Find out exactly what an oil-filled radiator costs to run in the UK — from cost per hour through to the annual bill — using your own wattage and electricity unit rate.
Electric heating · Per hour to per year · UK p/kWh
Most oil-filled radiators are 800–2,500 W. The thermostat cycles it on and off, so real use is often lower.
Multiply the radiator's wattage in kilowatts (watts ÷ 1000) by the hours per day you use it, then multiply by your electricity unit rate in pence per kWh. Divide by 100 to get the daily cost in pounds. A 1,500 W radiator run for 5 hours a day at 24.5p/kWh costs about £1.84 per day — around £56 per month.
The thermostat cycles the element on and off, so actual costs are often 30–50% lower than the rated-power calculation. Use the calculator above as a useful upper bound, and set the thermostat to a lower temperature to reduce real spend.
You cannot change the laws of physics — electric heating always costs the same per kWh — but you can reduce the number of kWh you use and what you pay for each one.
The checklist below covers the most effective steps for UK households. A few of them cost nothing at all.
A 1,500 W oil-filled radiator costs about 36.75p per hour at 24.5p/kWh (1.5 kW × 24.5p = 36.75p). An 800 W model costs around 19.6p per hour and a 2,000 W model about 49p per hour. Enter your own wattage above for an exact figure based on your tariff.
At 5 hours a day, a 1,500 W oil-filled radiator costs roughly £1.84 per day at 24.5p/kWh. Over 7 days that is about £12.88 per week. The actual cost depends on how often the thermostat lets the element run — real-world use is often lower than the rated figure because the thermostat cycles off once the room reaches temperature.
Oil-filled radiators are not particularly cheap to run because they use mains electricity, which costs around 24.5p/kWh in the UK — roughly four times the cost of gas per kWh. However, because the oil retains heat and the thermostat cycles the element on and off, they are more efficient than a fan heater at maintaining a steady room temperature. They are best used to heat one room rather than the whole house.
Both types convert electricity to heat at 100% efficiency, so running cost depends on wattage and hours used — not the type. A 1,500 W oil-filled radiator costs exactly the same per hour as a 1,500 W fan heater. The practical difference is that oil radiators retain heat better after the thermostat cuts out, so they may need the element on for fewer hours to maintain the same room temperature. Fan heaters heat a room faster but lose heat as soon as they switch off.
Yes, significantly. The thermostat stops the heating element once the room reaches the set temperature, so the radiator is not drawing full power the entire time it is switched on. In a well-insulated room the element may only run for 40–60% of the time. This means real running costs are lower than the rated wattage suggests. Use the calculator above as the upper-bound worst case, and expect actual costs to be 30–50% lower with the thermostat set sensibly.
Gas central heating is considerably cheaper per unit of heat. In 2024, gas costs around 6p/kWh versus 24.5p/kWh for electricity — roughly a four-to-one cost ratio. A 1,500 W oil-filled radiator running 5 hours a day costs about £56 a month; equivalent gas-heated output would cost roughly £14 a month. Oil-filled radiators are a practical option for heating a single room occasionally, but running one as a primary heat source for a whole house would be very expensive.
