2020 Buyer's Guide

Smallest Window Air Conditioner Units For Cooling Homes

The smallest window air conditioner units on the market are more efficient than portable ACs. If you choose a smaller AC unit that properly fits your room, you’ll keep your space even cooler. Here’s how to do it.

2020 Buyer's Guide

Smallest Window Air Conditioner Units For Cooling Homes

The smallest window air conditioner units on the market are more efficient than portable ACs. If you choose a smaller AC unit that properly fits your room, you’ll keep your space even cooler. Here’s how to do it.

by jtanner

Lightweight Model

hOmeLabs Window Air Conditioner – 5000 BTU AC Unit With 7 Temperature Settings And 2 Fan Speeds

This 36 lb. portable air conditioner offers 5000 BTU of comfort and is excellent for cooling spaces up to 150 sq.ft.

Our # Choice

Frigidaire FFRA0511R1
Frigidaire FFRA0511R1

This 41 lb. portable air conditioner offers 5000 BTU of comfort and is excellent for cooling spaces up to 150 sq.ft.

Energy Efficient


This 45 lb. portable air conditioner offers 5500 BTU of comfort and is excellent for cooling spaces up to 200 sq.ft.

Window air conditioners are generally more efficient than their portable AC counterparts, but you can further improve the cooling power of your unit by getting something that matches your space. And sometimes that means going smaller, not larger.

Each summer, thousands of portable and window air conditioner units are sold during hot and sweltering summers. Though many consumers wait until it’s too late to get help with their cooling, informed buyers can wade through the science of air conditioners to find a unit that fits their space best.

Case in point? Larger ACs aren’t always better, and in fact, the US Department of Energy recommends AC units that are appropriate to the size of the space being cooled. “A small unit running for an extended period operates more efficiently and is more effective at dehumidifying than a large unit that cycles on and off too frequently,” says the US Department of Energy’s guide on room air conditioners.

They note that larger units can “perform less efficiently and less effectively than a smaller, properly sized unit” because the room will be cooled before it can be properly dehumidified, or have the moisture removed from the air. As a result, the air can feel humid and less than desirable, whereas a smaller unit will cool and dehumidify space at an appropriate rate, leaving you with cooler, comfortable air and circulation.

All that is to say: bigger isn’t always better. So when you’re looking for a window AC unit, consider that smaller units are often more effective – if you’re looking to cool a small amount of space (if you’re cooling a larger space, we also recommend a unit that’s small but still powerful – read below).

Window Size (Width & Height)

The type of air conditioner that is feasible for your household is dependent on various factors, but none more important than the size of your window. Previously constructed houses usually feature smaller windows where standard air conditioners just won’t fit.

The size of your window is also dependent upon the size of your room. If your room has a tiny window that cannot contain a standard air conditioner, you should look towards an air conditioner for a small window opening as they emerge as the only option in such situations.

Windows that measure less than 25 inches in width and are unable to open higher than 15 inches high are perfect for thin window air conditioners, eliminating the need to undertake any modification or renovation.

Power (BTUs)

Small air conditioners consume lesser power units than their larger counterparts, and this has profound implications. Air conditioner power is measured in British Thermal Units (BTUs), which is a measurement of how much heat energy is being moved around.

Just to give you an idea, a match when lighted has a 1 BTU rating. Majority of the air conditioners that fit narrow windows fall between the 4000-6000 BTU ratings – enough to cool spaces as big as 400 square-feet.

The efficiency at which larger units cool considerable spaces is unprecedented, and it comes with the added advantage of paying a relatively smaller sum upfront.

Energy Efficiency (EER)

While installing air conditioners, one of the frequently asked questions is: “how will it affect my electricity bills?”

This is where EER, short for Energy Efficiency Ratio, provides a satisfactory answer. EER is the rating given to air conditioners pertaining to the amount of power they consume. It is calculated by dividing the cooling capacity (BTUs) by the power input (Watts) – the higher, the better.

