Air Conditioner Sizes to Choose From


Air conditioners come in a variety of sizes not only on the outside but also in terms of power capacity. It is important to know the power output of your air conditioner in order to know if it is the right option for the space you are trying to cool off.

Quick Air Conditioner Size Guide

Area To Be Cooled (square feet)Capacity Needed (BTUs per hour)
100 to 1505,000
150 to 2506,000
250 to 3007,000
300 to 3508,000
350 to 4009,000
400 to 45010,000
450 to 55012,000
550 to 70014,000
700 to 1,00018,000
1,000 to 1,20021,000
1,200 to 1,40023,000
1,400 to 1,50024,000
1,500 to 2,00030,000
2,000 to 2,50034,000
Air Conditioner BTU Size Guide

10 Popular Air Conditioner Sizes in BTU:

Below we have a more detailed look at the 10 most popular air conditioner sizes measured in BTUs. The spaces they are ideal for, how much it costs to run them, and the types of use they are targeted towards. The aim of the article is to help you select the best unit for your needs.

Note: We mostly discuss portable and window-mounted air conditioners, as they’re the most popular air conditioners bought online, and do not require professional installers. We do however discuss wall-mounted air conditioners in the last three air conditioner sizes.

5000 BTU Air Conditioners

Popular 5000 BTU Window-Mounted Air Conditioner from Frigidaire.

Air conditioners of the 5000 BTU family are the smallest you can get on the market. They can be portable or window-mounted and are usually ideal for smaller rooms and spaces of up to 150 square feet.

Most of them are energy efficient with Energy Star certificates and can save you quite a bit on your utility bill. At the same time, some of the portable units can be very loud and are not as efficient even for that small space even though there are some which state that can cool up to 200 square feet and more.

The window-mounted ones are easy to install and do not take that much space. Price range is not too high and great deals could be found all over the place as long as you are sure you want a smaller unit. 

6000 BTU Air Conditioners

Popular 6000 BTU Window-Mounted Air Conditioner from Friedrich Chill.

Staying in the small leagues, the 6000 BTU air conditioners are a step up from the previous options but not by much. With a capacity to cool up to 200 square feet it makes for quite a treat for any dorm, small office space or maybe a small garage or tool shed.

Again the name of the game is energy efficiency because in this range you are looking for a small unit that could still get the job done but not consume too much energy to make you regret it looking at the bill at the end of the month.

There are many options to choose from all of which come with pretty basic functions and controls and, most of the time, at a higher price than some more powerful options. With this energy output, however, you want to be cost-efficient and getting a bigger unit, though sometimes less expensive might run you down the line with higher bills.

8000 BTU Air Conditioners

Popular 8000 BTU Portable Air Conditioner from Black and Decker.

Moving along and up to the 8000 BTU air conditioner units. Only 3000 BTUs more than the first entry but with the capacity to cool off twice the size of the room. At 300 square feet, we are now looking into a good living area, bedroom, garage or kitchen.

A little bulkier than the others, but there are still plenty of options to choose from. Window mounted units need to be set in place carefully and be secured properly so you do not hear a bang out and it comes crashing down off your window.

On the other end of the spectrum, the portable 8000 BTU air conditioners are usually easy to move from room to room but it needs to be said that in general portable air conditioners are able to cool much less space than the window-mounted ones of the same power level.

Some portable units are also quite loud when operating on high settings, which is not acceptable for some. Most available models in this range are also Energy Star certified so you can be sure these units are cost-effective and conserve energy so that your electric bill stays low. 

10000 BTU Air Conditioners

Popular 10 000 BTU Window-Mounted Air Conditioner from Tosot.

Looking at the 10000 BTU air conditioners we start to see some noticeable differences. There is a huge bump up the scale here, as these units will effectively cool of space of up to 450 square feet. There are, of course, ups and downs when we go bigger so let us take a closer look.

First of all, these BTUs will make sure you always stay cool and feel comfortable. It does not take long for a unit of this power level to cool a large room or master bedroom in about 15 minutes and maintain the temperature for as long as you need.

