Energy Consumption & The Cost of Running a Space Heater

Heating bills can be one of the biggest expenses for those of use living in colder climates, especially in the winter. With many American families facing difficulties paying for heating costs, finding a more efficient way to stay warm is a priority.

If you’re looking for ways to lower your heating bill, then you may have thought about investing in a space heater to warm just one room within your home. But are space heaters really more effective than central heating — or are you just exchanging heating and gas bills for higher electricity bills?

This post takes a look at the average cost of space heaters and how they can help save you money — if you use them the right way.

What is a space heater? 

Space heaters are small, portable devices designed to warm up specific areas in your home. Think of them as little heat machines you can move around to keep just one room cozy. This is helpful if you don’t want to heat your entire house all the time. For example, you can use a space heater in your bedroom while keeping the rest of the house cooler. 

This not only keeps you comfortable but also helps lower your energy bills. 

What is a kilowatt hour (kWh)?

Before we can determine how much energy an appliance uses, we have to understand watts and kilowatt hours. Watts are the standard measurement rate of energy consumption, with one kilowatt (kW) equalling 1,000 watts.

A kilowatt hour (kWh) is the metric utility companies use to gauge how much electricity your residence uses over time — specifically, the amount of energy used to generate 1,000 watts of power for one hour. Your monthly electricity bill is based on how much your utility provider charges you per kWh. The rate will vary by your location, provider, and season — with certain times of year (such as summer) incurring higher utility rates due to increased demand from more consumers.

For more information about kilowatts and kwH, visit our other blog post “What is a kilowatt-hour and why does it matter?”

How much electricity does a space heater use?

Most space heaters display their wattage rating, which represents the amount of electricity that the heater uses per hour. You can usually find the wattage listed on the product label, on the product packaging, or in the owner’s manual.

A review of different space heaters on Amazon shows that most home space heaters are rated for 1,500 watts on high and 750 watts for the low setting. Even small, portable space heaters are able to offer up to 1,500 watts performance. Larger space heaters will cover more space within a room, which can warm people faster and enable it to run for shorter periods of time.

Determining how many watts, amps and volts a space heater uses

If you don’t have the listed wattage for your space heater, then the simplest way to determine its wattage is to calculate it via the number of volts and amps.

• Volts (V): Short for voltage, volts measure the difference in electric potential between two points in an electrical circuit. This difference is what causes electric charges to flow from an outlet to your appliance. Voltage tells you how much electrical potential the hair dryer needs to operate. Electrical outlets in North America supply 120 volts, which is sufficient for most appliances.
• Amps (A): Short for amperes, amps measure electrical current. The amperage rating tells you the number of electrons flowing through a circuit, which is how much electrical current the appliance draws.

Multiply the voltage by the amperage to determine how many watts your space heater uses; this will also tell you the rate of energy consumption. On average, most space heaters use 12.5 amps when turned on high and connected to a 120-volt outlet.

Let’s use these figures as an example to determine the kWh energy consumption of a space heater:

1. Multiple the voltage by the amperage to get the wattage — 120 volts x 12.5 amps = 1,500 watts.
2. Divide the wattage by 1,000 — which for our example is 1,500 / 1,000 = 1.5 kWh.
3. Multiply that number by the hours of use, which could range from a few hours to the entire day depending on the times of day when you use the space heater. We’re using 12 hours as the maximum number of hours as the Consumer Product Safety Commission recommends that you do not leave space heaters on while asleep.
   • 1.5 kWh x 4 hours = 6 kWh
   • 1.5 kWh x 6 hours = 9 kWh
   • 1.5 kWh x 8 hour = 12 kWh
   • 1.5 kWh x 12 hours = 18 kWh
4. To determine your weekly, monthly, and annual energy use, take your estimated daily kWh usage and multiply it by the number of days you run your space heater per week, per month, and per year. For our calculations, let’s assume the space heater is on 6 hours a day and is in use from November to the end of February.
   • 9 kWh x 7 days = 63 kWh
   • 9 kWh x 30 days = 270 kWh
   • 9 kWh x 120 days = 1,080 kWh

How much does it cost to run a space heater?

