Size matters when you’re buying a window air conditioner. Buy too small and it will struggle to keep the room at a comfortable temperature; buy too big and and the room will cool too quickly without removing enough humidity from the air. Buy just right and you’ll be comfy and save money too. At Consumer Reports, we test air conditioners in the size rooms that they're intended to cool. Here are the best small, medium, and large window air conditioners from our tests.
Bedroom or office (100 to 300 square feet)
For a small bedroom, home office, or guest room you’ll want an air conditioner with good scores for comfort and quiet.
The GE AEM05LS, $210, a CR Best Buy, aced our comfort tests and was very quiet on both low and high fan speeds.
The GE AEM06LS, $230, was very good at cooling a small room and just as quiet as its brandmate. Similar models are sold at Home Depot and Sam’s Club.
Master bedroom or playroom (250 to 400 square feet)
To cool a bigger or busier room, you’ll want to step up to a mid-sized air conditioner.
The LG LW8014ER, $240, was tops in its class with very good scores for cooling a medium-size room. But it was a bit noisy when the fan was on high.
The Friedrich Chill CP08G10A, $380, was quieter so perhaps a better choice for a bedroom. Its comfort scores were just as good.
Living room or family room (350 to 650 square feet)
For a living room or family room, you’ll want a large air conditioner, especially if you have an open floor plan.
The LG LW1214ER, $350, made our top picks list with its excellent scores for comfort. And despite its size, it operates at a quiet hum. None of the other large units in our tests made the recommended list.
Size up your needs
Window air conditioners typically have cooling capacities ranging from 5,000 to 12,500 British Thermal Units (BTUs). But don’t buy by BTU alone. As a rule of thumb, an air conditioner needs 20 BTU for each square foot of living space but there are other considerations such as the height of your ceiling and the size of your windows and doorways. To measure your room, multiply the length of the room by the width. Energy Star recommends that you make adjustments for the following circumstances:
If the room is heavily shaded, reduce capacity by 10 percent.
If the room is very sunny, increase capacity by 10 percent.
If more than two people regularly occupy the room, add 600 BTUs for each additional person.
If the unit is used in a kitchen, increase capacity by 4,000 BTUs.
Install it correctly
To get the most from your window air conditioner, install it right. If your window is not in the center of your room, check that the direction of the airflow is into the room, not into the corner. Here are some tips from EnergySavers.gov.
Make sure it’s level so the drainage system works effectively.
Check your outlets. Some larger units need a dedicated circuit.
Don’t put lamps or TVs near the air conditioner’s thermostat as the heat will cause it to run longer.
Set the thermostat as high as is comfortable, typically 78° F. You’ll appreciate the savings.
Don’t dial the temperature down when you turn the air conditioner on—it won’t cool the room any faster.
On humid days, set the fan speed on low; the slower air movement removes more moisture from the air.
Use an extra fan to spread the cooled air around.
Save energy too
Energy standards for window air conditioners are getting tougher, making them cheaper to run. Look for an Energy Efficiency Ratio of 10 or above. The higher the EER, the more efficient the air conditioner. Look for models with filters that are easy to remove for regular cleaning. All the air conditioners in our tests have remote controls, digital displays, and timers that you can set to cool down the room before you get home.