The EER has a significant impact on the power bill that you receive. The higher the efficiency, the more it saves in electricity costs by using fewer watts – without hindering the cooling performance of your small air conditioner.

How We Found the Best Small Window AC Units

To help you come across the best compact window air conditioner that fits perfectly in your window, we invested considerable hours in mapping out the specifications and performance statistics of more than 30 models – ranging from Frigidaire to General Electric.

Throughout our research, analysis shows that the average small window air conditioner measures 15.5 inches in height and 15 inches in width. The average weight among the models that we measured came up to around 46.6 pounds, indicating the air conditioners’ light-weightiness.

After thorough testing, ultimately we chose the best six small window air conditioners that stood out due to various factors, such as their remarkable energy efficiency, cooling performance, and excellent consumer experiences. We also considered lightweight air conditioners as part of our process.

In addition to Frigidaire’s two mini window air conditioners, our list also includes one from hOmeLabs, General Electric (GE), Keystone and Haier.

6 Best Small Window Air Conditioners Reviewed

Frigidaire FFRA0511R1

Editor’s #1 Choice

BTUs 5000
Dimensions 15 x 16 x 12 “
Weight 41 lbs
Cooling Area Up to 150 sq. ft.
EER 11.1
Estimated Yearly Energy Cost $41

The editor’s choice on our list, the Frigidaire FFRA0511R1 5,000 BTU-unit cools quickly and won’t keep you up at night with a lot of noise. The unit has full-width, top, two-way control for air direction. It also comes with mechanical rotary controls.

“If you have a smaller space to cool and a smaller budget to work with, the Frigidaire FFRA0511R1 is a simple air conditioner for any room up to 150 square feet making it a good pick for home offices,” said The Spruce. “This 5,000 BTU unit gets experts’ top marks for effectiveness and solid marks for noise, but it costs a lot less than most other window units.” The unit is also recommended by Consumer Reports.

The mesh filter can be removed from the side and washed to reduce room odors, airborne particles, and bacteria. This makes for an environment that is both more comfortable and healthier for you and your family. The unit has a low-power start-up process that will save money by conserving energy. The restart will automatically resume once the power has been restored, operating at the earlier selected setting.

This A/C unit is easy to install in your window and comes with two cooling speeds and two fan speeds in addition to its two-way air direction. It cools down the room very fast and keeps it cool for hours and hours. The machine is very simple and gets the job done but doesn’t come with many extra features. There is no digital thermostat, timer, or remote included, for example. Some users will appreciate its simplicity while others may wish for more.

At just 12 by 15 by 16 inches, this air conditioner is definitely a miniature unit. But side panels can be installed to make it fit into windows as wide as 36 inches. It’s lightweight and makes less noise than larger units, though there is still some white noise present when the machine is on. Some may see this as a pro since it drowns out noise from outside. I, addition, the FFRA0511R1 doesn’t require a single-circuit wall socket to function and has great temperature control.

For the best results, use this in an insulated room and try to keep it out of direct sunlight on very hot days. Keep in mind that the unit is intended to cool just a room, not an entire level of your house. It also has a one-year warranty included.

hOmeLabs Window Air Conditioner

Runner Up

BTUs 5000
Dimensions 16 x 15.4 x 12 “
Weight 36 lbs
Cooling Area Up to 150 sq. ft.
EER 11.1
Estimated Yearly Energy Cost $41

The runner-up choice on our list, this air conditioner is a 5,000 BTU unit meant for indoor rooms 150 square feet and smaller. This hOmeLabs model comes with an air conditioner kit including window seal foam, leaf covers for the side panels, a support bracket, filter, and a user guide detailing drip-free installation instructions. For optimal results, the machine should be used in a small apartment, bedroom, or RV.

“This best-selling window-mounted air conditioner features seven speeds and two cool and fan settings,” said Popular Mechanics. “An included installation kit has leaf guards and the unit has a washable feature which can be reused season after season.”

