So how do you know which size air conditioner you need given the many different sizes available? It depends on the size of the room or rooms you are trying to cool. To start you need to measure the area that needs to be cooled and this will give you a good idea of the correct size air conditioner you will need. If you are looking for an air conditioner that will cool your entire house then please call us as there are many other factors needed to calculate this.



To calculate the size you need to multiply the length times the width of the room or rooms you are trying to cool. When trying to cool two adjacent areas determine each space separately and add the totals together. Then refer to our chart to the right to see how many BTU’s your air conditioner needs in order to cool the room(s) properly.

Example 1: You want to cool just one room that is 10′ long and 12′ wide.

10 X 12 = 120

By looking at our chart you would need an air conditioner with 5,000 BTU’s to cool this room of 120 sq. ft.

Example 2: You want to cool two adjacent rooms. Room #1 is 10′ long and 11′ feet and Room #2 is 8′ wide and 10′ long.

Room #1: 10 X 11 = 110
Room #2: 8 X 10 = 80

Total of both rooms is 190. You would need an air conditioner with 6,000 BTU’s to cool these rooms.

Once you have determined the number of BTUs that will most efficiently cool your rooms, you need to make adjustments based on other factors as well:

  • If the room is heavily shaded then reduce BTU’s by 10%
  • If the room is in a very sunny location then increase BTU’s by 10%
  • If more than two people are usually in the room(s), then add 600 BTUs for each additional person
  • If this is to cool a kitchen area then you need to add 4,000 BTUs

Common Room Sizes Are:

8 X 10 = 80 | 5,000 BTU’s Needed
9 X 10 = 90 | 5,000
10 X 12 = 120 | 5,000
11 X 13 = 143 | 5,000
12 X 12 = 144 | 5,000
12 X 14 = 168 | 6,000
13 X 19 = 247 | 6,000-7,000
14 X 18 = 252 | 7,000
16 X 20 = 320 | 8,000

While you can calculate the square footage on your own, one of our trained air conditioning professionals may be the better choice to perform a BTU calculation on your home. Give us a call and we will be more than happy to help you get the correct air conditioner you need.