Calculating The Size Of Your Home AC Unit

What factors do contractors use in selecting house air conditioning units? In our current complete Remodeling Guide we will go over basic BTU calculations and some key points for your consideration.

Picking the right size air conditioner for your home is not as easy as it may seem. If you’re A/C unit is too small it will not be able cool correctly. If the unit is too large it will cool quickly but might not remove the humidity and thus leave you with a clammy feeling. A correctly sized A/C unit will remove both heat and humidity effectively. So before you contact your air conditioning supply house to order your unit you must properly understand your homes make up and the BTU’s you will need to cool it.

The BTU Calculator is based on square feet. Do you want to cool one room or would you like a whole house air conditioner? You will need to measure all the areas you are going to cool. This is pretty simple as it is just taking length x width of all areas and adding them together. If you have a room that is 10 x 12 you times those numbers together and it gives you 120 Sq. Ft. Calculate all the spaces you want to cool and add them together to give you the total Sq. Ft. Some people even plug in a size for the dog house air conditioning unit but you may not need that number. You then check the BTU chart and match it up to your Sq. Ft. number to size the unit needed to cool your area. So let’s say you have an area with a total square foot number of 1,200. With this number you would go with a 21,000 BTU system.

Square footage BTU size recommended
up to 150


150 up to 250


250 up to 300


300 up to 350


350 up to 400


400 up to 450


450 up to 550


550 up to 700


700 up to 1,000


1,000 up to 1,200


1,200 up to 1,400


1,400 up to 1,500


1,500 up to 2,000


But we are not done yet. To select the proper size A/C unit  for your home you will now need to figure in the extras that many miss. Things like how many people are usually in the home? People add heat and about 500 BTU’s more per person will be needed. How about kids running in and out and opening doors? Is the room sunny or shaded? A kitchen area can add a lot of BTU’s, how often is your oven on? What about your halls, did you measure all of them? Do you have large walk in closets? How large are your bathrooms are all the numbers added up correctly? All space you want cooled must be considered and added in. It can be easy to overlook some spots.

Also, don’t forget to look at how well insulated your home is, how high your ceilings are, How many widows do you have and how many hours a day does the sun directly hit your home?

Adding a whole house air conditioning system is a big job. While you could calculate simple square footage and BTU units needed on your own all the other calculations are much harder to fiqure in. Maybe one of our trained professionals would be a better choice to perform those calculations. There is a lot to consider and a free estimate is just that, free. Contact us here. We will be more than happy to help you get the correct A/C unit for your home.


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