If you own a lot of electronics and keep them in a small room, this A/C will help you keep the room temperature down and combat the heat they produce. To cool down your room quickly, just use the quick cool option on this unit and you’ll have relief from the heat in about 10 to 15 minutes.

This quiet, miniature unit comes with two-way airflow, seven different speeds, and fan settings you can easily adjust. It doesn’t have any digital controls, but also costs less than units that do. The machine has a reusable filter that can be removed and washed with dish soap and warm water. Alternatively, you can use a vacuum to clean it. When washing with water, make sure the filter has dried completely before putting it back in.

The unit measures 12 by 16 by 15.4 inches and is best for windows between 23 and 36 inches wide and no taller than 13 inches. When you’re unpacking the machine, be mindful of the sharp edges along the back. Grab the sides instead of the back and front when you pick it up or wear gloves to protect your fingers.

Frigidaire FFRE0833Q1

Best for Medium-Sized Rooms

BTUs 5000
Dimensions 15.2 x 16 x 12 “
Weight 41 lbs
Cooling Area Up to 150 sq. ft.
EER 11.2
Estimated Yearly Energy Cost $40

The best small air conditioner unit for medium size rooms, the FFRE0833Q1 is an 8,000 BTU mini-compact machine and works for spaces 350 square feet and smaller. The machine will cool the space down quickly on hot days and operates quietly so you can sleep while it’s on. Recommended by Consumer Reports, this unit has a multi-speed fan and three speeds to choose from.

Both the operation and start-up conserve energy by using low power, while the electronic controls let you choose your preferred settings for comfort. It also has a display showing the temperature you’ve selected. This unit comes with a remote control that senses and displays the temperature so you can set it, see it, and maintain it from the comfort of your couch or bed.

The unit comes with a clean air ionizer that relieves allergies from impurities and pollen in the air and an 8-way design for comfort control. You can easily change the cool air direction no matter where you’ve mounted the unit in the room.

Unlike other machines, this unit isn’t extremely noticeable from outside and doesn’t protrude far out the window. It’s also much lighter at under 50 pounds and can be installed fairly easily. The filter can be easily removed and cleaned as needed while the directional blades on the unit are very efficient.

Unboxing and installing the unit can take as little as 10 minutes as it’s a straightforward process. Note that the bottom plate is irregular and slightly unconventional. The rear piece extends more than an inch down and may make sliding the unit in place above a sill more difficult, depending on the design of your window.

Haier HWE12XCR

Best for Large Rooms

BTUs 12000
Dimensions 20.1 x 14.4 x 20.5 “
Weight 70 lbs
Cooling Area Up to 550 sq. ft.
EER 11.3
Estimated Yearly Energy Cost $95

The best small air conditioner for large rooms, this 12,000 BTU unit is built to cool down rooms no larger than 550 square feet. It’s recommended by Consumer Reports, and like the GE AHM05LW mentioned above, has a magnetic remote control. It also has braille controls for blind or visually impaired users.

Choose between auto cool, three fan speeds (low, medium, or high), and three cooling speeds (low, medium, or high). Functions of this machine include “energy save” to conserve energy as it cools, the “cool” setting to cool down the air, “dehumidify” for humidity reduction, and a fan for air circulation. If you activate the energy saving function, the fan runs on low as the compressor turns off and returns to its previous setting when it kicks back on.

The machine has a digital display, electronic control panel, and a fully functioning remote. The controls are easy to navigate and simple to use. Although the stats for the HWE12XCR state that it works in windows 37.5 inches wide and smaller, it may fit in an even wider window since the fans extend outward on either side.

The unit cools down your room very quickly and the filter doesn’t have to be cleaned very often compared to other units. Although it’s powerful and gets the room temperature down quickly, it does so without destroying your power bill and costing a fortune. You can remove the filter to clean it by simply opening the compartment at front. There’s a button that will alert you that it’s time to clean the filter as soon as it’s necessary.

