The size of the air conditioners doesn’t refer to the physical dimensions of the air conditioning unit.
Instead, it refers to its cooling capacity measured in British Thermal Units (BTUs).
Whether you intend to install a central air unit or a window air conditioning system, you will achieve optimum efficiency. Therefore, lower utility costs if you choose your air conditioning system based on the size of your home or the area your unit must cool. To choose what air conditioner size is appropriate for your household, first, you will need to calculate the size of your home’s areas that the air conditioner will serve in square feet. To calculate the size, multiply the width times the length of the area to be cooled. The total results are then multiplied by 25 BTU, which is a practical number. This size will allow ample cooling under any climatic condition, be it a rainy, hot, sunny, moist, or humid day. For instance, given a room that is 12 feet wide by 15 feet long, you will multiply the length by the width 12×15 to get 180 Square feet. The 180 square feet will then be multiplied by the 25 BTU per square foot to get you the minimum BTU air conditioning system you should install. This means 180 × 25 = 4,500 BTU cooling capacity is required for your space. While smaller BTU systems will run continuously to keep up with your temperature requirements, too many units will cool too quickly but won’t remove moisture from the air.