7 Best Air Conditioners for Small Rooms

Air conditioners for small rooms should not take up much space, effectively cool your room, and don’t consume much electricity.

In this article, we’re going to check the best air conditioners for small rooms.

Quick answer: The best air conditioner for small rooms is a 5,000 BTU window air conditioner. Getting a larger air conditioner and cooling your entire living space (instead of just one small room) is even more cost-effective because small rooms can’t keep the cold air for long and heat up quickly.

After we’ve looked at the best small-room air conditioners, I am going to show you with simple mathematics why getting a powerful air conditioner and cooling your entire home could make even more sense.

Let’s have a look at the full list first:

Best Air Conditioners for Small Rooms

We’re going to look at 3 different air conditioner & cooling device types:

  • Window ACs – generally the best ACs for small rooms
  • Portable ACs – also good, but need more power
  • Evaporative coolers – not real ACs, but enough to cool a small room

My favorite are window ACs, but if you want an easier installation, portable ACs are fine as well.

Window air conditioners are generally the best air conditioners for small rooms. Because they sit in a window, they don’t take up much space. And additionally, window air conditioners get you the most cooling capacity for the least amount of money.

#1 BLACK+DECKER Small-Room Window Air Conditioner (5,000 BTU)

My personal recommendation is this BLACK+DECKER window air conditioner (click here to view it on amazon).

I picked this one as the best air conditioner for small rooms because it takes up very little space and you can choose the cooling capacity you need.

Available sizes:

  • 5,000 BTU
  • 6,000 BTU
  • 8,000 BTU
  • or higher (but that’s too much for small rooms)

The smallest model is 5,000 BTU, which is perfect for small rooms and bedrooms. According to the manufacturer it is designed for up to 150 sq. ft. rooms. But I’d personally say 5,000 BTU is enough even for 200 sq. ft. or 250 sq. ft. rooms.

If you are unsure about which size to pick, just get the 6,000 BTU model. There’s also an 8,000 BTU option. But that’s way too big for most small rooms. And it’s twice the price!

#2 LG Window Air Conditioner (6,000 BTU)

My second place recommended window air conditioner for small rooms is this 6,000 BTU LG window AC (click here to view it on amazon).

I rank this one #2 because you have no other options than going for the 6,000 BTU cooling capacity.

So, this one might be a bit oversized for very small rooms. Nevertheless, it’s a good window air conditioner and you can’t really go wrong with it.

I could tell you all kinds of trivia about this window air conditioner, such as its low noise and that it has many settings… But actually, that’s standard nowadays, and most window air conditioners are the same.

To be honest, it does not really matter which window AC you get. All of them are technically identical, and they only differ in cooling capacity.

#3 Midea Window Air Conditioner (5,000 BTU)

My third choice would be this Midea window air conditioner (click here to view it on amazon).

There’s nothing that technically makes this one worse than the second-placed AC. All window air conditioners are technically the same.

This one is just another small 5,000 BTU window air conditioner that is perfectly sized for small rooms. This model also comes in different sizes:

  • 5,000 BTU
  • 6,000 BTU
  • 8,000 BTU
  • and higher

But you don’t really need anything above 6,000 BTU if your room is smaller than 250 square feet.

At the end of this article, I am going to tell you the ideal BTU rating for your room size. So, stick out until the end!

#4 BLACK+DECKER Portable Air Conditioner for Small Rooms (8,000 BTU)

The portable air conditioners in this list have more cooling power than the previously listed window air conditioners.

This is intentional.

Portable air conditioners are not as efficient as window air conditioners. So, to get the same amount of cold as a window air conditioner, a portable AC needs a bit more cooling capacity.

This BLACK+DECKER portable air conditioner (click here to view it on amazon) is my personal recommendation for small rooms.

It’s a great portable air conditioner in general. And the cooling capacity of 8,000 BTU is perfect for most small rooms. The air conditioner’s shape is well-rounded, so bumping into this air conditioner at night won’t hurt too much (yes, that’s a criterion!).

Technically, this portable air conditioner is not any better or worse than other well-built portable air conditioners (such as the next two recommendations).

