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).
In This Guide
Editor’s Top Choice For Small Window Air Conditioners
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.
Runner Up For Small Window AC Units
hOme 5,000 BTU Window Air Conditioner
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. It 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.
Best Small AC Unit for Medium-sized Rooms
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.
Energy Efficient Small AC Unit
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.
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.
Best Small AC Unit for Large Rooms
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.
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.