The Most Powerful 120v Heater To Keep You Warm This Winter

While there are many benefits to using 240 volts over 120 volts, surprisingly, most American households use 120 volts.

If you want to install a space heater and worry about your 120 volts plug, you can still use the most powerful 120v heater.

Of course, I understand that most people believe that 240v is cheaper and more efficient because it uses half the amps that 120v uses. But that’s not true because the cost is almost the same considering that people pay for the wattage used by the device, and not the amp.

The solution is very simple; use whatever you have. If you already have 120V power available, go with that. If you already have 240V power, go with that. The patterns will be the same with either option.

If you still want to go ahead, here are the best 120v heaters that will keep you warm this winter

120V or 240V: Which is Better?

If you are comparing a 240v and 120v device in terms of the cost of electricity, there is no much difference between the two. Your heating costs are in terms of kilowatt per hour.

This is the rate at which the utility company charges for the consumption of every watt of electric power. Therefore, to estimate your heating costs, you need to work with watts and not voltage.

Wattage is the product of voltage and amperage. To determine the wattage capacity of an electric heater, multiply its voltage and the amperage. The amperage reflects the amount of electric current that the heater consumes when it is operating. This, just like the voltage, is indicated on the surface of your heater.

There is no much difference in terms of the wattage of a 120v and a 240v heater because, in general, devices with high voltage tend to consume little amps of electric current. Conversely, devices that have low voltage consume high amps of electric current.

Therefore, your 120v heater will consume a higher amount of electric current than the 240v heater. In the end, the difference between the wattage of the two heaters will be negligible. Therefore, there is no bid difference in the cost of operating a 120v and a 240v electric heater.

How to Size a Garage Heater

Using the right size of a heater will help you keep the heating expenses low and maintain a comfortable environment in your indoor space.

Using a low-capacity heater is inefficient because you will still have to heat the cold spots that will develop in your room. Also, using a heater that has excess capacity is inefficient because you will waste electric power.

Here is a step-by-step process of determining the right size of a garage heater.

  • Determine the area of the garage: The area of your garage or any other space is a product of the length and width. Measure the length and width and multiply the two values to get the real size of the room. If you have a small square-shaped garage with the length and width of 20 feet, then its area will be 400 square feet.
  • Assess the level of insulation of the garage: Determine whether your garage is over insulated or under-insulated. If the garage has excess insulation, then it will require less heating than a properly insulated garage. Less insulated garages will require additional heating to keep the air inside warm.
  • Determine the BTU requirements of your garage: The BTU requirement of the garage will guide you in selecting the most appropriate heater. You can calculate the BTU needs of the garage or any other space by dividing the area by a factor of 200 and then multiplying the answer by 9,000. If the area of your garage is 400 square feet, then the BTU requirement will be 18,000. You can then go for a heater that has to match BTU capacity.

What Type of Heater is Best for the Garage?

There are three primary types of heaters: convection, radiant, and forced air. All these heaters have unique features and modes of operation. You will have to consider your needs, and the nature of the garage before settling on the right type.

Radiant heaters have special reflectors that project infrared radiation to space within the garage. These types of heaters have certain positive attributes, including the ability to provide rapid heating and operating silently. Radiant heaters do not produce noise because they do not have fans. Moreover, they are perfect for zonal heating.

Convection garage heaters use radiators to slowly warm the air and keep the temperatures within the required levels. They contain networks of pipes filled with water or oil. Electric current is converted into heat energy which is transferred to the fluid. The fluid then heats the air in the room over time.

The main drawback of using a convection heater is that you will have to wait for a long time for the temperature in the room to reach the desired level. However, these heaters are very affordable and easy to use. Some of them are mounted on the baseboard or wall while others are used as freestanding space heaters.

Forced-air garage heaters have special fans that are used to push blasts of heated air outside. The heaters use either electricity or natural gas. Some forced-air garage heaters may burn propane to produce the heat. These types of fans are the noisiest because of the inclusion of a fan for forcing the heated air out.

Where should the Heater be Placed in the Garage?

how to size the best 120v heater

It is difficult to keep garages warm because they are exposed to the weather. Normally, garage doors do not seal properly. Therefore, during winter or even at night, cold air currents can freely flow into your garage. Also, hot air currents from outside can flow into your garage when it is hot outside. To deal with this problem, you have to place your heater appropriately.

Positioning Infrared Garage Heaters

If you are using an infrared heater, then ensure that you keep it at a safe distance from the walls. Ideally, the heater should be positioned at least 24 inches from all the vertical walls in the room. This applies when you intend to mount it on the ceiling.

Also, the distance between the ceiling and the heater matters. Ensure that your heater is at least seven feet high from the floor of the house.

