The 6 best air conditioners we tested in 2021

Table of Contents: Masthead Sticky

  • A good air conditioner is energy efficient, runs quietly, and cools your space quickly.
  • The Friedrich Chill Premier Smart Window Air Conditioner is our pick for the best air conditioner.
  • It did the best in our cooling tests, features app connectivity, and is Energy Star-certified.

For those who don’t have central air to cool their space, window air conditioners are the next best thing. They can fit in most windows for convenient cooling, and if you choose one that’s Energy Star certified (which most of our picks are), your bills won’t run up too high.

Despite what you may see in the movies, window ACs are relatively easy and safe to install as long as you follow each unit’s instructions, and many models come with brackets that keep the air conditioner in place and prevent potential burglars from pushing units in and getting inside your home.

To determine the best air conditioners, we tested 10 models (details on our testing methods here) and consulted with Matt Brown, the merchant for home comfort, air quality, and floorcare at The Home Depot, and Enesta Jones, a spokesperson for the US Environmental Protection Agency (EPA), which oversees the Energy Star program. Our guide features units that performed well in our tests, have useful features, and are energy efficient.

If you are searching for portability, we’ve included our top portable AC pick in this guide, but you might also want to check out our guide to the best portable air conditioners.

Here are the best window air conditioners in 2021

The best overall

best air conditioner overall 2021 friedrich

If you have a medium-sized room, the Friedrich CCF08A10A Chill Premier Smart Window Air Conditioner is your best option with its impressive cooling abilities, smart connectivity, and long warranty.

Pros: Did the best in our cooling tests, smart connectivity with a useful app, fits a wide array of window sizes, five-year warranty on sealed refrigerant system, Energy Star-certified

Cons: One of the loudest units in our tests

Of the 10 units we tested for this guide, the Friedrich CCF08A10A Chill Premier Smart Window Air Conditioner did the best job of cooling our 650-square-foot test room. During the one-hour testing period, the temperature dropped 5.3 degrees Fahrenheit. 

It was also easy to install, taking only 20 minutes plus an extra 10 minutes to install and connect the smartphone app (available for iOS and Android), which lets you set schedules and control your AC from anywhere. 

The Friedrich Chill Premier is Energy Star-certified, and in our tests, it was in the middle of the pack in its power consumption. It used 0.4 kWh of energy while we blasted it on high for one hour. 

Our only complaint is that it was one of the loudest ACs in our tests, registering 56.3 decibels on high, which is a little bit louder than the average refrigerator. Even on low, our sound meter registered 54.8 decibels, which is quite noisy. 

Best budget

Best budget air conditioner 2021 GE

The GE AHY08LZ EZ Mount Window Air Conditioner is your best bet if you’re looking for a cheap way to cool your room, with its low-decibel output, outstanding cooling, and easy installation.

Pros: Energy Star-certified, performed well in cooling tests, easy to install, quiet operation

Cons: Unable to access smart features, unimpressive CEER rating, minimal warranty

The GE 8,000 BTU Smart Window Air Conditioner (model AHY08LZ) features a relatively light weight of 54 pounds and is simple to install. I had it up and running within 20 minutes of opening the box, and it fit my slender 24-inch-wide window frame.

More importantly, it’s a workhorse. In our test room of 650 square feet — nearly twice what the unit is rated for — the GE was able to decrease the temperature by more than 3 degrees F in an hour. It did this while remaining fairly quiet, registering only 55 decibels on high, which makes it suitable for bedrooms and home offices.

Its control panel shows the temperature in large, easy-to-read numbers and automatically dims to keep light to a minimum if you’re using it in the bedroom at night. The face also features adjustable louvers that allow you to send cool air precisely where you want. 

The GE has Wi-Fi connectivity and can be operated remotely, but I could not get it to connect with GE’s Comfort app (available for iOS and Android). After several tries, I still couldn’t use any of the smart features. Based on the 2.9-star rating in the Google Play store and 1.9-star rating in the App Store, I’m not alone. 

I reached out to GE about the app issues, and it responded quickly. According to the company, it’s a known issue for some users but it did not have a timeline for when it would be fixed. However, even without the smart features, this is an outstanding unit.

Best energy-efficient

Best energy efficient air conditioner 2021 midea

The Midea MAW08V1QWT U Inverter Window Air Conditioner features a unique U-shape design that allows you to open the window when it’s installed, and it’s one of only a few ACs to earn Energy Star’s “Most Efficient” certification.

