Electric heaters are a simple and flexible way to warm bedrooms, home offices, living rooms, garages, workshops and commercial spaces. But one of the first questions most people ask before buying one is: how much does an electric heater cost to run?
The answer depends on three main things: the power rating of the heater, how long it runs for and the price you pay for electricity.
A small 1.5kW heater will cost less per hour at full power than a 3kW heater. A 5kW workshop heater will use more electricity than a compact home heater. Larger industrial heaters can use significantly more power, but they are designed for spaces where a small domestic heater would not be suitable.
This guide explains how electric heater running costs work, how to calculate your own cost per hour, and how to choose a heater that suits your room without wasting energy.
You can also browse our portable heating units, compare our 3kW and below portable heaters, or read our heater size and wattage guide.
How Do You Calculate Electric Heater Running Costs?
To calculate how much an electric heater costs to run, you need to know the heater’s power rating and your electricity cost per kWh.
The basic calculation is:
Running cost = heater power in kW x hours used x electricity cost per kWh
For example, if you use a 2kW heater for one hour, it can use up to 2kWh of electricity if running at full power. If your electricity cost was 30p per kWh, that would cost up to 60p for one hour at full output.
The formula is simple, but real world usage can vary. A heater with a thermostat may not run at full power continuously once the room reaches the set temperature. A draughty garage may need the heater to work much harder than a well insulated bedroom.
Electric Heater Running Cost Formula
| Step | What To Check | Example |
|---|---|---|
| 1 | Find the heater power rating | 2kW |
| 2 | Decide how long it will run | 3 hours |
| 3 | Check your electricity price per kWh | 30p per kWh |
| 4 | Multiply kW x hours x electricity price | 2 x 3 x 30p = 180p |
In this example, a 2kW heater running for 3 hours at full power would cost up to £1.80.
Your exact cost will depend on your own electricity tariff, so always check the rate you pay on your energy bill.
How Much Does A 1.5kW Electric Heater Cost To Run?
A 1.5kW electric heater uses up to 1.5kWh of electricity for every hour it runs at full power.
| Electricity Price | Cost Per Hour At Full Power | Cost For 4 Hours |
|---|---|---|
| 25p per kWh | 37.5p | £1.50 |
| 30p per kWh | 45p | £1.80 |
| 35p per kWh | 52.5p | £2.10 |
A 1.5kW heater is usually best for smaller rooms, personal warmth, bedrooms, small offices and occasional top up heating.
For example, the Glaziar 1.5kW Globe Personal Heater is a compact option for targeted warmth in smaller spaces.
How Much Does A 2kW Electric Heater Cost To Run?
A 2kW electric heater uses up to 2kWh of electricity per hour when running at full power.
| Electricity Price | Cost Per Hour At Full Power | Cost For 4 Hours |
|---|---|---|
| 25p per kWh | 50p | £2.00 |
| 30p per kWh | 60p | £2.40 |
| 35p per kWh | 70p | £2.80 |
A 2kW heater is one of the most common sizes for domestic and office use. It can be a good choice for bedrooms, home offices, spare rooms, small lounges and garden rooms, depending on insulation and room size.
Popular options include the Glaziar Portable 2kW PTC Heater in White, the Glaziar Portable 2kW PTC Heater in Black and the Olympus 2.0kW Portable Fan Heater for Garages and Workshops.
How Much Does A 3kW Electric Heater Cost To Run?
A 3kW electric heater uses up to 3kWh of electricity per hour at full power.
| Electricity Price | Cost Per Hour At Full Power | Cost For 4 Hours |
|---|---|---|
| 25p per kWh | 75p | £3.00 |
| 30p per kWh | 90p | £3.60 |
| 35p per kWh | £1.05 | £4.20 |
A 3kW heater can be useful for colder spaces, garages, workshops and rooms that need more power than a compact domestic heater can provide.
The Olympus Pro 3.0kW Workshop Heater and Trotec 3.0kW TDS 20 R Electric Fan Heater are useful options for practical workspaces and unheated indoor environments.
How Much Does A 5kW Electric Heater Cost To Run?
A 5kW electric heater uses up to 5kWh of electricity per hour when running at full output.
| Electricity Price | Cost Per Hour At Full Power | Cost For 4 Hours |
|---|---|---|
| 25p per kWh | £1.25 | £5.00 |
| 30p per kWh | £1.50 | £6.00 |
| 35p per kWh | £1.75 | £7.00 |
A 5kW heater is not usually needed for a normal bedroom or small home office. It is better suited to larger garages, workshops, commercial rooms and spaces that need stronger airflow or faster warm up.