Once you know your space heater’s kWH average for a span of time, you’ll need to multiply that value by the kWh usage rate charged by your utility company.

For example, at the U.S. average cost of 16.21 cents per KwH, it would cost an average of $44 a month — so around $175 for the winter months — to run a 1,500 watt space heater for six hours a day.

Of course, you don’t have to run your space heater at max capacity, and running it at lower settings can help you reduce electricity costs. Here is a quick reference guide estimating how much it would cost to operate a space heater at both low and high settings for a set period of time.

For these calculations we’ll assume a “full day” of 12 hours for every day of the week from November through February.

Cost to Run an Average Space Heater

(at U.S. Average of 16.21 cents per kWh)

Cost to Run a Space Heater in Different U.S. States*

And here’s a comparison of electricity costs for different states based on their average kWh charges.

*costs are based on EIA estimation of average kWH as of October 2023.

Does a space heater use a lot of electricity? 

Space heaters use a lot of electricity usually ranging from 500 to 1500 watts. Running one for long periods can lead to a noticeable increase in your electric bill, as they are considered high-energy appliances compared to many others. Here are few reasons why space heaters can significantly increase your electricity bills: 

• Most space heaters operate at 1,500 watts, consuming 1.5 kilowatt-hours (kWh) for every hour of use. At the average U.S. electricity rate of 17.01 cents per kWh, running a space heater for 8 hours daily can add approximately $2.04 per day, or about $61 per month, to your energy costs.     

• Space heaters are designed for small areas. Attempting to heat larger spaces requires the heater to run longer and at higher settings, leading to increased energy usage and higher costs. When used alongside central heating systems, space heaters add to the total energy consumption, further elevating electricity bills. 

• Not all space heaters are equally efficient. Models without energy-saving features, such as thermostats or timers, may operate continuously, consuming more electricity.

Factors affecting the energy usage of your space heater   

Not all space heaters use energy equally. Depending on your model and how long you use it, a space heater can consume different amounts of energy which can result in different billing amounts. Here are some of the biggest factors that affect how much energy your space heater uses: 

1. Heater Efficiency

Space heaters convert electricity into heat, but some energy is often lost as light or motion, reducing overall efficiency. Some thermostats within your space heater are more modern and help maintain a steady temperature by cycling the heater on and off, preventing unnecessary energy use, but their quality can vary. 

Heaters with fans also distribute heat faster and more evenly, reducing runtime and improving energy efficiency.

2. Room Size

Using a heater that’s the right size for the room prevents it from overworking or cycling too often, saving energy. Larger rooms need more energy to heat evenly while smaller rooms might only need a portable space heater to do the trick.

3. Insulation

In the same way, poor insulation lets heat escape, forcing the heater to work harder. When a home is well-insulated, heat remains trapped inside for longer periods, reducing the need for the heater to run continuously. To improve insulation, consider adding weather stripping around doors and windows to seal air leaks.

4. Ceiling Height

In rooms with high ceilings, warm air rises and accumulates near the top, leaving the lower living space cooler. This means the heater has to run longer to maintain warmth at the desired level, increasing energy consumption. 

What are the advantages of space heaters?   

Small space heaters can be a cost-effective option for heating a single room or providing extra warmth to a space with insufficient heating eliminating the need to heat your entire home. 

Unlike central heating systems that can take an hour or more to show results, space heaters provide noticeable warmth within minutes. Lightweight designs and portability allow space heaters to be easily moved between rooms. Some space heaters can even be wall-mounted to save space. 

Certain models double as fans, making them useful in both winter and summer while advanced models offer remote control via smartphones, allowing precise temperature settings, alerts, and better usability. 

What are the disadvantages of space heaters?   

Space heaters are designed for single-room use, so other areas of the house will remain cold unless you use multiple units, which reduces energy efficiency. Some models can be quite noisy, potentially disrupting concentration or relaxation, so checking noise ratings is essential. 