Overall, this unit has a reasonable price and comes from a reputable manufacturer. Although there are cheaper 12k BTU machines on the market, this one has some extra features and is suitable for those who like their room very cool. It’s clearly a well-constructed product built to last. Note that, though very effective at cooling, this unit is not as quiet as others.


Most Energy Efficient Small AC

BTUs 5500
Dimensions 12.4 x 15.3 x 18.5 “
Weight 45 lbs
Cooling Area Up to 200 sq. ft.
EER 12.2
Estimated Yearly Energy Cost $41

The most energy-efficient small unit on our list, the AHM05LW is an energy star-rated, 115-volt unit. It can be used in a window between 24.5 and 36 inches wide. Recommended by Consumer Reports, the unit can be programmed to start and stop when you want it to and will instantly cool your room down. It comes with a handy magnetic remote so you won’t lose the controller when it’s not in use. This 24-hour timer is a handy feature that isn’t found in many of the other models on our list.

The 5,500 BTU machine is quiet enough for you to sleep in the same room while it’s running. You can use it as a main A/C for a small apartment or as a backup unit when your central air conditioner breaks down or needs servicing. It’s not designed for storm windows, so make sure you plan accordingly.

If you’re installing this unit against metal housing, you may have to use caulk for a more trustworthy seal against the heat and bugs from outdoors. For installing this in impact windows, the seals and hardware included with the AHM05LW may not work and you’ll probably have to get creative and purchase extra implements.

This machine uses its condensate water for raising its Seer rating and cooling the coils instead of letting it drop outside. It comes with a plug that you may remove if you want to drain the water.

Keystone Window-Mounted

Low Cost AC

BTUs 5000
Dimensions 15.5 x 17.5 x 18.2”
Weight 45 lbs
Cooling Area Up to 150 sq. ft.
EER 11.2
Estimated Yearly Energy Cost $40

If you’re looking for a cooling solution for a smaller room, this Keystone unit is another great option. It’s small enough to fit into most standard window spaces and has a cooling area of up to 150 sq. ft – perfect for small living rooms, bedrooms, and attic spaces.

Despite that small size, this unit still packs a pretty mean punch. “Very formidable air conditioner for the size and money.” said one happy Amazon reviewer. “The temperature-sensing remote control is pretty cool… the backlit remote screen is nice, and ability to turn off all lighting on the face of the A/C unit itself is an appreciated detail”

It’s pretty lightweight too at only a couple of pounds heavier than our number one choice. It also has a respectable energy efficiency rating of 11.2, so if you’ve been using a larger AC unit up until now, expect to reduce your energy output and cut costs.

It also boasts some smart programming features that take the energy saving potential up another notch. For example, you can activate the energy-saver mode to conserve even more energy or activate sleep mode so that the unit can gradually increase the room temperature while you’re sleeping (thus reducing power output).

And speaking of sleeping, you’ll have no trouble with that with this Keystone unit as it’s super quiet. You’ll hardly notice it’s running. Two other features I should probably mention are the 1.3 pints per hour dehumidification rate and the auto-restart that saves your settings.

The best thing about this unit, though, has got to be the LCD remote control that makes it easy to control your temperature from the other side of the room. You don’t have to get up in the middle of the night and walk over to the unit to change your settings. You can do everything at the touch of a button.

Models Compared

Model Dimensions
BTU Cooling Area (sq. ft.) Estimated Cost (per year)
Frigidaire FFRA0511R1 15 x 16 x 12 41 5000 Up to 150 $41
hOmeLabs 16 x 15.4 x 12 36 5000 Up to 150 $41
Keystone 15.5 x 17.5 x 18.2 45 5000 Up to 150 $41
Frigidaire FFRE0833Q1 15.2 x 16 x 12 41 5000 Up to 150 $40
GE AHM05LW 12.4 x 15.3 x 18.5 45 5500 Up to 200 $41
Haier HWE12XCR 20.1 x 14.4 x 20.5 70 12000 Up to 550 $95

Useful Tips for Yearly A/C Maintenance

Before turning down the temperature on your window unit, you should ensure that it’s gotten its annual check-up. Air conditioning units need to be maintained on a regular basis to stay functioning at optimal capacity. By following these easy guidelines every year, you can save money on repair costs and energy bills and stay cool in your home or office.