Pros: Unique U-shaped design, Energy Star “Most Efficient” certification, easy to install in a wide array of windows, comes with a support bracket, quiet 48-decibel operation, smart connectivity that works well

Cons: Can only change airflow direction horizontally

The Midea MAW08V1QWT U Inverter Window Air Conditioner has a unique U-shaped design that offers more secure installation when combined with the included support bracket — hardware rarely included with AC units — and allows you to open and close the window to let in fresh air. 

It’s the first window AC to receive the Energy Star “Most Efficient” certification, and it remains one of only three models to receive that designation — another is the LG Dual Inverter AC, our pick for the best AC for large rooms. 

The Midea U uses inverter technology to achieve such impressive efficiency numbers. Inverter compressors have variable-speed motors that adjust to maintain the desired temperature. This constant low-level operation is actually more efficient than cycling high output on and off like traditional units do. According to my smart plug, the Midea U consumed 9.6 kWh over a 24 hour period, which works out to 0.4 kWh each hour.

Installation was quick, though the instructions could be a bit clearer. Still, I had the unit up and running within 25 minutes of opening the box. Connecting to the smart app was also quick and let me control the Midea U with my voice using Alexa.

I was impressed with how quietly the AC runs. The sound meter registered 48 decibels when it was operating on its highest setting. 

The only reason the Midea U isn’t our top overall pick is its lukewarm performance in our cooling tests. It only decreased the temperature of our 650-square-foot room by 1.7 degrees in the first hour — comparable to our budget pick. 

Best for small rooms

best air conditioner for small rooms 2021 haier

The Haier ESAQ406TZ Window Air Conditioner is ideal for bedrooms and home offices thanks to its ultra-quiet design.

Pros: Good cooling for its size, quiet operation, easy installation, seemed to improve air quality during testing, Energy Star-certified, multi-directional vent control

Cons: Requires a window width of at least 26-1/16 inches, minimal/standard warranty

The Haier ESAQ406TZ Window Air Conditioner registered the lowest noise output of any of the units in our testing. On low, our sound meter measured 41.9 decibels, which is almost as quiet as a library. Even on high, it was only a little louder than a normal conversation at 51.4 decibels. Coupled with the low Btu output, this is the ideal unit for bedrooms and home offices.

Installing the Haier AC was relatively easy and didn’t require any special steps. The process took me about 25 minutes. However, I found it surprising that such a low-Btu unit would require such a wide window opening.

The Haier was in the middle of the pack in cooling. It brought the room’s temp down by about two degrees in one hour. This is impressive considering it was one of only two units with less than 8,000 Btu that I tested. (The other, the GE AHQ06LZ, did a much poorer job.) I like that there are multi-directional vent adjustments so you can send the cool air where you want it most.

During testing, I used a handheld monitor to measure any changes to air quality, and it showed a significant reduction in VOCs and particulate matter.

Lastly, it’s Energy Star-certified, and that lined up with my experience with it. After an hour, it had used 0.3 kWh of electricity. It has an estimated yearly energy cost of about $52 according to government data.

Best for large rooms

best air conditioner for large rooms 2021 LG

The LG LW1517IVSM Dual Inverter Smart Window Air Conditioner provides an impressive combination of quiet operation, outstanding performance, and energy efficiency.

Pros: Good performance in our cooling tests, quiet operation, certified Energy Star “Most Efficient,” Wi-Fi connectivity with support for Alexa and Google Home, can be controlled remotely with a smartphone app

Cons: Pain to install, underwhelming one-year warranty, only works in windows at least 27-inches wide

This LG unit was one of the best in our cooling tests, dropping the temperature in a 650-square-foot room by 3.3 degrees in one hour. It was also one of the quietest, registering just 53 decibels when on high. 

LG was the first to use inverter technology in its air conditioners. The dual-inverter compressor of the LG LW1517IVSM Dual Inverter Smart Window Air Conditioner helped it earn the rare Energy Star “Most Efficient” certification.

Home Depot’s AC expert Matt Brown is a fan of this model. “LG inverter units are exciting because they offer the best smart connectivity, are much quieter than standard units, offer customers significant power and utility bill savings, and look very sleek and modern,” he said.

This is the main air conditioner I use on the ground floor of my home. Even on the hottest days, the LG LW1517IVSM keeps us cool. And, it remains quiet enough to facilitate normal conversation.