Certain space heaters can become dangerously hot, posing risks to children, pets, and nearby flammable materials. Opt for models with safer surface temperatures. Space heaters also require constant monitoring due to fire risks and can’t be left unattended or placed near carpets, rugs, or flammable items. Safety features like tip-over protection and auto shut-off can provide some reassurance. 

Types of Space Heaters 

Let’s dive in some of the benefits and drawbacks for various types of heaters for your home. 

Electric Space Heaters 

Electric space heaters are ideal for small, enclosed spaces like bedrooms, home offices, or living rooms. They are portable, easy to use, and can be plugged into any standard outlet, making them a versatile choice for supplemental heating. These heaters are perfect when you need quick, focused warmth without heating the entire house. However, they can increase energy bills if used for extended periods, so they are best for short-term or occasional use. 

Gas Space Heaters 

Gas space heaters work well in large, ventilated areas such as living rooms or basements. They are a cost-effective solution for those with access to natural gas, delivering powerful and consistent heat for bigger spaces. While efficient, they require proper ventilation to avoid the buildup of harmful fumes, making them less suitable for smaller or enclosed rooms. These heaters are a great choice for areas where long-lasting warmth is needed. 

Sealed Combustion Heaters 

Sealed combustion heaters are highly efficient and safe, making them an excellent choice for well-insulated homes or large spaces like basements or garages. These heaters pull air for combustion from outside the building, ensuring no indoor air is used or contaminated. This design prevents drafts and reduces the risk of carbon monoxide exposure, making them safer than traditional combustion heaters. 

Fan Heaters 

Fan heaters are compact and lightweight, making them a convenient option for bathrooms, kitchens, or other small rooms that need quick warmth. They use a fan to blow air over a heating element, rapidly warming the space. Their portability makes them easy to move wherever you need heat. However, they can be noisy and are not the most efficient choice for prolonged use or heating larger areas, making them better suited for spot heating. 

Garage Heaters 

Garage heaters are designed specifically for larger, uninsulated spaces like garages or workshops. They come in various types, including electric, propane, and natural gas models, providing powerful heating to combat cold temperatures in these areas. These heaters are a great choice for DIY projects or working in garages during the winter.  

However, they can be energy-intensive, and proper ventilation is essential for non-electric models. Placement should ensure even heat distribution and safe operation, ideally mounted on the wall or ceiling to save space. 

Propane Heaters 

Propane heaters are a powerful and portable heating option, perfect for outdoor spaces like patios, garages, or workshops. They are particularly useful in areas without access to electricity, providing consistent warmth even in off-grid situations. However, these heaters require propane tanks, which need regular refilling, and they produce emissions, so they must only be used in well-ventilated areas. This makes them a great choice for outdoor or semi-outdoor heating needs. 

Electric Wall Heaters 

Electric wall heaters are a space-saving solution for permanent heating in areas like bathrooms, hallways, or entryways. They are mounted directly onto the wall, making them ideal for rooms where floor space is limited. These heaters provide consistent warmth and are an efficient choice for small to medium-sized areas. However, they require installation and are not portable, which makes them less versatile than other options. 

Radiant Heaters 

Radiant heaters are designed to provide direct, targeted warmth to people and objects rather than heating the air. This makes them ideal for living rooms, workspaces, or areas where people remain stationary. They are highly energy-efficient and excellent for quick heating, but they may not evenly warm an entire room. Radiant heaters are best used for focused comfort in smaller or specific areas. 

Infrared/Reflective Heaters 

Infrared heaters work by emitting electromagnetic waves that warm people and objects directly, similar to the way sunlight feels. They are quiet, energy-efficient, and great for spot heating in dining rooms, bedrooms, or cozy corners like reading nooks. While they provide immediate warmth, they are less effective for heating large, open spaces since they don’t heat the surrounding air. These heaters are ideal for localized warmth in specific areas of your home. 

Ceramic Heaters 

Ceramic heaters are a popular choice for bedrooms, living rooms, or home offices due to their efficient and quick heating capabilities. They use ceramic plates to generate heat and often include built-in safety features like overheat protection. These heaters are portable, easy to use, and provide consistent warmth in small to medium-sized rooms. However, they may not be powerful enough for heating larger spaces, making them best suited for focused use. 