With the advanced technology in most of the new air conditioners, you would be able to run it all night with it usually adjusting the temperature by a degree or two every 30 to 60 minutes if need be, so you can sleep without your body cooling off as usual.

Their dehumidifiers make sure to extract the damp air and small dust particles that can be extremely useful in humid areas or climates. This also helps fight fungus as it is always cool and dry when you want it to be. Now, this is all fine and dandy until you get the bill at the end of the month because a unit of this size can run on about $100 a month, which would be just for your cooling.

The price of the unit itself can be sky high just because of the brand name, however, these tend to pay off with more energy efficiency. At the same time, both portable and window mounted 10000 BTU air conditioners can be very loud.

Some even go up to 80 decibels, which is to nobody’s liking especially if you are using it where you sleep or try to relax. Take a good amount of time to research and find the right one for you as it is an expensive investment.

12000 BTU Air Conditioners

Popular 12 000 BTU Portable Air Conditioner from Midea.

Kicking it up a notch let us look into the 12000 BTU air conditioner units. The first two things to take into consideration when you are looking to buy an air conditioner of this capacity are how much space do you need to cool and how much money and energy you can save while doing it.

Depending on the location and what type of space you are looking to work with, 12 000 BTUs can easily cool up to 500 square feet. Knowing that you have to make sure you opt for a unit with a great Energy Efficiency Rating (EER). Any number above 10 on that scale makes it a great energy-effective unit, with all numbers above that are Energy Star certified.

This energy scale lets you get an idea of how efficient your device is while using the energy it requires to run. Most of the air conditioners in recent years have very easy to clean filters, which and are eco-friendly in order to clean the air of bad smells and odors, while at the same time making sure the small dust particles stay out of the room. 

There is hardly any noticeable difference between window mounted and portable units. Window mounted devices are usually more powerful because unlike portable air conditioners they intake fresh air directly from the outside. The main benefit of portable units, however, is their ability to be moved around the house and from one space to another with relative ease.

The power consumption continues to go up, around 900-1300 watts of energy as we get to the higher BTU numbers but some more expensive models with high EER numbers are sure to save you money and energy in the long run.

14000 BTU Air Conditioners

Popular 14 000 BTU Portable Air Conditioner from h0melabs.

14000 BTUs is quite a punch-packed in an AC unit. Most models of this level can easily cool an area of about 400-500 square feet. Interestingly enough, people who look for this range, usually go for portable air conditioners.

There are plenty of models to go around but more and more portable ones come with great extra features and functions compensating for the usually smaller space coverage compared to the window mounted ones. There are more than enough models with heating mode, which makes for an excellent feature.

In addition, newer air conditioner units come with the ability to be operated from your phone via applications or in some cases even voice activating and setting them up with your home assistants like Alexa. This allows users to completely synchronize the use of their air conditioner with their own schedule and make sure the house or office is always ready for them from the moment they enter till the time they leave.

Most 14 000 BTU models run at about 1.7 kW per hour so make sure to check energy prices in your area to calculate potential usage and how much it would cost. Energy-efficient units will save you a lot of money long term if you decide to invest more in the initial purchase.

When it comes down to differences between window mounted and portable air conditioners there are not too much to point out. This is especially true when you are looking to cool the kitchen or the living room, as both usually have well-placed windows easily accessible by the hoses of the portable units as well as the window mounted devices.

15000 BTU Air Conditioners

Popular 15 000 BTU Wall-Mounted Air Conditioner from TCL.

We are halfway through our list and this next level of 15 000 BTUs is sure to please most of the high expectations of anyone looking into larger-scale units. You certainly do not need a huge central air conditioning system to feel comfortable in a small home or apartment.

A window-mounted air conditioner of this caliber is more than enough for complete comfort in a specific room. Most models make easy work of 500 to 700 square feet of space, more than enough for an office or a workshop. If you are looking for the high end of square footage, some models might prove to not be powerful enough so make sure to research different options before purchasing.