The Trotec 5.0kW TDS 30 R Electric Fan Heater is a higher output option for workshops, construction spaces and unheated indoor environments.
How Much Do Industrial Electric Heaters Cost To Run?
Industrial electric heaters use more electricity because they are designed for much larger spaces. A 9kW heater, 15kW heater or 30kW heater can cost significantly more per hour than a domestic portable heater when running at full output.
| Heater Output | Cost Per Hour At 25p/kWh | Cost Per Hour At 30p/kWh | Cost Per Hour At 35p/kWh |
|---|---|---|---|
| 9kW | £2.25 | £2.70 | £3.15 |
| 15kW | £3.75 | £4.50 | £5.25 |
| 30kW | £7.50 | £9.00 | £10.50 |
These figures are based on full power usage. In practice, the right industrial heater may warm a suitable space faster than an underpowered unit, but it still needs to be matched carefully to the building, power supply and intended use.
For larger spaces, browse our industrial portable heaters, 9kW and above portable heating units and three phase portable heating units.
Electric Heater Running Cost Table
The table below gives a quick comparison of common electric heater sizes.
| Heater Size | Electricity Used Per Hour At Full Power | Cost Per Hour At 30p/kWh | Typical Use |
|---|---|---|---|
| 1.5kW | 1.5kWh | 60p | Small rooms, personal warmth and home offices |
| 2kW | 2kWh | 60p | Bedrooms, offices and small living spaces |
| 3kW | 3kWh | 90p | Garages, workshops and colder rooms |
| 5kW | 5kWh | £1.50 | Larger workshops and commercial spaces |
| 9kW | 9kWh | £2.70 | Industrial spaces and larger work areas |
| 15kW | 15kWh | £4.50 | Large industrial areas |
| 30kW | 30kWh | £9.00 | Very large industrial spaces |
Important: the table uses 30p per kWh as an example only. Your actual cost will depend on your own electricity tariff.
Why A Heater May Not Cost The Full Amount Every Hour
The running cost tables show the maximum cost when a heater runs at full output for the whole hour.
However, many heaters include a thermostat. Once the space reaches the temperature you set, the heater may reduce output or cycle on and off. This means the actual energy use can be lower than the maximum full power calculation.
The amount of time a heater runs at full power depends on:
- Room size
- Insulation
- Draughts
- Starting room temperature
- Target temperature
- Ceiling height
- How often doors are opened
- Whether the heater has thermostat control
- Whether the heater is correctly sized
A well insulated room may warm quickly and hold heat well. A draughty garage or workshop may lose heat quickly, causing the heater to run for longer.
Does A Higher Wattage Heater Always Cost More?
At full output, yes. A higher wattage heater uses more electricity per hour than a lower wattage heater.
However, that does not always mean the smaller heater is the better choice. If a heater is too small for the room, it may run constantly and still fail to make the space comfortable.
For example, a small 1.5kW heater may be fine for a home office, but it may struggle in a cold garage. In that situation, a more suitable workshop heater may be a better choice because it is designed for the environment.
The goal is not to choose the lowest wattage heater. The goal is to choose the right heater for the space.
Is It Cheaper To Use An Electric Heater Or Central Heating?
This depends on the home, heating system, energy prices and how much space you need to heat.
An electric heater can be cost effective if you only need to heat one room for a short period. For example, if you are working in a home office during the day, using a portable heater in that room may avoid heating the whole house.
However, if you are trying to heat several rooms for long periods, multiple electric heaters may become expensive compared with using the main heating system.
A portable electric heater is usually best for:
- Top up warmth
- One room heating
- Occasional use
- Home offices
- Spare rooms
- Garages and workshops
- Temporary heating
For regular whole home heating, a fitted heating system or heat pump may be more suitable.
Are Electric Heaters Energy Efficient?
Electric heaters are efficient at converting the electricity they use into heat at the point of use. The important question is whether the heater is being used in the right place, for the right amount of time and at the right output.
A compact electric heater can be a practical way to warm one room without heating unused spaces. But using a high output heater in a small room, or leaving a heater running when nobody is there, will waste energy.
For the best efficiency, match the heater to the room and use thermostat or timer controls where available.
Electric Heater Vs Heat Pump Running Costs
A standard electric heater creates heat directly from electricity. A heat pump uses electricity to move heat from one place to another.