Kerosene Heaters 

Kerosene heaters are a powerful heating solution for garages, workshops, or emergency situations in off-grid areas. They produce strong, consistent warmth and are a reliable option when electricity isn’t available. However, they require kerosene fuel, which can be messy to handle, and produce fumes that necessitate proper ventilation. Kerosene heaters are best for outdoor or semi-outdoor use where robust, portable heating is needed. 

Which space heater is safest? 

According to U.S. Department of Energy, Sealed Combustion Heaters are safer and more efficient than many other types of space heaters. Unlike traditional heaters, they don’t use the warm air from inside the room for combustion, which means they don’t waste heated air by sending it outside. This design helps keep the room warmer and uses energy more effectively.  

Additionally, sealed combustion heaters are less likely to create backdrafts, which can pull harmful gases like carbon monoxide into your living space. This makes them a better option for maintaining good indoor air quality and ensuring safe operation. 

What is the best space heater for a large room? 

The best space heaters for large rooms depend on the layout of the space. Infrared heaters are a great option because they heat up large, open spaces quickly by warming the objects and people directly in their path. These heaters work well in areas like garages or open rooms and can be mounted on a wall or hung from the ceiling. However, they only heat what they can “see,” so they might not work well in rooms with lots of furniture or walls blocking the heat. 

If your room has furniture or walls dividing the space, an electric or ceramic heater with a fan is a better choice. The fan helps move warm air around, spreading heat evenly across the entire room. This makes them more effective in rooms with multiple compartments or obstacles. 

Is a space heater more or less expensive than turning the heat on?

During the winter months, is it cheaper to turn up the thermostat or use a space heater? The answer really depends on your local electricity rates compared to your heating rates. Heating bills will vary depending on your local rates of gas or electricity, the temperature you set your thermostat to, and how large your home is.

Estimates for an average monthly heating bill throughout the contiguous U.S. states can range from as low as $30 a month in some southern states to as high as $168 a month in the Midwest. In states with higher estimated monthly average heating bills — such as Illinois ($168), Michigan ($106), or Ohio ($106) — it would be less expensive to run a 1,500 watt space heater for a full 12 hours every day of the week.

Of course, the actual costs will depend on how you’re using your space heater. Smaller spaces, such as single family homes or apartments, may not need to run a space heater on high for the entire day. If you can achieve a comfortable temperature in a room by running on the low setting for a few hours a day, then a space heater will save you even more money.

The larger your home, the more it costs to use central heat and the greater your savings will be if you employ a space heater to warm a single room. However, compared to central heat, space heaters are not as efficient for an entire house. While one space heater is less expensive than central heating, running multiple space heaters could dramatically increase your electricity bill.

For example, running three space heaters on low for 12 hours will cost you around $131.40 a month at the average U.S. kWH rate. Running all three space heaters on high would add up to around $262.80 — much more expensive than even the highest average heating bill.

Is it dangerous to heat a home using a space heater?

While space heaters are convenient and can save you money, they can also be dangerous if used incorrectly. Heating equipment, including space heaters, is a leading cause of fires in U.S. homes, accounting for 13% of all house fires between 2016 and 2020.

If you’re going to purchase or already own a space heater, be sure to check for a label from a recognized testing facility — such as UL Solutions or ETL (Intertek) — that verifies the space heater meets recommended U.S. safety standards.

To keep you and your family safe, be sure to follow these other tips from energy.gov and Consumer Reports when using a space heater:

• Turn off the space heater after using it, when going to bed, or leaving the house. Many space heaters now have an automatic shut-off function for certain or after a set amount of time that helps reduce your risk.
• Place the heater on a hard, level surface away from foot traffic. Don’t place it on carpet or on tables. Give it the right amount of space and be sure to keep it safely away from children and pets.
• Plug the space heater directly into a wall outlet if possible. If you do need to use an extension cord, prioritize a heavy-duty cord rated for drawing 10 to 15 amps of power.
• Be sure to always follow general electrical safety practices when using any electrical appliances or outlets.