Installation was difficult, however. It took me two hours and included steps like removing and reinstalling parts from the unit. Uninstalling it for the winter was a task. Usually, I can carry air conditioners on my own, but I had to enlist the help of my teenage son when putting it in storage.

The LG can used with Amazon Alexa and Google Assistant. You can also use LG’s SmartThinQ app (available for iOS and Android) to schedule the unit and perform other remote operations.

Best portable

best portable air conditioner 2021 LG

The LG LP1419IVSM Dual Inverter Smart Wi-Fi Portable Air Conditioner is a well-rounded, energy-saving unit that can be controlled by your phone or voice.

Pros: Can be controlled and scheduled using your phone, voice control, easy to move, performed well in cooling tests, fits a wide array of window types and sizes

Cons: Set up took longer than others, one-year warranty, terrible energy efficiency compared to window ACs

*Editor’s note: This model frequently goes in and out of stock at many retailers. We’ll continue to update this post with availability.

Portable air conditioners have their benefits: namely portability and the ability to work with any outside opening. However, they vastly underperform compared to window ACs and no portable models are currently certified by Energy Star. While window AC units suck in hot air and vent it directly out the window, portable ACs rely on a long tube to carry air from your room to the outside. Along the way, heat radiates from the tube and stays in the room, so it takes a lot more energy (and money) to cool a room with a portable AC than a window AC. 

If you have a window that will accommodate it, we always recommend a window unit over a portable model. If that’s not an option, however, the LG LP1419IVSM Dual Inverter Smart Wi-Fi Portable Air Conditioner is your best bet.

The LG portable AC is our top pick from our guide to the best portable air conditioners because it’s quieter and more efficient than most portable models due to its dual-inverter compressor. It’ll take about double the time to cool a room than a window unit, but it’s very easy to install and use. 

After an initial 30-minute installation time (including connecting to the app), it was super simple to move from room to room. It only took about a minute to reinstall it in a new room thanks to its handles, smooth casters, and a dedicated slot for the window slider when in transport. We like that it can accommodate a wider range of windows than the other units in this guide.

It’s Alexa-enabled and also has smart capabilities through the LG ThinQ app (available for iOS and Android), which lets you schedule when the unit runs.

What else we tested

best air conditioner 2021 what else we tested

We’ve tested 10 air conditioners over the last year, and there are several that barely missed the cut for our guide but are worth considering.

What else we recommend and why:

Frigidaire FHWW083WB1 Smart Window Air Conditioner ($359): There’s a lot to like about this AC, but I couldn’t find a category that it was tops in. It did well in the cooling tests, the app works well, it fits a broad range of window sizes, and it seemed to improve the air quality while operating. The negatives are that it’s kind of loud and wasn’t particularly energy efficient. It’s occasionally on sale at a lower price than our budget pick. If you are looking for a deal and happen to find this Frigidaire unit marked down, I strongly recommend picking it up.

Windmill Smart Window Air Conditioner ($395): This was the loudest AC I tested at 63 decibels on high. It was also among the biggest power users and isn’t Energy Star-certified. Plus, you can’t adjust where the air flows. The Windmill was in the middle of the pack in cooling performance bringing the temp down by about two degrees in an hour. I also liked how incredibly easy it was to install and that it fits windows as small as 23 inches wide.

What we don’t recommend and why:

Friedrich Kuhl Series KCQ08A10A Window Air Conditioner ($869): This AC performed poorly in our cooling tests, and I spent half an hour trying to get the weird browser-based Wi-Fi connectivity to work without any success. On the plus side, it comes with a nice warranty, fits a lot of window sizes, and doesn’t use much power. But, at this price point, there are much better options out there.

GE AHQ06LZ Window Air Conditioner ($250): The only positives with this unit are it fits a wide range of window sizes and it doesn’t use much power. It did the worst in our cooling tests, only has bidirectional vents, didn’t come with insulation for the side curtains, and it seemed to have a negative impact on air quality.

GE PHC08LY Profile Smart Window Room Air Conditioner ($395.10): This was another model that I thought deserved a spot in our guide but didn’t quite fit anywhere. It was runner-up in our cooling test, decreasing the room temp by five degrees in an hour. However, it fell short in so many areas. Only the Windmill used more power. This unit only has left/right vent control and not up and down. I couldn’t get the app to connect to it. And, our air monitor showed a decrease in air quality, though it didn’t reach harmful levels.

Testing methodology

best air conditioner 2021 methodology

I personally tested all of the air conditioners in this guide. There are several objective tests I put each model through. The most important factors I consider are cooling abilities, energy efficiency, and special features.