Energy efficiency is highly sought after in the higher BTU ranges because the higher the rating, the more money you will be saving in the future, as well as energy. Large air conditioners mean a lot of humidity so dehumidifiers in these devices have to be up to par to keep up with the needs of the user. A capacity of removing about 3 pints an hour or more is close to an excellent stat.

If operated at normal settings the usual power consumption of these devices comes up at around 1500 watts per hour which would not be a bad deal if the price of electricity is in a normal range. Most models do not have many differences from one another and mainly the features are the deciders for every user’s personal preference.

From touchscreen panels to adjustable noise levels and automatic on/off modes there is plenty of bells and whistles to choose from, however, the most important ones to look for stay the same – space coverage and energy efficiency.

18000 BTU Air Conditioners

Popular 18 000 BTU Air Conditioner from Daikin.

Getting to the high levels of air conditioners, let’s have a look at the 18 000 BTU units. These hard hitters are mainly used to cover large rooms and are used in commercial as well as residential spaces. If you are looking for a device to cool a whole apartment or a floor of your house, this is the perfect solution.

Air conditioners of this size are able to cool rooms of up to 1500 square feet, so a decent-sized office space makes for another great space to use this unit. Due to the size of the 18000 BTU air conditioners, they are usually wall-mounted, however, there are some who can also be mounted on windows but require proper fixation and safety precautions because of their weight.

Even though there are a small number of portable 18000 BTU air conditioners, they are rarely an option. With dehumidifiers that can remove about 5 pints of water an hour, they are a powerhouse when it comes to keeping the air cool and dampness free.

The eco filters are just as big and make sure no bad odors and small dust particles come through and lower the air quality in the space. Units of this size are made to be very energy efficient and will probably cost you about $150/month to run throughout the year.

Another great feature on these is most of them have a heating function and you can usually set the unit up in a way to keep the exact same desired temperature automatically as it either uses its power to cool off or warm-up space. In conclusion, any of the 18 000 BTU air conditioners are a good choice so all you should be looking at is price tag and energy efficiency.

20000 BTU Air Conditioners

Popular 20 000 BTU Wall-Mounted Air Conditioner from Daikin.

Moving into the last two sizes we cover in this article we are coming in at the 20 000 BTU mark. These are usually wall mounted units with a few exceptions, which are capable of cooling an area of around 1500 square feet and up. Perfect for commercial use in your store, bar, office or a larger scale floor of your house.

For example to keep one floor cool in the summer, while the other like the kitchen or living area warmer. Most of these units have a heating tube that allows year-round usage and the ability to warm up the place during winter or in most cases just maintain a certain temperature the same no matter the season or outside factors.

Make sure to research well when you decide to go for one of these because not only are they priced high but can hit you in your wallet just as much if you do not opt for a more energy-efficient model. All units are usually with good EER rating; however, a few points more than some models can make a huge difference in the end.

Another great feature, which cannot be overlooked, is that many of these air conditioners come with a big warranty, in some cases up to 7 years which can help you rest assured your money would be well spent and life longevity is great. These are a few of the wonderful benefits you get from buying a 20 000 BTU air conditioner.

25000 BTU Air Conditioners

Popular 25 000 BTU Wall-Mounted Air Conditioner from Frigidaire.

Finally, we draw our attention to the 25 000 BTUs units. The air conditioners to which you look when you need to cool off or heat a large office space or a decent-sized apartment from 1500 square feet and beyond.

With this size of the unit, you need the dehumidifiers to be top-notch and most usually remove up to 11 pints per hour. You can go for a window-mounted unit as strange as it may sound, and save up wall space or go for the more conventional wall-mounted option.

These air conditioners can set you back quite a bit on your utility bill, however, they are highly energy efficient in most cases. Using these to heat an area usually halves the space you can cover but it is normal, though 700-800 square feet is not bad to keep warm during the cold months – whether a living room or a bigger office space is not at all bad.


To summarize it all in a few final words, every BTU size has its pros and cons but it is up to you to make a wise educated decision. In this article, we covered the key details about the most common BTU sizes to ensure that you are confident and knowledgeable the next time you go shopping for an AC unit.