Smart AC Buying Guide: Will it Work?

This post is the first in a three-part series that walks you through the important considerations when buying a new smart window air conditioner. If you are trading up, a first time buyer, or refreshing your knowledge for a future purchase, this post is for you. I will cover all the major considerations so you can get exactly what you want! Stay tuned for the upcoming posts as well.

In this post I will cover:
  • The Window
  • Cooling Capacity

The Window

The reason the window is so important is because it will change the options available to you. Not all window A/C units fit in all window styles and sizes. So, go check your window style and dimensions and get that written down so that as you shop, you can make sure the units you like will fit in your window. Here are some common styles:
  • Single Hung
  • Double Hung
  • Slider
  • Casement
  • Awning
  • Hopper
  • Tilt and Turn
Remember, the style and size are important.

Cooling Capacity

Since the goal is to control the temperature in a room, the cooling capacity is likely the most important consideration when buying an air conditioner. The amount of energy an air conditioner applies to cool the room is called BTU or British Thermal Units. To figure out what hourly rating you need go get a tape measure (right now!) and measure the space you want to keep cool. Now multiply the length and width of the room and use the table below to determine the minimum BTU rating.

Square FeetCapacity in BTU
100-1505,000 BTU
150-2506,000 BTU
250-3007,000 BTU
300-3508,000 BTU
350-4009,000 BTU
400-45010,000 BTU
450-50011,000 BTU
500-55012,000 BTU

You may need to adjust the BTU guidance in the table for the following sorts of situations:

  • A room that get full sun: Add 10%
  • The ceiling is higher than 8 feet: Add 10%
  • The room is shaded all day: Decrease 10%
  • The room is a kitchen: Add 4,000 BTU (cooking adds heat!)
You may also need a larger unit if the room regularly has more than 2 people in it... humans add heat to a room, too.

Note the minimum BTU rating you need and keep reading.


There you have it. These are the most important considerations when choosing a window air conditioner since if the unit does not fit the window and is not powerful enough, there is no way you will like it. Every situation and person are different so there may be other make or break considerations as well. While you shop, be sure to check out the Smart Window A/C Unit invented by Dr Garthen Leslie.

Check out the rest of the series here: