When it comes to buying air conditioners, people tend to focus on brand and type. They rarely give a second thought to the size of the air conditioner and whether it’s compatible to their home. An air conditioner that’s too small won’t be able to cool your loft adequately and an air conditioner that’s too sizable will leave excess humidity in the household while consuming a lot of energy, however calculating and choosing the correct size air conditioner is not actually difficult. All you need to do is some basic math. Using a tape measure, carefully measure the length and breadth of the room and multiply the two figures to calculate the square footage. This calculation is essential if you are going to make the appropriate decision on the air conditioner’s size. To make things easier in measuring the entire home, check your household tax statement to find your home’s overall square footage. You don’t need to take unused rooms or the basement into consideration when determining the final figure. Next, you should find out the cooling capacity required for your loft or room. British Thermal Units, or BTUs, are used for finding the cooling capacity of individual air conditioner units or central air conditioners. The U.S, however department of Energy has a convenient table to find the ideal air conditioner component size. For example, if you have a 1500 square foot home, the table indicates that 30,000 air conditioner BTUs are required. In the end, the brand and type of air conditioner are entirely pressing when making a purchasing decision. But don’t forget about the size and cooling capacity as well.