Because of this, a heat pump system can often provide more heat output per unit of electricity used than a direct electric heater. This is one reason heating and cooling air conditioning systems can be attractive for regular use in homes, offices, garden rooms and commercial spaces.
| Option | Best For | Running Cost Consideration |
|---|---|---|
| Portable electric heater | Quick heat in one room | Simple to use, but cost depends directly on kW rating and usage time |
| Workshop heater | Garages and workspaces | Higher output, suitable for colder practical spaces |
| Industrial heater | Warehouses and large units | Higher hourly cost, but designed for spaces domestic heaters cannot handle |
| Heating and cooling air conditioning system | Regular all season comfort | Can be more efficient for ongoing heating because it uses heat pump technology |
If you only need temporary warmth, a portable heater may be the simplest choice. If you use the space every day and also need cooling in summer, browse our heating and cooling systems.
How To Reduce Electric Heater Running Costs
The easiest way to reduce running costs is to use the right heater in the right way.
Here are practical ways to keep electric heating costs more manageable.
Choose The Right Size Heater
A heater that is too small may run constantly without warming the room properly. A heater that is too large may be unnecessary for the space.
Choose heater output based on room size, insulation, ceiling height and how the room is used. For more help, read our What Size Heater Do I Need? guide.
Use The Thermostat
If your heater has thermostat control, use it. Setting the heater to maximum all the time is usually unnecessary once the room is warm.
A thermostat helps the heater maintain a more comfortable temperature rather than constantly running at full output.
Use A Timer
Timers help stop the heater running longer than needed.
This is useful in home offices, spare rooms, workshops and rooms where you only need heat at certain times of day.
Close Doors
If you are using a portable heater to warm one room, keep the door closed where practical. This helps the room warm faster and reduces heat escaping into areas you are not using.
Reduce Draughts
Draughts make heaters work harder. Check windows, doors, garage doors and gaps where cold air enters the space.
Reducing draughts can make a noticeable difference, especially in garages, workshops and older rooms.
Only Heat The Space You Need
Portable heaters work best when used for targeted heating. They are useful when you want warmth in one room or one work area rather than heating the whole building.
Do Not Block The Heater
Keep air inlets and outlets clear. Blocking airflow can reduce performance and may create a safety risk.
Always follow the manufacturer’s placement instructions.
Maintain The Heater
Keep the heater clean and check it regularly. Dust build up can affect airflow and performance, especially on fan heaters used in workshops or garages.
Best Low Cost Use Cases For Electric Heaters
Electric heaters are most cost effective when they are used for targeted warmth.
Good examples include:
- Heating a home office during working hours
- Warming a bedroom before use
- Adding warmth to a spare room
- Heating a small workshop while working
- Warming a garage for short hobby sessions
- Providing temporary heat where fixed heating is not available
- Using a compact heater instead of heating unused rooms
Electric heaters become less cost effective when they are used to heat large, poorly insulated areas for long periods without proper sizing or control.
Best Electric Heater For Lower Running Costs
The best heater for lower running costs is usually the one that matches the space properly.
For a small home office, a compact 1.5kW or 2kW heater may be more sensible than a larger heater. For a garage or workshop, a small domestic heater may be underpowered, so a rugged 2kW, 3kW or 5kW fan heater may work better.
For larger industrial spaces, high output heaters cost more per hour, but they are designed for areas where smaller heaters would not be effective.
| Space | Running Cost Friendly Starting Point | Suggested Option |
|---|---|---|
| Small office or bedroom | 1.5kW to 2kW | Compact portable heater |
| Home office used daily | 2kW with thermostat | Portable PTC heater |
| Garage | 2kW to 3kW | Workshop fan heater |
| Workshop | 3kW to 5kW | Workshop or commercial fan heater |
| Warehouse | 9kW plus | Industrial heater matched to the space |
| Room used all year | Heating and cooling system | Fitted heat pump air conditioning system |
Recommended Electric Heaters
Here are some useful CoolEasy options depending on the space you need to heat.
Best For Lowest Full Power Use: Glaziar 1.5kW Globe Personal Heater
The Glaziar 1.5kW Globe Personal Heater is a compact choice for personal warmth, small rooms and occasional top up heating.
Because it is a lower output heater, it uses less electricity per hour at full power than larger 2kW, 3kW or 5kW models.
Best For Everyday Small Room Heating: Glaziar Portable 2kW PTC Heater
The Glaziar Portable 2kW PTC Heater in White and Glaziar Portable 2kW PTC Heater in Black are useful options for home offices, bedrooms, spare rooms and small living spaces.
They are a good starting point if you want a compact portable heater for everyday domestic use.
