room | Whole home |
| Initial Cost | £50–£150 | Can be £2,000+ (but free with ECO4) |
| Best For | Temporary/spot heating | Long-term home heating |
So, although an oil-filled radiator is cheaper to purchase, a new condensing gas boiler is much more economical for regular home heating.
And if you qualify for the ECO4 scheme, you can receive a new energy-efficient boiler for free, so it’s a long-term cost-saving.
Final Verdict: Are Oil-Filled Radiators Cheap to Run?
Yes – ONLY if:
- You’re warming one room for short periods of time.
- You’re making full use of thermostat and timer controls.
- The room is well-insulated.
No – if:
- You’re running more than one radiator for extended periods of time.
- You’re running them in large, draughty rooms.
- You already have sky-high electricity bills.
Summing up:
Oil-filled radiators are ideal for instant, localised warmth. They’re not the cheapest way to heat your whole house. But they’re a decent short-term or supplementary solution.
You could qualify for a grant for a new, free central heating system under the ECO4 Scheme if you’re low-income or have an old, inefficient boiler. Thus, saving you money on bills, carbon emissions, and continued warmth for literally zero cost.
Frequently Asked Questions
Slightly, yes. They hold heat even when turned off, using less power in the long term for constant heat. Ideal for extended use, as opposed to fan heaters that spill heat instantly.
Typically, 10–15 years with proper maintenance. The oil never needs to be changed. It just holds and releases heat to warm the rooms. So the radiators are very long-lasting and low-maintenance.
Yes. They have no naked parts and have in-built safety measures such as overheat protection, automatic switch-off, and tip-over sensors. Just avoid them getting in contact with other flammables.
Not particularly. A 2000W model costs about 53p an hour on current UK tariffs. And usually lower in practice, as it comes on and off once the room has been warmed.
Yes, for one room. But for the entire house, an efficient central heating system or free ECO4 boiler replacement would be more likely to cost less.
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