Can a space heater cause carbon monoxide poisoning? 

Carbon monoxide (CO) is a gas that you can’t see, smell, or taste. It is created when carbon doesn’t burn completely during combustion.  Most cases of carbon monoxide (CO) poisoning happen during the winter in colder regions. One common cause is unvented space heaters used inside homes. These heaters burn fuel, like kerosene or natural gas, and use the air in the room for the heating process. 

 Instead of venting harmful gases like CO outside, they release them into the room, which can be dangerous. If the heater is not installed properly or is malfunctioning, it can also reduce the oxygen in the room and fill the space with toxic fumes. 

Newer unvented space heaters are safer because they have oxygen sensors that automatically turn off the heater if oxygen levels drop too low. However, older models lack this safety feature, making them riskier to use. Due to these safety concerns, some states have banned unvented space heaters altogether. 

What are the symptoms of carbon monoxide poisoning? 

• Headache: A dull, persistent headache is often the first sign of CO exposure. 

• Dizziness: Feeling lightheaded or unsteady, making it hard to maintain balance. 

• Weakness: A general sense of fatigue or inability to perform physical tasks. 

• Nausea and Vomiting: A sick feeling in the stomach, often mistaken for food poisoning. 

• Shortness of Breath: Difficulty breathing or feeling like you can’t get enough air. 

• Blurry Vision: Vision becomes unclear or unfocused, making it hard to see clearly. 

• Disorientation: Feeling confused, dazed, or having trouble thinking clearly. 

• Loss of Consciousness or Coma: Fainting or slipping into an unconscious state. 

• Death: Prolonged exposure to CO can result in fatal outcomes. 

Can you leave a space heater on all night? 

It’s not recommended to leave a space heater on all night. Doing so increases the risk of fire hazards. While modern space heaters often include safety features like tip-over protection and auto shut-off, it’s generally not recommended to run them unattended overnight. Here’s why: 

1. Even with built-in safety features, space heaters can overheat, malfunction, or ignite flammable materials nearby, such as curtains, bedding, or furniture. According to the National Fire Protection Association (NFPA), space heaters are responsible for more than one-quarter (29%) of home heating fires. 
2. Fuel-burning space heaters, such as kerosene or propane models, can emit carbon monoxide if not properly ventilated, leading to potentially fatal poisoning. 
3. In poorly ventilated rooms, unvented space heaters can deplete oxygen levels, which may cause respiratory issues or even suffocation. 
4. Prolonged operation may cause the heater’s internal components to overheat, even if the exterior feels cool to the touch, increasing the likelihood of failure. 

If you left it on all night, for example, from 10 PM to 6 AM, that’s 8 hours. At the average U.S. electricity rate of 17.01 cents per kWh, running a space heater for 8 hours daily can add approximately $2.04 per day, or about $61 per month, to your energy costs. 

Why does my space heater keep turning off? 

If your space heater keeps turning off, there are a few reasons this might be happening: 

Power Supply Issues 

If your heater keeps turning off, this could be an indication that your heater may not be receiving power due to a disconnected plug, a tripped circuit breaker, or a blown fuse.  

To troubleshoot this problem, try checking if the circuit breaker is tripped or a fuse has blown; reset the breaker or replace the fuse if needed. 

Overheating Protection 

Dust or debris blocking air filters and vents, restricting airflow and causing overheating. When this happens most space heaters are programmed to turn off to avoid the risk of a fire hazard. 

Faulty Power Supply 

If your space heater is on the older side, loose or damaged power cords, faulty outlets, or inadequate power supply could cause your heater to keep turning off. To troubleshoot this problem, try inspecting the power cord for visible damage. Try plugging the heater into a different outlet to rule out outlet issues. 

Overloaded Circuit 

If your space heater is plugged into an outlet along with multiple high-wattage appliances on the same circuit, this can cause the breaker to trip thus shutting off your outlet. To solve this problem, try unplugging other appliances on the same circuit and reset the circuit breaker that’s tripped. 