  • Clean Out the A/C Vents: Regularly dusting is very important. If you’ve been putting this task off, now is the time to do it. You might also hire a professional to give your vents and air ducts a more thorough cleaning.
  • Change your Unit’s Filter: Make sure you stay on top of basic maintenance for your window unit, like changing the filter when it’s needed. While central air systems need a filter change every few months or so, a window unit will only require a yearly replacement. Mark this on your calendar so you remember to do it.
  • Check the Freon: Freon is a refrigerant used by most A/C systems as a cooling agent. Ideally, you won’t ever have to change or fill the Freon in your window unit. But when you’re doing your yearly maintenance check, it’s good to have a professional HVAC technician search for leaks.
  • Look for Blockages: The area of your unit that sucks air into its system must remain uncovered. This should be checked more than once a year.
  • Coil Fin Care: You’re A/C unit’s coil fins can get bent easily and lead to problems for the machine. These fins can, thankfully, be restored easily with a fin comb. Check that the amount of fins per inch match up to the teeth count of the comb you’re using so it can be used how it’s intended. Combing can restore the fins efficiently and bring your unit back to its original form.
  • Storing and Preparation: If your window unit is just used seasonally, it should be inspected thoroughly both before and after every season it’s in use. These routine maintenance steps must be followed before storage and once again before the season begins. Inspect the seals to check for gaps that could lead to cool air leakages.

If your unit is used more than just seasonally, get a protective cover to place over it in the winter. This will prevent damages that could harm its efficiency. Choose a covering that doesn’t obstruct airflow and will securely attach to the machine.

If you do hire an HVAC tech to check your Freon levels, have them look at the coils and electrical controls while they’re at it. They can calibrate the thermostat while they’re there, too. All of these rules will ensure that your unit stays functioning at its best and keeps you nice and comfortable even on the hottest of summer days.

Calculating your Running Costs

Small window air conditioners enjoy the benefit of having a comparatively inexpensive price point, and running costs are lower as well. There are several factors that influence your running costs, such as the units EER rating, which gives an idea as to how much power (watts) it consumes for the cooling output (BTUs).

Additionally, the running cost of a unit is also affected by the various settings that modern window air conditioners feature. For instance, a unit that is running on a fan-only setting will consume less electricity than one that is utilizing the full strength of its compressor.

Functions, such as timers and sleep mode can also prove to be the difference as sleeping with a timer on can result in extra savings as opposed to an air conditioner that operates throughout the night.


To figure out the running cost of your window air conditioning unit, start by figuring how much ampere the unit draws. Look for either the specification sheet of the unit, or search for the model number online.

Once you have the amperes, multiply it by the voltage power it consumes. A standard 8,000 BTUs window air conditioning unit consumes 6 amps and 110 volts.

6 x 110 = 660 watts – that is the amount of power your air conditioner consumes. To get the hourly rate of consumption, divide this number by 1000.

In this case, the example comes out to be 0.66 kWh (kilowatt hour). Multiplying it by the average unit cost per kWh across the United States will give you your units running cost per hour. Here’s the answer in this example:

0.66 x 12.43 cents = $8.2 cents/hour; or $61 a month.

How To Size A Window Air Conditioner Correctly

Buy an air conditioner too small, and you will sweat yourself through summer. Buy one that’s too big, and feel the ineffective dehumidification in the room. This is why buying an air conditioner that fits the space is important.

The size of the window air conditioner is dependent upon various factors, but none more important than the space size. You can’t expect a 5000 BTU unit to cool down a 650 square-feet room. As a rule of thumb, air conditioners need 20 BTU per square-foot of the space.

There are various other factors, such as is the room exposed to sunlight or not? How many people occupy the room? Is the unit being installed in a bedroom, kitchen, or lounge? Buying the right sized window air conditioner is imperative to ensure maximum cooling efficiency.