Remember to keep the heater away from any combustible materials. A distance of at least 72 inches is usually considered safe enough when using any type of infrared garage heaters.

Positioning Forced Air Heaters

Place your forced-air heater in the coldest corner of your garage. You can determine the coldest corner of the garage by repeatedly measuring the temperature using easily-available thermometers.

If you decide to have the heater mounted on the ceiling, then leave a space that equals the total of the height of the heater and an additional four inches between the top of the heater and the ceiling. Also, ensure that the distance between the bottom of the heater and the floor of the garage is at least six feet.

What is a Good Temperature for a Garage?

Ideally, maintain the temperature of your garage at 45 degrees Fahrenheit. If you live in coastal states, then maintain the temperature of the garage at about 65 degrees Fahrenheit.

These values are ideal because of two reasons. First, it is important to maintain the temperature of the garage high enough to prevent the batteries of the car and any other tool stored in the garage from getting damaged.

Rechargeable lead-acid car batteries should be maintained within a temperature range of negative 4 to 122 degrees Fahrenheit. Extremely low or high temperatures can easily damage the components of the battery, leading to short lifespans. Lithium-Ion car batteries should be kept in areas where the temperature ranges from 32 to 113 degrees Fahrenheit.

Another reason for maintaining the temperature in your garage within the 45- and 65-degrees Fahrenheit ranges relates to the formation of dew. Droplets of water form in air and fall onto surfaces when the air is unable to hold additional moisture. The point at which air is unable to hold additional moisture is referred to as dewpoint.

In coastal zones, the dewpoint ranges from 45 to 65 degrees Fahrenheit. The figures are much lower in inland states: 15 to 40 degrees Fahrenheit.

You have to keep your garage free from the effects of mildew by maintaining the temperature above the dewpoint.

Finally, if you would like to spend some time in your garage, then it will be necessary to maintain a comfortable environment. Keeping the temperature at about 65 degrees Fahrenheit will maintain a cozy environment in the garage.

The Most Powerful 120v Heater

1. Dr. Infrared Portable Space Heater

Dr Infrared Heater Portable Space Heater,...
  • Can heat up a large room with Auto Energy Saving Model With High and Low Feature. Tip-over protection and Overheat protection.Heat Up for a large room - Dual Heating System: Infrared Quartz tube + PTC for 60% more heat than others. Rated around 5200 BTU.
  • Dual Heating Systems featuring infrared quartz tube + PTC with 12-Hour automatic shut-off timer. Amperage: 12.5 Amps
  • IR Remote Control, High Pressure Low Noise Blower with Noise level 39 dB super quiet. Heating can cover for a large room.
  • Electronic Thermostat: range 50 to 85 degrees. Caster Wheels and Lifetime Filter
  • Weights 24 lbs and uses 12.5 Amps of Power. 1500 Watts. Power Cord is 72-inch-long (6 Feet)

One of the features of the Dr. Infrared Portable Space Heater is the dual heating system. It combines an infrared quartz tube with a PTC to ensure effective and rapid heating of small to medium-sized indoor spaces.

It is also safe to use this heater in households that have pets or kids. The heater has all the standard safety features, including tip-over and overheat protection.

When the heater accidentally falls, the tip-over protection feature automatically triggers it to switch off. This prevents the occurrence of fire accidents. The overheat protection also helps to keep the heater safe when the temperature rises above acceptable levels.

You will find it easy to move the Dr. Infrared Portable Space Heater across the house, thanks to the caster wheels. It is easy to roll the heater to any spot and carry out zonal heating.

Sadly, the caster wheels of this heater can easily get damaged. If this happens, then you will have to carry the heater from one room to another.


  • The heater has standard safety features, including tip-over protection and overheating
  • Effective and rapid heating of small to medium-sized spaces because of the dual heating system
  • Great portability because of the caster wheels


  • The blower and red lighting may be unsuitable for bedrooms

2. Cadet RMC151W Register multi-watt 120V wall heater

Cadet Register Series Electric Wall Heater...
  • 500/1000/1500 watt electric wall heater at 120 volts quietly creates heat for small to medium sized rooms
  • Provides maximum warmth with powerful air circulation
  • Creates heat that is great for warming an area up to 200 square feet
  • Blends with any décor for placement in any room
  • Enjoy peace of mind—includes high-temperature safety shutoff feature

The Cadet RMC151W can be a great heating companion in your home, thanks to its excellent heating capacity and aesthetic value. With a small footprint, a glossy white finish, and contemporary design, this heater can be used to enhance the interior décor of your house.

The only notable drawback of using this heater is that it can be quite noisy. Although the powerful inbuilt fan ensures effective and even distribution of heat, it may become quite loud. This is the case when you install the heater in the bedroom.