Internal Component Failure 

A malfunctioning thermostat, heating element, or other internal parts can cause your space heater to frequently turn off. This is especially true with older models and those that are used repeatedly. If you suspect this issue, check for any unusual sounds or smells when the heater is on, as these may indicate internal damage. 

If the problem persists, consult a professional technician or consider replacing the heater. 

FAQs

Do portable heaters use a lot of electricity?

At an average of 1,500 watts for the high setting, space heaters use a high amount of electricity compared to other appliances. Even full-sized refrigerators only average around 800 watts. While some smaller appliances such as hair dryers can draw even larger quantities of electricity, they’re used for a much shorter amount of time.

Are all electric space heaters 1,500 watts?

On average, most commercial space heaters will have a maximum high setting of 1,500 watts and a lower setting of 750 watts.

How big of a room can a 1,500 watt space heater heat?

Assuming 8-foot ceilings and good insulation, it takes roughly 10 watts of heating power for every square foot of floor area in a room. So, the average 1,500-watt heater should be able to heat a 150 square foot room. However, that equation changes a bit due to other variables, such as higher ceilings, lack of insulation, number of windows, and average outside temperature.

Do portable heaters run up your electric bill?

A single portable heater won’t use an excessive amount of electricity provided that it’s not running 24/7. However, if you run multiple space heaters at the same time in different rooms, you could spend more on electricity than you’re saving on heating.

Does a portable heater save money?

It can be cheaper to use a portable heater, rather than central heating, to warm up a single room.

What’s the best time to run a space heater?   

The optimal time to use a space heater is when you’re present in the room and need additional warmth. It’s important to turn off the heater when you leave the room or go to sleep to ensure safety. 

What size battery do you need to back up a space heater?  

Space heaters typically require a significant amount of power, often around 1,500 watts. Using a battery backup would necessitate a high-capacity battery, which may not be practical for most users. It’s generally more efficient to use space heaters with a standard electrical outlet.  

Can you plug a space heater into a surge protector? 

No, you should not plug a space heater into a surge protector, power strip, or extension cord, as this can cause overheating and potentially lead to a fire. Always plug space heaters directly into a wall outlet. 

How can I save electricity with my space heater?

Smart and careful usage of a portable space heater will help save you money, but excessive use can run up your electricity bill. Here’s what you need to know to save on electricity when using a space heater.

• Determine when to use your central heating vs. an electric space heater. If everyone is gathered together in one room, then using a single space heater makes sense rather than heating up the entire house. However, if you have people in multiple rooms, it’s more efficient to heat the house rather than run many different space heaters at the same time.
• Use a timer or settings to automatically set your space heater. The longer a space heater runs, the more electricity it consumes. Modern space heaters will have automatic settings to turn off after a set amount of time or when the area reaches a specified temperature. Using these automatic presets can ensure you’re not wasting electricity.
• Cover up while indoors during the winter months. The best way to stay warm during the winter months is to dress warm. Wear extra layers of clothing, socks, and slippers to keep warm as you move through the house. That way, you don’t need to set your space heater or your central heating too high.
• Take the right steps to better conserve heat in your home. Besides dressing warmly, there are other ways to winterize your house to conserve heat. Purchasing smart thermostats, buying heavy curtains, covering air leaks, and updating your insulation are the most efficient ways to save money on heating.
• Select an energy plan that fits with your lifestyle. If you want more control over your energy bill and don’t want to worry about spikes in your kWh charges, see if your retail energy provider offers Unlimited Energy or Fixed-Rate plans.Fixed-rate plans guarantee a cost that does not change for a specified period of time, while unlimited energy plans allow you to pay the same amount every month without worrying about fluctuating energy costs.*You can even choose Earth-Friendly Energy plans if you want to power appliances with renewable electricity plans or heat your home with carbon-neutral gas plans.

* Restrictions apply. Enrollment based upon program eligibility. Customers using more than 125% of normal monthly usage as determined by Santanna may be required to switch plans.