Installing Window AC Units

Small window AC units are not heavy and can be installed easily, and that is why many people look to install a window air conditioning unit by themselves.

Before you set out on your AC installation, ensure that the power outlet is within 5 feet of the unit’s dedicated window and that you have the tools required for the installation.

Prepare Your Window

Start by measuring your window and marking the center point to ensure the flanked panels reach the sides of your window evenly.

Then, slide the panels that come with your unit in their appropriate places and secure the adjustable panels with screws. Screws not tightened enough can result in instability and the unit falling.

Install The AC Unit

Open the window and lift the air conditioner into the window. While the unit is capable of being lifted by a single person, having a pair of extra hands ensures there is enough stability and balance for a job well done. Tightly close the window on the top with most of the unit hanging outside the window, so make sure the unit is secured and tightened in the place.

Attach Panels And Brackets

With the laborious part of the task behind you, finish up your installation by screwing the L brackets and the accompanying panels to prevent the air conditioning from loosening or being pushed up.

If provided, add padding to the side of your unit for maximum security. Once you’re done installing the panels and brackets your work is done! Turn on your AC and enjoy the cool change in temperature.

Below is a video guide to installing a window air conditioner in your home.

Other Smaller AC Alternatives

While window air conditioners continue to lead consumer preferences in regards to an optimal cooling option for small spaces, there are other smaller air conditioning alternatives available, such as:

Wall Mounted

Wall mounted air conditioners, also called split system air conditioners, are easy-to-install and come with the advantage of being remote controlled. As one of the most popular air conditioning options used worldwide, split air conditioners offer excellent cooling as well as heating functions. However, compared to windows and portable they are on the heftier side and require a professional to install them correctly. Add their power consumption charges, and they are the most expensive option among the three alternatives.


Portable air conditioners as the name implies, these have the distinct advantage of being easily moved around. They require a very easy window duct installation after which they can function immediately. Some even come with added heating capabilities for winters. However, portable air conditioners can be expensive and use up a considerable amount of energy to cool small spaces. Their power levels may prove insufficient for some users, making for a hefty bill.

Frequently Asked Questions

How Many Watts Does A Small Window AC Use?

A small window air conditioner can use anywhere from 500 watts to 800 watts on average, whereas the medium and larger units consume in the range of 900-1440 watts.

How Many Amps Does A Small Window AC Unit Use?

Small window air conditioning units are usually energy-efficient, and the amperage rating can range from 15 amps to 20 amps.

How Do You Clean One Of These Tiny Air Conditioners?

Cleaning a small window air conditioner doesn’t have to be tedious. Unscrew the front panel, take out the filter, wash it and let it dry. Next, vacuum the evaporator coils thoroughly using the brush attachment and follow the same procedure for the condenser coils at the back. Lastly, if any coil fin seems bent, use a fin comb to straighten them out.

How Long Is The Warranty On These Models? Can I Purchase A Longer Warranty?

Most small window air conditioners come with the standard 1-year warranty, which covers services and any manufacturing defect that could lead to a problem in the unit’s functioning. Along with the standard warranty, some manufacturers also allow buyers to buy extended warranties (3 year – 5 year) for an additional premium of 10-25% of the purchase price.

Where Are Some Of The Top Sites To Buy Cheap AC’s Online?

Some of the top sites to buy cheap air conditioning systems include:

  1. Amazon
  2. HomeDepot
  3. BestBuy
  4. Flipkart

We recommend Amazon due to their extensive range, fast reliable shipping and above average returns policy.


Window air conditioners provide consumers the necessary escape from the scorching heat of the summer, without straining the pocket thanks to their energy efficient operation.

After a careful and thorough analysis of the available alternatives to choose the best small window air conditioning options for you and our preferred choice is the Frigidaire FFRA0511R1. With its two-way air direction and mechanical rotary controls, this unit provides exemplary performance for small rooms of up to 150 square feet.

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