And if you are keen on ensuring that you get value for your money, then the high durability level of this heater will help you achieve that. Made of commercial-grade steel, this heater remains in perfect condition for many years. This will save you the money that you would otherwise have used on either repairing or replacing your heater.


  • The heater easily blends with any interior décor style because of its modern style, white finish, and small footprint
  • High durability because the heater is made from commercial-grade steel
  • The fan and louvers maximize air supply and overall heating performance


  • The heater is slightly noisy

3. KING PAW1215-W PAW Electric Wall Heater

KING PAW1215-W PAW Pic-A-Watt Electric Wall...
  • Original Pic-A-Watt Element
  • Multiple Wattage Options, to Tailor to a Room’s Specific Heating Requirements
  • Patented Smart Limit Protection
  • Whisper Quiet Squirrel Cage Blower
  • Wall Can w/ QuickSet Stud Tabs
  • Proudly Made in the USA with U.S. & Global Materials
  • 5-Year Limited Warranty

One of the most outstanding features of the KING PAW1215-W is the original Pic-A-Watt technology. You can select the most appropriate heating range for the heater according to the prevailing conditions. This makes it easy to minimize the costs of heating the home as well as maintaining a very comfortable environment.

The heavy-duty blower and vent-style grills maximize the movement of hot air across the room. Because you do not need this heater to be portable, the performance of the fan and louvers are quite useful in creating an evenly-warmed zone in your indoor spaces.

It is easy to get the heater up and running. It comes with all the hardware that you require to get it installed on recessed walls. Besides, one does not need advanced skills to successfully use the one-screw installation method of the heater.

Despite its aesthetic value, great heating capacity and easy of personalization, this heater cannot be relied upon to provide warmth in large indoor spaces. If you have a large living room, then using the KING PAW1215-W may not be enough to maintain a cozy environment.


  • Great convenience of having to pick from different heating ranges
  • Excellent heating performance because of the use of a vent-style grill and heavy-duty blower
  • Easy to install on recessed walls using the one-screw mounting technology


4. Dr. Infrared Heater 1500W Carbon Infrared Heater

Dr Infrared Heater DR-238 Carbon Infrared Outdoor...
  • INDOOR and OUTDOOR HEATER - Heater is IP55 approved for both indoor and outdoor use - perfect for home, backyard, garages, open-air restaurant, outdoor patio or deck. Create a comfortable environment for both your indoor activities and outdoor recreation.
  • CLEAN and INSTANT HEAT - Clean, instant and odorless Infrared heat with 3 power settings, 900W, 1200W, 1500W. 120V, 60Hz.
  • PLUG and GO - uses standard 120V, remote controlled
  • WALL and CEILING MOUNTED - Included wall and Ceiling mounting bracket
  • EFFICIENT - High level Mirror aluminum reflector with 90% reflectivity, and special design to fit the carbon lamp to bring strong heating efficiency.
  • Made with durable and weather proof aluminum

If you are looking for a small but effective heater for keeping your indoor and outdoor spaces warm, then you may consider using the Dr. Infrared carbon infrared heater.

This small but versatile device has been designed to be used in both indoor and outdoor environments. The use of high-quality aluminum steel enables it to overcome the harsh effects of the weather elements.

Whether you would like to have your heater mounted on the wall or the ceiling, the Dr. Heater carbon infrared heater comes with all the hardware that you need. Besides, one does not need to possess technical skills to successfully have this heater up and running. The process is straightforward and simple.

However, like all products, the Dr. Infrared carbon infrared heater is not without flaws. The most notable drawback of using this heater relates to the bright orange color of emitted radiation. The color of the radiation may be quite distracting when the heater is used in bedrooms at night.


  • It provides instant infrared radiation heating
  • Suitable for use in indoor and outdoor spaces
  • It can be mounted either on the wall or the ceiling


  • It may be unsuitable for use in bedrooms due to the bright orange color produced

5. NewAir G73 Hardwired Electric Garage Heater

Newair Electric Garage Heater, Adjustable...
  • [RUGGED EXTERIOR BUILT TO LAST] - The hard-shell exterior is made from heavy-duty material that is built to last, especially in tough climates and work conditions.
  • [SAFETY FEATURES FOR PEACE OF MIND] - This heater is considered one of the safest on the market and is our customers tried-and-true favorite. It is ETL certified for electrical safety, and comes with overheating protection, so rest assured you have one of the most trusted heaters available.
  • [HARDWIRED TO YOUR 30 AMP BREAKER] - The NewAir G73 doesn’t come with any of the maintenance issues of a propane heater. Once your heater is hardwired to your 30-amp breaker, your warm workspace is only a switch away.
  • [AMBIENT HEAT CONTROL WITH ADJUSTABLE LOUVERS] - The 240 Volt heater brings direct heat anywhere in your garage with the adjustable louvers and tilt head. If you happen to be sitting in one location while you work, you can make sure the heat is sent to the exact spot you need. Or you can turn the louvers completely open to allow heat to travel everywhere.
  • [MOUNTING HARDWARE INCLUDED] - Comes with a mounting bracket for you to place it on the wall or ceiling of your workspace. This way you can stay toasty and safe with a heater hidden from busy work areas.