I ranked this one as the best portable air conditioner for small spaces because it has the perfect cooling capacity, and it has a ton of great ratings! (over 40,000…)

You can’t go wrong with this one.

#5 SereneLife Portable Air Conditioner (8,000 BTU)

This SereneLife portable air conditioner (click here to view it on amazon) is my number two recommendation for small-room portable air conditioners.

This one works just as well as the previous portable AC. The only difference is really how it looks.

The technical details such as cooling capacity, power consumption or energy efficiency are about the same.

So, I’d suggest you have a look at both portable ACs and pick the one that you like better based on what suits better into your room.

#6 Whynter ARC-14S Portable AC (14,000 BTU)

The Whynter ARC-14S portable AC (click here to view it on amazon) is my all-time favorite portable air conditioner model.

Even though the 14,000 BTU are too powerful for small rooms, I just had to include it.

Here’s why:

The Whynter ARC-14S is a dual-hose air conditioner. Instead of one hose that blows air out of the window, this one has two hoses. And this makes a huge difference in terms of energy efficiency.

Dual-hose air conditioners use one hose to blow the extracted heat out of your room, and the other hose is for sucking in outdoor air which is to be cooled and blown into your room.

A single-hose AC can’t do that. Instead of sucking in outdoor air for cooling, it sucks in your indoor air… And that’s the air you just cooled.

So, single-hose ACs cool the air, and then they blow the same cooled air out of your room.

That’s why dual-hose portable air conditioners are just so much better.

I highly recommend getting this model if you have the extra money (it’s slightly more expensive).

The increased efficiency will pay off quickly!

To adapt the AC to your room’s small size, just lower the temperature settings.

#7 Hessaire Evaporative Cooler

Evaporative coolers are not real air conditioners. Air conditioners always have to blow extracted heat out of your room.

An evaporative cooler contains watered sponges and blows air over them. The evaporation absorbs heat and leaves cool air behind which is blown into the room.

I recommend this Hessaire Evaporative Cooler (click here to view it on amazon). It is powerful enough to cool down small rooms quickly.

To refill water, you can either refill manually, or you can connect to a tap or water tank for a continuous refill.

How much cooling capacity (in BTU) do small room air conditioners need?

A good estimate for most rooms is 20 BTU per square foot. So, here’s how much cooling capacity different small room sizes need:

Room sizeCooling capacity
100 sq. ft.2,000 BTU
150 sq. ft.3,000 BTU
200 sq. ft.4,000 BTU
250 sq. ft.5,000 BTU
300 sq. ft.6,000 BTU

All of the air conditioners recommended in this article were either 5,000 BTU or higher. So, you will definitely find one that suits your room size.

Small 100 square feet rooms need just 2,000 BTU of cooling capacity. That’s a lot less than even the smallest air conditioners provide.

If you have such a small room, you can also think about placing a larger 8,000 BTU air conditioner in the neighboring room and just leaving the door open.

This increases the effective to-be-cooled area and then you don’t have to worry about getting a small air conditioner specifically for your very small room.

Which air conditioner type is best for small rooms?

My personal favorite AC type are window air conditioners. But portable air conditioners are fine as well. Here’s why.

Window air conditioners

The best air conditioner type for small rooms is a window air conditioner. Window air conditioners are very efficient and they don’t take up any floor space in your small room since they are window-mounted.

Interestingly, window air conditioners come with even smaller cooling power (BTU) ratings than portable air conditioners.

The reason is probably that window air conditioners cool more efficiently and, therefore, can create a good cooling effect even with lower cooling capacity ratings.

Portable air conditioners

Portable air conditioners are also good for small rooms. However, they will consume more electricity than window air conditioners due to their bad efficiency.

I recommend getting a portable air conditioner over a window air conditioner only if you plan to use your portable air conditioner in other rooms as well.

In this case, portable air conditioners are easy to move around the house and they are great for portable cooling.

In small rooms, portable air conditioners will take up the floor space in front of your window. So, before buying one, check that you have enough space available.