Here are the main attributes we look for and how we test them:

Cooling: I set the unit up in a 650-square-foot test room. I measure the temperature from the opposite side of the room, run the AC on high for an hour, and then compare the readings. 

Noise: I use a sound meter positioned six feet away from the air conditioner as it runs on high. I also adjust the fan speeds and set point temperature to see if these changes cause off-putting sounds that could startle people nearby.

Extras: At a minimum, an air conditioner should come with a window installation kit, a remote control, dehumidifier and fan modes, and a delayed on and off switch. I also look for additional conveniences, like including foam to seal and insulate the openings around the AC. Wi-Fi-enabled smart capabilities are also a major plus, but I found there’s a lot of room for improvement in this area.

Energy efficiency: I look at whether the unit is Energy Star-certified as well as the unit’s combined energy efficiency ratio (CEER). The CEER is calculated by dividing the Btu output of the unit by the energy consumed while it’s operating and in standby mode. To receive Energy Star certification, most units need a CEER of at least 12 in addition to other requirements. I also perform my own tests using a smart plug to measure the power consumption while running the AC on high for an hour or more.

Installation: Though installation will likely only be a small part of your relationship with your AC, it’s an important one. Windows between 27 and 36 inches wide will accommodate most ACs, but if you have a 25-inch-wide window, it gets dicey. We look at what windows different models fit, how long it takes to install, if you need special tools, and how difficult it is to uninstall and reinstall it since you will likely need to do this each fall and spring.

Air quality: This is a newer test that we don’t weigh as heavily. We take air quality readings using a monitor to determine changes in the carbon dioxide, volatile organic compounds, and particulate matter in the room while the AC is running. The air quality didn’t enter the “harmful” range while running any of the ACs. However, we did note that the air quality readings changed significantly with some units. We’ve noted these in the guide.

What we’re testing next

We’re always looking for air conditioner models to test to ensure our guide is as comprehensive as possible. Here’s what we’re looking forward to testing before the next update:

Frigidaire Gallery Inverter Quiet Temp Smart Room Air Conditioner ($479): As of this writing, the new Frigidaire Gallery AC isn’t available anywhere. But, it’s already earned the Energy Star “Most Efficient” certification. Along with the Midea U and LG Dual Inverter, it’s one of three ACs to earn that distinction. We’re looking forward to testing it when it’s more widely available.

LG Smart Window Air Conditioner ($439.99): This is similar to our pick for best AC for large rooms, but it doesn’t use inverter technology. We’re curious to see how the cooling and efficiency numbers compare.

LG Window-Mounted Air Conditioner ($449.99): This model is similar to the one above, but it’s not Wi-Fi-enabled. Many reviewers recommend this unit, and we want to see if it lives up to the hype.

How to choose the right air conditioner

Best air conditioner 2021 how to choose

Matt Brown, the merchant for Home Comfort, Air Quality and Floorcare at The Home Depot says there are five primary factors to consider when shopping for an AC: Btu, room size, outlet type, window size, and extra features.

The room size, outlet type, and window size are entirely dependent on your space, and the extra features are dependent on your personal preferences. One thing you can’t compromise is the Btu of your air conditioner.

“ACs are rated by Btu (British thermal units) and range from 5,000 to 24,000 Btu, which correlates to 150 to 1,500 square feet. The larger the Btu, the larger the room it covers,” Brown says. “It’s critical to not get a unit too big or small for a room for maximum cooling and efficiency.”

The Department of Energy provides a helpful guide for determining the BTU that is right for your room size. If you get a unit that is too big for your room, it will cool too quickly without removing the moisture, which will create a cold, clammy environment. Alternatively, an AC that is too small will be overworked, which can boost your energy bills. 

It’s common for model numbers for the same units to vary by one or two digits. This is usually to denote different Btu ratings and colors, so it’s important to choose a model number that reflects the Btu rating right for your room.

How to turn any AC into a smart AC

A trend you’ll see in high-end window air conditioners is smart connectivity. This allows you to operate the unit remotely through an app on your phone, provided it’s connected to your home’s Wi-Fi network. This lets you turn on the AC before you arrive home from work, or turn it off if you had forgotten before you left the house. Some units even offer voice operation via Amazon Alexa, Google Home, or Apple HomeKit.

As useful as this feature may be, not all ACs have smart connectivity. And, we’ve found it doesn’t always work properly even when units do have the capability.