The NewAir G73 is a sturdy heater ideal for heating small to medium-sized outdoor spaces, including garages and workspaces.

Its surface is made of high-quality steel which complements the rugged design to make it an ideal choice for use in tough outdoor environments. The heater can effectively withstand harsh weather conditions and function properly to keep warm spaces that are up to 500 square feet large.

In addition to its rugged design and tough exterior, this heater has a powerful fan that is used to ensure even distribution of the heat. You will not have to mind the loud whirring sound produced by the fan, particularly if you are working in an outdoor environment that is already noisy.

Although this heater comes with a bracket for mounting it either on the wall or roof, it may give you problems during the process. It requires to be hardwired to the 30Amps circuit breaker as part of the installation process.

If you are not a skilled professional, you may consider getting the services of a professional electrician. Nevertheless, this is a small price to pay, considering the excellent heating capacity and lifetime of the heater.


  • ETL-certified for safety
  • Designed to withstand tough environmental and workplace conditions outdoors
  • Great heating capacity with a powerful fan for spreading the heated air evenly


  • Requires a skilled electrician to hardwire it to the circuit breaker during installation

6. Honeywell HZ-789 EnergySmart Electric Oil Filled Radiator

Honeywell HZ-789 EnergySmart Electric Oil Filled...
  • WHOLE ROOM HEAT: EnergySmart technology makes this heater not only powerful but energy efficient. It features Digital EasySet Controls with a 1-12 Hour Timer, adjustable thermostat & 3 heat settings.
  • SAFE & MOBILE: A large, easy-pull handle & easy-glide wheels make this heater simple to move, & it's loaded with safety features: 360° Tip-Over Switch, overheat protection & thermal insulated wiring.
  • INCREASE YOUR COMFORT: Portable heaters can help increase comfort & supplement home heating needs. Honeywell carries a range of heaters including personal, ceramic, fan forced, radiant, & infrared.
  • SMART SAVINGS: Portable heaters are an easy way to add warmth to any space. By turning down your home thermostat a few degrees & heating just the room you're in, a space heater can help you save money.
  • HONEYWELL QUALITY: Help improve heating & energy savings in your home, office, or school using an energy efficient Honeywell portable heater to bring comfort to any sized room from small to large.

A key feature of the Honeywell HZ-789 is its broad range of settings and control features. From an inbuilt digital thermostat and timer to perfectly-positioned physical control knobs, this heater has all the features that you would like to have to adapt its performance to your needs.

Thanks to the thermostat, you can ensure that the heater maintains the temperature of your room within the required range. Besides, one can use the timer to determine the period when the heater functions.

Oil-filled heaters normally pose many dangers whenever they are in use. The situation gets dire if kids and pets are in the home. From hot surfaces to the dangers of fire outbreaks in the case of overheating, these heaters can be quite hazardous if not used carefully.

Luckily, the Honeywell HZ-789 has some of the most advanced safety features, including cool-to-touch surface, tip-over protection, and thermally insulated wiring.

Like all radiation heaters, the Honeywell HZ-789 has an oil-filled radiator which, in turn, transfers heat energy to the surrounding air. Compared to radiant heaters, oil-filled heaters are slower.

When using this heater, you have to wait for several minutes before the temperature of your room rises to the required levels.


  • Easy to personalize using the digital controls and other features, including a timer and thermostat
  • Highly portable because of the four caster wheels
  • Modern design with a sleek black finish offers aesthetic value
  • Has advanced safety features, including thermally-insulated wiring, tip-over protection and overheat protection


  • The heater takes a long time to warm small to mid-sized indoor spaces

Wrap Up

There is really no big difference between using a 120v heater and 240v heater. What matters is going with what you already have, unless you prefer a specific model that uses a different outlet.

There are also different types of heaters and you will almost always find the most powerful 120v heater – you don’t have to upgrade to 240v.

I hope you were able to find the best 120v heater for your space and understand how to size, position, and get the best out of your newly acquired heating unit.

Other Heaters To Consider

Best heater for 500 Square Feet

Best Electric Heater for 800 Square Feet

Best Electric Heater for 400 Square Feet