How Much Electric Do Electric Heaters Use

Electric heaters can be a practical solution for heating rooms quickly, especially during the colder months or in homes without central heating. However, they are also known for their relatively high running costs compared to other heating options. Understanding how much electricity your electric heater uses depends on several factors including its wattage, size, usage time, and energy tariff. For homeowners across the UK, knowing these details helps make more informed choices about which heating method is most cost-effective and energy-efficient.

How Electric Heaters Work

Electric heaters convert electrical energy into heat using resistance heating elements. When electricity passes through the element, it encounters resistance, which produces heat. The efficiency of this process is technically 100 per cent in terms of conversion, meaning all the electricity consumed becomes heat. However, this does not necessarily make them the most economical form of heating, as electricity is usually more expensive per kilowatt-hour (kWh) than gas.

Most domestic electric heaters are portable plug-in units rated between 500 watts and 3,000 watts. Fixed models, such as electric radiators or panel heaters, operate at similar power levels but are controlled via thermostats or timers for greater energy efficiency. The key to understanding how much electricity they use lies in the heater’s power rating, how long it runs, and the cost of electricity per kWh on your tariff.

Calculating Energy Consumption

To calculate how much electric a heater uses, you multiply its power rating in kilowatts by the number of hours it runs. For example, a 2 kW heater running for one hour consumes 2 kWh of electricity. If your electricity tariff is 30 pence per kWh, that heater would cost about 60 pence per hour to run.

A small 1 kW convector heater running for three hours a day would use 3 kWh per day, costing roughly 90 pence per day at the same tariff rate. Over a month, that equates to around £27. These figures are estimates, as your actual cost will depend on your supplier’s unit rate and whether you are on a variable or fixed tariff.

It is worth noting that while electric heaters are efficient in converting power to heat, they can become expensive if used for long periods or to heat large spaces. For this reason, they are often best suited for supplementary heating in specific rooms rather than as a whole-home heating system.

Types of Electric Heaters and Their Efficiency

Different types of electric heaters use electricity in slightly different ways, and their efficiency in maintaining warmth varies. Fan heaters, for instance, use a heating element and a fan to blow warm air into a room. They heat up quickly but also cool down fast once turned off, making them good for short bursts of heat. However, they are less efficient for sustained heating because they rely on constant power use.

Convector heaters warm the air around them and allow it to circulate naturally throughout the room. These heaters maintain temperature more evenly but may take longer to heat up. Oil-filled radiators retain heat for longer even after being switched off, as the oil inside stays warm and continues to emit heat gradually. While they may take longer to reach full temperature, they are more cost-effective for longer heating periods.

Infrared and halogen heaters, which emit radiant heat, directly warm objects and people rather than the air. These can be very efficient for targeted heating, such as warming a person sitting in one area of a room, but are less effective at heating larger spaces.

Smart electric heaters and thermostatically controlled models can significantly reduce running costs by automatically adjusting output to maintain a consistent temperature rather than running continuously at full power.

Comparing Electric Heaters with Other Heating Options

Electric heaters are convenient, portable, and easy to install. Unlike gas central heating, they require no flues or pipework, and they are almost silent in operation. However, the main disadvantage is running cost. The average cost per kWh of electricity in the UK is about three times higher than gas, meaning electric heating generally costs more to run.

For comparison, a typical gas boiler provides heat at roughly 10p per kWh, whereas electric heaters may cost around 30p per kWh, depending on your tariff. This difference can make electric heating up to three times more expensive for the same amount of heat. That said, electric heaters are often used only in specific rooms and for limited periods, which can still make them cost-effective for small spaces or occasional use.

In some modern, well-insulated homes or flats without access to gas, electric heating can still be viable, particularly when combined with smart controls and off-peak tariffs. Some users also pair electric heating with renewable energy sources, such as solar panels, to offset costs.

How to Reduce Running Costs

The best way to reduce electricity consumption from electric heaters is to use them strategically. Start by heating only occupied rooms and closing doors to retain heat. Setting the thermostat to a moderate temperature rather than maximum output also prevents unnecessary energy use.

If your heater has a timer, schedule it to operate only when needed, such as in the morning or evening. For long-term savings, consider upgrading to heaters with thermostatic controls or smart energy management systems. These devices automatically regulate heat output and can be programmed through mobile apps to prevent overuse.

Improving insulation in your home can also make a significant difference. Draft-proofing windows and doors, adding thicker curtains, and ensuring proper loft insulation reduce the amount of heat lost and therefore the amount of electricity required to maintain a comfortable temperature.

Impact of Heater Size and Room Type

Matching heater size to the room is another important factor. A heater that is too small will struggle to maintain warmth, leading to continuous operation and higher energy use. Conversely, an oversized heater may use more electricity than necessary.

As a general guideline, a 1 kW heater is sufficient for a small bedroom or study of around 10 square metres, while a 2 kW to 2.5 kW heater is better for a medium-sized living room. Large open spaces or poorly insulated rooms may require higher-rated heaters or multiple units.

Rooms with high ceilings or large windows lose heat faster, which increases the power consumption of electric heaters. Using thick carpets, curtains, and draft excluders helps retain warmth and makes the heater’s output more effective.

Smart Heaters and Off-Peak Tariffs

Modern smart heaters offer the most efficient way to manage electricity use. These devices can learn your heating habits, adjust automatically, and work in conjunction with smart thermostats to avoid unnecessary usage. Some models also display real-time energy consumption, helping you monitor and manage costs directly.

If you are on an Economy 7 or Economy 10 tariff, you can also take advantage of cheaper off-peak electricity rates. Storage heaters, for instance, use electricity overnight to store heat in thermal bricks and release it gradually during the day. This approach can be far more economical if you can plan your heating around off-peak hours.

Environmental and Energy Efficiency Considerations

Electric heaters are often seen as inefficient from an environmental standpoint when powered by grid electricity generated from fossil fuels. However, as the UK electricity grid continues to incorporate more renewable sources, electric heating is gradually becoming cleaner. When combined with solar PV systems or green electricity tariffs, the carbon footprint of electric heating can be reduced significantly.

It is also worth noting that unlike gas appliances, electric heaters do not produce combustion emissions, making them safer and suitable for homes without proper ventilation. This can be particularly beneficial in flats or older properties where installing flues or ducts is impractical.

Common Questions About Electric Heater Usage

One common question homeowners ask is whether leaving a heater on a low setting all day uses less electricity than turning it on only when needed. The answer depends on insulation and the heater type. Generally, it is more efficient to use the heater only when required, as continuous operation wastes energy. However, for oil-filled or thermostatically controlled heaters, maintaining a steady temperature can be more cost-effective than repeatedly heating a cold room.

Another frequent concern is whether newer models use less electricity. While all electric heaters convert power into heat at the same efficiency, modern designs often feature better controls and insulation that help manage power use more intelligently, resulting in lower running costs overall.

Conclusion

Electric heaters provide quick, clean, and effective heat but can become costly if used as the main source of warmth in a home. The amount of electricity they use depends on the heater’s power rating, how long it runs, and how well your home retains heat. On average, expect a typical 2 kW heater to consume about 2 kWh of electricity per hour, costing around 60 pence on a standard tariff.

By choosing the right type of heater, using smart controls, and improving insulation, you can make electric heating more efficient and affordable. An electrician can assess your property and suggest the most suitable heating options, ensuring both comfort and cost efficiency through the colder seasons.