Best For Garages And Hobby Spaces: Olympus 2.0kW Portable Fan Heater
The Olympus 2.0kW Portable Fan Heater for Garages and Workshops is designed for practical spaces such as garages, workshops, small warehouses, trade vans, site work and garden buildings.
It is a better fit than a normal domestic heater where you need a more rugged portable option.
Best For Workshops: Olympus Pro 3.0kW Workshop Heater
The Olympus Pro 3.0kW Workshop Heater is a stronger option for hobby workshops, garages and working spaces that need more output.
It will cost more per hour at full power than a 1.5kW or 2kW heater, but it is designed for spaces where smaller heaters may struggle.
Best For Larger Workspaces: Trotec 3.0kW And 5.0kW Electric Fan Heaters
The Trotec 3.0kW TDS 20 R Electric Fan Heater and Trotec 5.0kW TDS 30 R Electric Fan Heater are suitable for workshops, garages, construction sites and unheated indoor environments.
Choose these where you need stronger airflow and higher output than a small room heater can provide.
Best For Industrial Spaces: Olympus Industrial Heaters
For large commercial and industrial spaces, compare the Olympus 9.0kW Industrial Space Heater, Olympus 15.0kW Industrial Heater and Olympus 30.0kW Industrial Heater.
These are higher running cost products at full output, but they are built for environments where lower powered heaters are not suitable.
Electric Heater Running Cost FAQs
How much does it cost to run an electric heater for one hour?
It depends on the heater size and your electricity tariff. A 2kW heater running for one hour at full power uses up to 2kWh. Multiply 2kWh by your electricity cost per kWh to find the hourly cost.
How much does a 2kW heater cost to run?
A 2kW heater uses up to 2kWh per hour at full output. At 30p per kWh, that would cost up to 60p per hour. Your actual cost depends on your tariff and how the heater is used.
How much does a 3kW heater cost to run?
A 3kW heater uses up to 3kWh per hour at full output. At 30p per kWh, that would cost up to 90p per hour.
How much does a 5kW heater cost to run?
A 5kW heater uses up to 5kWh per hour at full output. At 30p per kWh, that would cost up to £1.50 per hour.
Does a heater use electricity all the time it is switched on?
Some heaters may cycle on and off if they have a thermostat. This means they may not use their full rated power continuously once the room reaches the set temperature.
Is it cheaper to use a smaller heater?
A smaller heater costs less per hour at full power, but it must still be suitable for the room. An underpowered heater may run for longer and still fail to heat the space properly.
Do electric heaters use a lot of electricity?
Electric heaters can use a noticeable amount of electricity, especially higher output models used for long periods. Running cost depends on kW rating, usage time and your electricity price.
Are electric heaters expensive to run overnight?
Running any electric heater for many hours will increase electricity use. If using a heater for longer periods, choose the right size, use thermostat control and follow all safety instructions.
What is the cheapest electric heater to run?
The cheapest heater to run at full power is usually the lowest wattage heater, but it must be powerful enough for the space. For small rooms, a 1.5kW or 2kW heater is often a sensible starting point.
Is a 2kW heater enough for a room?
A 2kW heater can be suitable for many small to medium domestic rooms, depending on insulation, ceiling height and draughts.
Is a fan heater expensive to run?
A fan heater’s running cost depends on its kW rating. A 3kW fan heater costs more per hour at full power than a 2kW heater, but it may be more suitable for workshops and garages.
Are industrial heaters expensive to run?
Industrial heaters have higher running costs because they have higher output. They are designed for large spaces where domestic heaters would not be effective.
Can I reduce the running cost of an electric heater?
Yes. Choose the right heater size, use thermostat control, close doors, reduce draughts, use timers and only heat the space you need.
Should I choose an electric heater or a heat pump?
Choose an electric heater for quick, portable warmth in one room or workspace. Choose a heat pump or heating and cooling system for a more permanent, efficient all season solution.
Final Advice: Running Cost Depends On Wattage, Time And How You Use It
Electric heater running cost is easy to calculate once you know the heater size and your electricity price per kWh.
A 1.5kW heater costs less per hour at full output than a 3kW or 5kW heater, but the right choice depends on the space. A compact heater is ideal for bedrooms and home offices, while garages, workshops and warehouses often need more powerful heating.
To keep costs manageable, choose the correct heater size, use thermostat settings, reduce draughts and avoid heating spaces you are not using.
Explore our portable heating units, compare 3kW and below portable heaters, or speak to the CoolEasy team for help choosing the most suitable heater for your space.