Evaporative coolers

In general, I don’t recommend evaporative coolers. They are very energy efficient, but they are just not real air conditioners and you will always have to refill them. Also, you will have to deal with damp air and regularly vent your room.

The damp air is what makes you feel cooler since damp air sucks away heat from your body. So, evaporative coolers are (partially) not real cooling but just perceived cooling.

The only real advantage of evaporative coolers over air conditioners is that they don’t need any installation.

You don’t need to mount them to your window. You can just run them whenever you want.

So, they are more portable than portable air conditioners. 

Should you get a small or a big air conditioner for your small room?

Air conditioning a small room does not always make sense. While it keeps your air conditioner’s running cost low (because your AC has to cool only one small room), you will have to buy an entire air conditioner just to cover a small space.

The long-term running cost of small air conditioners is low, but the initial purchase is very high when you consider the small space you want to cover.

In general, larger air conditioners are not much more expensive than smaller ones. Getting a 10,000 BTU (or higher) model won’t cost you double what a 5,000 BTU AC costs.

So, the price per BTU is higher for small ACs.

Instead of air conditioning your small room only, you can get a larger air conditioner and cool the neighboring rooms and leave the door open. This leaves you with a fully air-conditioned living space while paying a similar initial price for the larger AC model.

Of course, this does not apply to everyone. If you are living in a one-room apartment or you live with roommates, then you usually don’t have any other choice than getting an air conditioner for your small room.

Why you should cool larger spaces instead (Mathematically explained)

You can’t really cool a small room effectively. The reason is the surface-area-to-volume ratio of small rooms.

The volume of a room determines the amount of cold air it can hold. The surface area of a room determines how much heat enters it.

Small rooms have small volumes. But this causes an interesting mathematical effect. A small room’s surface area (made up of walls, ceiling, and floor), is comparatively very large when compared to its volume.

In contrast, a larger room has a lower surface area to volume ratio.

Let’s consider different square rooms (for ease of computation) with a ceiling height of 9 feet and check their volumes and surface-area-to-volume ratio:

Floor area (in square feet)Surface area of ceiling, walls and floor (in square feet)Room volume (in cubic feet)Surface-area-to-volume ratio
100 sq. ft.560.00 sq. ft.900 cft0.622222
150 sq. ft.740.91 sq. ft.1350 cft0.548821
200 sq. ft.909.12 sq. ft.1800 cft0.505065
250 sq. ft.1069.21 sq. ft.2250 cft0.475204
300 sq. ft.1223.54 sq. ft.2700 cft0.453162
350 sq. ft.1373.50 sq. ft.3150 cft0.436031
400 sq. ft.1520.00 sq. ft.3600 cft0.422222
450 sq. ft.1663.68 sq. ft.4050 cft0.410784
500 sq. ft.1804.98 sq. ft.4500 cft0.401108
surface-area-to-volume ratio of rooms

As you can see in the table, small rooms have a higher surface-area-to-volume ratio than large rooms.

This means in a small room there is only a little volume of air to cool, but a lot of surface area through which heat can enter your room.

This means to keep a small room cool, you have to continuously run air conditioning. Because a relatively large amount of heat is constantly entering your room through the walls.

This makes all non-air conditioning cooling methods obsolete. Venting your room, for example, will only cause your room to heat up quickly again.

The mathematics of surface-to-volume ratio are a strong indicator that cooling larger spaces and keeping doors open is much more cost-effective than cooling just the small room you’re in.

Here’s a list of the most powerful air conditioners (for larger rooms) in case I convinced you.


Here’s some decision help for you:

If you want to cool your small room cost-effectively, then get a window air conditioner.

Window air conditioners are too hard to set up for you or you want to be able to move your air conditioner around the house? Then, get a portable air conditioner.

Only ever get an evaporative cooler if you really can’t install anything to your window. Evaporative coolers are a trade-off and won’t work as well as real air conditioners.

In case your small room connects to a larger room that you spend your time in as well, get a larger window or portable AC and cool the large room instead. Large rooms can hold the cold a lot better than cold rooms due to their lower surface-area-to-volume ratio.