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Window AC vs Wall AC

Window ACs and Wall ACs are both popular choices for apartment owners in a similar position. These units work well for smaller apartments. Both window and wall ACs are more convenient than larger systems like central air.

But which is better for you? A window AC or a wall AC? 

What’s the difference  between window AC and wall AC

The difference between a window AC and a wall Ac is location. A wall AC is permanently mounted to your wall and a window AC fills the space in an open window. 

Window AC is a type of air conditioner that sits on your windowsill and is designed to cool a single room. Window ACs are popular in apartments because they don’t take up a lot of space and don’t need to connect to an outdoor unit.

Wall AC is an air conditioning unit with an internal unit that attaches to the wall and connects to an outdoor unit via a refrigerant line. Wall ACs are also designed to cool single rooms and small apartments. Wall ACs require more installation than window AC. 

Cooling Capacity

A wall AC has a slightly higher cooling capacity than a window AC. A typical window AC can produce 8,000 – 12,500 BTUs of cooling power while a wall AC can produce 9,000 – 14,000 BTUs.

The cooling power of air conditioners is measured in British Thermal Units (BTUs). One BTU is the amount of energy needed to change the temperature of one kilogram of water by a single degree Fahrenheit.

A window ACs 8,000 – 12,500 BTU capacity is enough to cool a space of between 300 – 550 square feet. That’s either enough for a single room or a small one-bedroom apartment.

You’ll find wall ACs that can cool the same spaces as window ACs. The only difference is that there are slightly more options in the 12,000 – 14,000 BTU range when it comes to wall ACs. 


A window AC is considerably more affordable than a wall AC. Window ACs cost $200 – $600 but you should expect to pay as much as $4,000 to get a wall AC installed.

The installation costs are the primary difference. A window AC just sits on your windowsill and you can complete the installation yourself in just half an hour.

Installing a wall AC involves cutting a hole in the wall to connect the internal unit to its external counterpart. Also, the wall AC needs to be integrated with your home’s wiring. 

You’ll need to pay a professional to install a wall AC and it’ll cost you.

Window ACs and wall ACs cost the same amount of money to run per hour, around $0.12 – $0.18. Those rates translate to $2.80 – $4.37 for a full day or $32.76 – $37.26 to run either unit for 6 hours a day for a whole month. 

That’s at typical energy rates in the US of $0.13 per kilowatt of power. Energy prices in the US are much higher than normal at the moment – around $0.23 per kilowatt of power.

At current rates, expect to pay $0.21 – $0.32 per hour, $4.97 – $7.73 for 24 hours, and $37.26 – $57.96 for 6 hours a day for a month. 

Energy efficiency

Wall ACs are generally less energy efficient than window ACs. A typical Wall AC has an EER (Energy Efficiency Rating) of 9 – 12 while a normal window AC has an EER of 10 – 13.

An air conditioner’s EER is a measure of how much power it wastes in the cooling process. You can calculate the EER by dividing a unit’s cooling capacity in BTUs by its energy consumption in watts. For example, a 12,000 BTU AC unit with a wattage of 1,100 would have an EER of 10.9. 

A higher EER indicates greater energy efficiency.

Should I buy a window AC or a wall AC?

You should buy a window AC over a wall AC provided you have a suitable window. Window AC and wall AC units are basically identical in terms of cooling power and window ACs are more efficient than wall ACs.

But the main reason you should buy a window AC rather than a wall AC is the massive difference in price. While running costs are the same, you’ll need to pay several thousand dollars more to get a wall AC installed.