Informational Guide

How Much Electricity Do Space Heaters Use?

Space heaters are known for efficiency and providing quick heat. Learn about their running costs and electrical usage with our guide.

by Josh M

Space heaters are a really effective way to heat an area but are they the most efficient? It pays to understand just how much it costs to run different electricals in your home so you can consider the best option for you.

Many factors influence energy consumption, and in this guide, we’ll help explain how much electricity a space heater uses and how much you should expect it to cost you.

3 Samples of Space Heater

Your space heater won’t always use a set amount of electricity, and there are a variety of factors that influence usage. It’s important to understand these so you know why your bills might vary slightly from month to month.

It’s also important to remember that not all space heaters have a thermostat which means it can’t just automatically adjust to changing conditions. Here’s a quick breakdown of the most important factors to be aware of:

Air Temperature Outside

The colder it is outside, the more likely it is to be colder inside. This means your space heater will need to work harder to warm up the area, leading to higher energy consumption.

Quality Of Your Home Insulation

The quality of your insulation impacts how much heat is leaving your home. If you have poor insulation, your space heater will need to work harder and use more electricity to heat the space. It can be worth considering investing in better insulation, double glazing, and draft excluders to keep costs down.

Room Dimensions

The bigger the room, the harder it will be to heat. In a larger room, you’ll need to run the space heater for longer to impact the overall temperature, so it’s important to buy a space heater that is appropriate for the size of the room.

The Condition of The Heater

Older or worn-out space heaters can often have components inside which are no longer operating optimally. When this happens, it can mean your device is compensating by working harder and drawing more electricity to function. This can lead to a noticeable rise in your energy bills each month.

See our favorite space heaters here

On & Off-Peak Electricity Rates

Electricity rates aren’t always set, and there are certain peak times where you’re charged an excess to use your electricals. These are peak times, and they vary slightly depending on your energy provider. Typically, peak electricity rates are during the day and off-peak times are at night. It will generally cost more in the late afternoon and first thing in the morning when more homes are drawing electricity.

When considering the overall cost of powering your space heater, you should look at your electricity provider’s peak times and avoid them. You will generally pay between 5 and 10% more per unit during peak hours, so it’s worth avoiding them.

Electricity Consumption of a Space Heater

The amount of electricity your space heater uses is measures in watts (W). The higher the watts, the more powerful the space heater is, and generally, that makes them better suited for larger spaces. You should be able to find the wattage of the space heater on the packaging or in the specifications.

As a general rule, 10 watts of electricity will be needed to heat 1 square foot, so it’s important to know the dimensions of your room before selecting your heater. For example, 500 watts will work in a room up to 50 square feet, 1000 watts will work in a room up to 100 square feet, and 1500 watts will work in a room up to 150 square feet.

Some space heaters come with two settings so you can crank up the heat if you need to. Generally, this is only for models with 500, 1000, or 1500 watts, but it’s worth noting because obviously, the electricity consumption will go up if you change settings.

To work out the cost of running a space heater, you need first to work out how many kilowatts per hour are being used (kWh). To determine this, you divide the number of watts by 1000. So, if you had a 1000-watt space heater, it would be 1kWh to run.

The average price per kWh across the US is 13.9 cents. Therefore, the equation to work out the cost per hour is:

kWh used x $0.139 = Cost per hour

For this example, we’ll say it’s a 1000 watt space heater.

1 x 0.139 = $0.139 to run per hour.

To determine the cost per day, you just have to multiply this figure by the number of hours it will run for each day. For this example, we’ll say it’s running for 5 hours a day.

kWh used x 0.139 x hours run a day = Cost per day

1 x 0.139 x 5 = $0.695

To then work out the cost per month, you multiply this by 30.

kWh used x 0.139 x hours run a day x 30 = Cost per month

1 x 0.139 x 5 x 30 = $20.85

Room Size (Max Sq Ft) Required Wattage Running Hours per Day Cost per
Cost Per Day Cost for 30 days
20 200 Watts 5 $0.0278 $0.14 $4.17
50 500 Watts 5 $0.0695 $0.35 $10.50
70 700 Watts 5 $0.0973 $0.49 $14.7
100 1000 Watts 5 $0.139 $0.70 $21
150 1500 watts 5 $0.2085 $1.04 $31.20

*All guides in the table are approximates and will also be determined by more factors.

