Heater running cost UK calculations help you estimate how much different electric heaters cost to run. This guide explains how to calculate electricity costs using heater wattage, running time and your electricity tariff, together with the factors that affect real-world heating costs in British homes.
Quick answer: to estimate the cost of running a heater, multiply the heater power in kilowatts by the number of hours used, then multiply that by your electricity unit rate. These examples use 30p per kWh as an easy illustration, but your actual rate may be different. Check your own tariff and current Ofgem guidance before relying on any figure.
The cost depends on the heater’s wattage and how long it is actually drawing power. As a simple example, a 2kW electric heater running continuously for one hour at 30p per kWh would cost around 60p.
In practice, many heaters do not run at full output every minute once the room reaches temperature. A thermostat, timer or heat setting can reduce actual electricity use, while a cold or poorly insulated room can make the heater work harder for longer.
How to Calculate Heater Running Cost UK
Use this simple formula:
Heater power in kW × hours used × electricity rate per kWh = estimated running cost
For example, a 1.5kW heater used for 3 hours at 30p per kWh would be:
1.5 × 3 × £0.30 = £1.35
This is only an estimate. Your final cost depends on your electricity tariff, whether the heater cycles on and off, and how much heat the room loses while the heater is running.
This heater running cost UK guide uses practical examples to help you compare different heater sizes and understand how electricity costs can vary between households.
Average running cost by heater type
Different electric heaters often have similar running costs when they use the same wattage. The main difference is usually how they deliver heat and how long they need to stay on.
| Heater type | Typical power | Estimated cost per hour at 30p/kWh | Best used for |
|---|---|---|---|
| Fan heater | 2kW | About 60p | Quick short bursts of heat |
| Convector heater | 2kW | About 60p | Heating a small to medium room |
| Oil-filled radiator | 1.5kW | About 45p | Slower, steadier room heating |
| Panel heater | 1kW | About 30p | Background heat in a small space |
| Infrared heater | 0.7kW | About 21p | Direct heat for a person or small zone |
A lower-wattage heater is not automatically better if it needs to run for much longer. The practical cost depends on how quickly it warms the space and whether the room can hold that heat.
If you are comparing heater types specifically, read our guide to the cheapest electric heater to run in the UK.
Running cost by heater wattage
Wattage gives you the clearest starting point. The higher the kW rating, the more electricity the heater can use per hour when running at full power.
| Heater power | Electricity used in 1 hour | Estimated cost at 30p/kWh |
|---|---|---|
| 500W | 0.5kWh | 15p |
| 750W | 0.75kWh | 22.5p |
| 1kW | 1kWh | 30p |
| 1.5kW | 1.5kWh | 45p |
| 2kW | 2kWh | 60p |
| 2.5kW | 2.5kWh | 75p |
These figures assume the heater runs continuously at full output. A heater with a working thermostat may use less once the room reaches the set temperature.
A heater running cost UK calculation should always be treated as an estimate because thermostat cycling, insulation and your electricity tariff all influence the final cost.
Running cost by hours used
The number of hours used often matters more than small differences between heater types. A modest heater used all evening can cost more than a powerful heater used briefly.
| Example use | 1kW heater | 1.5kW heater | 2kW heater |
|---|---|---|---|
| 1 hour | 30p | 45p | 60p |
| 2 hours | 60p | 90p | £1.20 |
| 3 hours | 90p | £1.35 | £1.80 |
| 5 hours | £1.50 | £2.25 | £3.00 |
For a home office, evening living room or bedroom, the most useful calculation is usually your real daily use rather than the maximum hourly cost printed on the heater label.
What affects your real heater running cost?
- Your electricity tariff: unit rates vary by supplier, payment method, region and tariff type.
- Heater wattage: a higher kW rating can use more electricity when running at full power.
- Thermostat behaviour: thermostats can cycle the heater on and off once the room reaches temperature.
- Room size: larger rooms usually need more heat and longer running times.
- Heat loss: draughts, poor insulation and exposed walls can make a heater run for longer.
- Usage pattern: short targeted use is very different from leaving a heater on for several hours.
Energy Saving Trust notes that heating controls can help reduce wasted energy, while reducing heat loss can help a home stay warmer for longer.
How to reduce heater running costs
The cheapest approach is not always buying a different heater. Often, it is about using the heater for less time, using the thermostat properly, and keeping heat in the room for longer.
- Use a timer rather than leaving the heater on without a clear end point.
- Close internal doors when heating one room.
- Reduce draughts around doors, windows and unused chimneys.
- Use thermostatic controls where available.
- Heat the room you are using, not the whole home, when appropriate.
- Check whether central heating controls or TRVs would be more efficient for your situation.
For a more practical room-by-room approach, see our guide to the cheapest way to heat a room in the UK.
Electric heater vs central heating: which costs less?
An electric heater can be practical if you only need to heat one room for a short period. Central heating may be more suitable when several rooms need heating or when the whole home needs to stay at a steady temperature.
The right answer depends on the number of rooms, your heating system, your tariff, insulation, and how long you need heat. A portable electric heater is not automatically cheaper just because it heats a smaller area.
Frequently asked questions
How much does a 2kW heater cost to run per hour?
At an example electricity rate of 30p per kWh, a 2kW heater running continuously for one hour would cost about 60p. Your actual cost may differ depending on your tariff and whether the heater cycles on and off.
Is a 1kW heater cheaper to run than a 2kW heater?
Per hour at full power, yes. A 1kW heater uses half the electricity of a 2kW heater. However, if it takes much longer to warm the room, the practical difference may be smaller.
Do oil-filled radiators cost less to run?
Oil-filled radiators are not automatically cheaper per unit of electricity. Their advantage is that they provide steadier heat and may cycle on and off once warm, depending on the thermostat and room conditions.
Does a thermostat reduce heater running cost?
A thermostat can reduce wasted electricity by switching the heater down or off once the target temperature is reached. The saving depends on the room, insulation and how the heater is used.
Should I use an electric heater or central heating?
For one room and short periods, an electric heater can be practical. For several rooms or long heating periods, central heating with suitable controls may be more appropriate.
Bottom line
The easiest way to estimate heater running cost in the UK is to multiply the heater’s kW rating by the hours used and your electricity unit rate. The number is useful, but it is only the starting point.
Our heater running cost UK examples are designed to help you estimate everyday heating costs rather than predict the exact amount that will appear on your electricity bill.
For real homes, the final cost also depends on heating controls, how quickly the room loses heat, and whether the heater is used for short targeted warmth or long continuous heating.