Size matters when you’re buying a window air conditioner.
An air conditioner that’s too small will struggle to keep a room at a comfortable temperature. A model that’s too big will cool a room too quickly without removing enough humidity from the air, leaving you cold and clammy.
More on Cooling
Choose just right and you’ll feel just right—and save money, too. Consumer Reports tests air conditioners in rooms that are the same size as the ones they’re intended to cool. That makes it easier for you to select the best model for your needs.
After installing a window air conditioner in a double-hung window in our lab’s climate-controlled chamber, we crank the air temperature up to 90° F and measure how long it takes the AC to cool the room by 10° F.
“The best models in our tests can cool the room in less than 15 minutes,” says Chris Regan, the engineer who oversees CR’s air conditioner tests.
We also gauge how accurately the AC reaches the set temperature, whether each model can recover after a simulated brownout, how intuitive the controls are, and how loud each unit is while running on low and high.
What Size Air Conditioner Do You Need?
Bedroom or home
sq. ft. 100 to 250
Primary bedroom or
sq. ft. 250 to 350
Living room, family room,
or open plan
sq. ft. 350 to 550
The Rules for Keeping Cool
Window air conditioners typically have a cooling capacity ranging from 5,000 to 12,500 British thermal units (Btu/hr.). As a general rule, an air conditioner needs 20 Btu for each square foot of living space.
But other considerations, such as the ceiling height and the size of your windows and doorways, might call for more cooling power.
To measure your room, multiply the length by the width. Add together the size of rooms that aren’t separated by doors, because the air conditioner will need to cool both spaces. 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 Btu for each additional person.
• If the unit is used in a kitchen, increase capacity by 4,000 Btu.
Best ACs for Small Rooms
For a small bedroom, home office, or guest room, ranging from 100 to 250 square feet, look for an air conditioner with a capacity of 5,000 to 6,500 Btu. You’ll want one with good scores for comfort and noise. Here are three top-rated models.
Best ACs for Midsized Rooms
To cool a bigger or busier room ranging from 250 to 350 square feet, you’ll want to step up to a midsized air conditioner rated at 7,000 to 8,500 Btu. If it’s for a bedroom, heed our noise scores. Here are three top picks.
Best ACs for Large Rooms
For a living room or family room of 350 to 550 square feet, you’ll want a large air conditioner with 9,800 to 12,500 Btu, especially if you have an open floor plan. Here are three solid choices.
Money-Saving AC Tips
Tougher federal energy standards for window air conditioners make newer models cheaper to run. Look for a unit with an Energy Star label and an energy-efficiency ratio (EER) of 10 or above. The higher the EER, the lower your operating costs. All the models in CR’s air conditioner ratings have an EER of 10 or higher.
Keeping your AC in peak condition can also help you save. Look for a model with a filter that’s easy to remove for regular cleaning. A dirty filter causes an air conditioner to work harder.
Many air conditioners have a timer that you can set to cool a room before you get home. And some have an app for your smartphone that you can use in case you forget to do it before you leave the house.
Maintaining Your Air Conditioner
We rely on our window air conditioners to keep us cool when temperatures climb. On the “Consumer 101” TV show, Consumer Reports expert John Galeotafiore explains to host Jack Rico how to maintain a window AC unit to ensure cool, clean air throughout summer.
Mary H.J. Farrell
Knowing that I wanted to be a journalist from a young age, I decided to spiff up my byline by adding the middle initials "H.J." A veteran of online and print journalism, I've worked at People, MSNBC, Ladies’ Home Journal, Good Housekeeping, and an online Consumer Reports wannabe. But the real thing is so much better. Follow me on Twitter.
What size room will a 12000 BTU air conditioner cool? ›
12,000 BTUs will cover 400 sq. ft. (3,200 cubic feet) 13,000 BTUs will cover 450 sq.How many BTU do I need for a 12x12 room? ›
Obviously, the problem arises when you have a tiny 12×12 room, for example. According to the US Department of Energy directive, an air conditioner's most appropriate size would be 2,880 BTU unit.How many square feet will a 8000 BTU air conditioner cool? ›
At 8,000 BTU, it has the cooling capacity for up to about 350 square feet.How big of an AC unit do I need for 2000 sq ft? ›
For example, when considering what size air conditioner is needed for a 2,000 square foot home, you would likely choose a 3 or 3.5 ton unit, depending on the climate where you live.What happens if BTU is too high? ›
A unit with too many BTU's, will cool the room fast, but leave the room humid. Too few BTU's will never cool the room down and the unit will run incessantly.Is 12000 BTU too much for a bedroom? ›
You also don't want to buy a model that's too powerful for a room. Sure, a 12,000-BTU air conditioner will cool a small space (150 square feet or less) quickly. But it might cool it too quickly, preventing it from removing some of the ambient humidity from the room and leaving the room damp.How many square feet will a 10000 BTU air conditioner cool? ›
Specifically, an 8000 BTU air conditioner can cool a 300-400 square foot room, while a 10000 BTU air conditioner can cool up to 500-700 square feet.What is the square footage of a 12x15 room? ›
Living room: 12 feet x 15 feet = 180 square feet.How many BTU do I need to cool a 10x20 room? ›
So a room that is 20 feet wide and 10 feet long is 200 square feet, which requires an output of between 6,000 and 7,500 Btu per hour. Increase the number of Btu by 10 percent if the room is in direct sunlight, and reduce it by the same amount if the room is well shaded.
If you have a 1,200-square-foot home, you'd need a two-ton unit. A 2,400-square-foot home would need a four-ton unit. Again, there are 2.5-ton and 3.5-ton units in case your square footage doesn't work out perfectly for a two- or three-ton unit, for instance.
What size air conditioner do I need for a 12x12 bedroom? ›
As a general rule, an air conditioner needs 20 Btu for each square foot of living space. But other considerations, such as the ceiling height and the size of your windows and doorways, might call for more cooling power. To measure your room, multiply the length by the width.What is the difference between 12000 BTU and 18000 BTU? ›
For a room of 35-60 square meters – you need air conditioning capacity of 12000 BTU. Those who have a home area of 60 to 80 square meters – require an air conditioner with a capacity of 18000 BTU.What is the recommended BTU for a room size? ›
Generally, your temperature control system should have 20 BTU for every square foot of living space in the area you wish to heat or cool. For example, if your room or area is 400 square feet in size, then you should opt for a temperature control system with a capability of around 8,000 BTU.