Calculating the Cost to Run a Space Heater

The table below shows the average cost of running a space heater, but electricity rates can vary, so you may want to do it yourself. You should be able to find the rate you’re paying on your electricity bills and then plug it into the following equation:

Wattage/1000 = kilowatts per hour (kWh)

kWh x cost per kWh = cost per hour

We’ve given a breakdown below for the hourly cost at different electricity rates so you can see how much it changes as you up the wattage.

Required Wattage @5 Cents @10 Cents @15 Cents @20 Cents @30 Cents
200 Watts 1 2 3 4 6
500 Watts 2.5 5 7.5 10 15
700 Watts 3.5 7 10.5 14 21
1000 Watts 5 10 15 20 30
1500 watts 7.5 15 22.5 30 45

How To Use The Space Heaters Efficiently
(Saving Money Tips)

Hopefully, you now have a better idea of how much it costs to run a space heater, but there are things you can do as an owner to help use the machine more efficiently. This will not only lower your bills but will help you protect the longevity of the machine, so you save money by not having to replace the heater as frequently.


Your heater is working to raise the air temperature in a room, but if the space is poorly insulated, then your machine will be putting in more effort than it needs to. This means it needs to run for longer and burns more electricity. You should consider investing in extra layers of insulation and double glazing to keep the heat in. You can even just close doors, windows, and curtains to help keep the room warmer for longer.

Get A Thermostat

Space heaters can be fitted with a thermostat that allows you to control the temperature of the room. You can set this to the lowest setting you’re happy with to make sure you aren’t wasting electricity or energy where it’s not needed.

OnSystems Thermostat
Install A Timer

You can install a timer on your space heater, so it only runs for a fixed period of time. This helps you control and limit the electricity consumption and stay on top of how much you’re spending.

Get The Right Size

Make sure you measure the room before you purchase so you ensure you have a space heater that’s suitable for the space. If your space heater is too small, it will have to work harder to try and heat the space, which can push your bills up.

If your space heater is too big, it’ll be doing more work than it needs to and using electricity at a higher rate. Getting the right size is the best way to improve the efficiency of the heater.

Maintain The Unit

A faulty or worn-out space heater can stop the overall effectiveness of the unit. Ensure you clean the heater regularly to remove any dirt, debris or blockages and open up the heater every few months to check if any parts need to be replaced. This will keep it running correctly and stop it from drawing more electricity than it should.

People Also Ask (FAQ)

What should my space heater be set at?

Space heaters often only have 1 or 2 settings. You should start on the lowest setting and only increase it if you need the extra heat. If set on a thermostat, then you should aim for between 70- and 78-degrees Fahrenheit.

How long can I leave the space heater on?

Space heaters are designed so they can be left on forever, but this is a really inefficient way to use the heater. You are best off using it for intense bursts over a few hours each day to heat the space and save money on electricity.

Can I leave my space heater on overnight?

While most modern space heaters have safety features built-in, we do not recommend leaving your space heater on overnight.

Do space heaters automatically shut off?

No, a standard space heater won’t shut off automatically. If the heater has a built-in thermostat or is wired up to one, then it will shut off once the desired temperature is reached. However, some heaters have a safety feature that will shut them off if they overheat.

Space Heater Safety Tips


Space heaters are an effective way to heat a room, but they can be costly. Hopefully, this article has helped you understand how much they cost, how to work out your own specific costs, and what you can do to make them as efficient as possible.

Josh M

My name is Josh and I am obsessed with the HVAC industry. I created this website to help HVAC techs of all levels get the best out of their heating & cooling systems. I have spent thousands of hours studying air conditioners, heaters and home air products so you can learn & buy with confidence. Learn more about the team here.