If smart connectivity matters to you, an option is to connect the unit to a good smart plug. This option will turn any AC into a smart appliance, giving you the aforementioned benefits. Some can even monitor the energy being used, so you can keep track of usage. Unlike an AC with smart connectivity built-in, the downside of using a smart plug is that you can’t adjust the temperature setting or modes — a smart plug simply turns the unit on and off, so you would have to adjust those settings in advance. You should also make sure that the smart plug can handle the voltage that the AC requires and is the correct outlet type.

One of the best smart plugs we’ve used recently with an air conditioner is the BN-Link WiFi Smart Plug Outlet. It’s easy to set up and we’ve had no issues connecting to it remotely from a smartphone — it also supports Alexa for voice operation when we’re at home. It’s very affordable, and it doesn’t require a hub — just your home’s Wi-Fi. Check out our guide on the best smart plugs and outlets if you would like more options.


Best air conditioner 2021 FAQs

How can you use your air conditioner efficiently?

According to Enesta Jones, a spokesperson for the US Environmental Protection Agency (EPA), which oversees the Energy Star program, there are several best practices:

  1. Make sure the unit is level.
  2. Don’t put lamps or TVs near the AC thermostat because the extra heat will cause it to run longer.
  3. Set the thermostat temperature only as high as is comfortable to save energy and money.
  4. Set the fan speed low on humid days to remove more moisture. 
  5. Use an extra fan to spread cooled air around.
  6. Remove the unit or use an appropriately sized cover at the end of the cooling season to minimize heat loss.

We’d also add that you should try to install your AC in a window that is shaded for maximum efficiency.

Can I use an air conditioner in a room without windows?

The short answer is yes, but you need to have some way for the hot air produced by the air conditioner to leave the room. If you don’t, you won’t experience any of the cooling benefits of the air conditioner. Most window air conditioners vent hot air out of the back and sides of the unit, but some only produce hot air out of the back. This variety can typically be installed in an outside wall. 

Portable air conditioners afford you more options since you just need an opening to the outside that is as big as the ventilating hose.

Which is better: a portable air conditioner or a window/room air conditioner?

“In general, a room air conditioner is a more efficient choice over a portable air conditioner,” says Jones. “Portable air conditioners are not part of the Energy Star program.”

Our testing backs this up. Our top portable air conditioner, which uses an energy-efficient inverter compressor, still used 60% more electricity than our top window air conditioner. Our top window AC also did a much better job of cooling and costs much less both upfront and to run.

The main reason portable ACs are so inefficient is that they send their hot air outdoors through a hose that is located indoors. So, a lot of the heat stays in the room. Window air conditioners on the other hand are mostly outside so the hot air has a harder time entering your room.

So, if you have a double-hung window with the right dimensions for it, we strongly recommend choosing a window air conditioner. Only opt for a portable AC in spaces where a window AC isn’t an option.


In the heating and cooling industry, there’s a lot of jargon to wade through. What do all of those acronyms and terms even mean? Here are the definitions for a few that you’ll commonly hear:

Btu: This is short for British thermal units. One Btu is equal to the amount of heat needed to raise one pound of water by one degree Fahrenheit. In cooling, Btu is used to measure how much heat is removed from a room. The more Btu per hour an air conditioner is rated for, the better job it does cooling.

CEER: “The CEER, or Combined Energy Efficiency Ratio, is a measure of energy efficiency for a room air conditioner,” Jones says. “The higher a room air conditioner’s CEER value, the more efficient the room conditioner is when comparing across models with the same cooling capacity.” The CEER is measured by dividing the Btu output by the amount of energy consumed both while the unit is running and while it’s in standby mode.

Compressor: The compressor works to push the hot air outside so cold air can circulate in your room. The gas refrigerant within the cooling system takes on the heat from the air, and the compressor turns the hot gas refrigerant back into a liquid. It works with the condenser on the air conditioner’s hot side to dissipate the heat from the refrigerant. Along with the condenser and evaporator, the compressor is one of the three main components of any air conditioning unit.

Energy Star: This is a program run by the US Department of Energy and EPA to promote energy efficiency. “Any window AC model that earns the Energy Star label is independently certified to save energy, save money, and help protect the climate,” says Jones. 

kWh: This is short for kilowatt-hour. It’s a unit of energy that most electricity utilities use to measure your power use, and it’s what we use to measure the energy consumption of the air conditioners we test.

Check out our other home heating and cooling guides

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