Air conditioners are among the top purchases in the summer seasons, especially in countries in high hot zones. While purchasing air conditioners, like at the time of purchasing other products, consumers are often overwhelmed by the choices available. They have to make a wise decision to purchase the most suitable product for their homes and offices. In case of air conditioning units, the most important aspect is the size of the unit. Basically, there are two types of air conditioners, window AC and Split AC. No matter what kind of air conditioner you are looking at, the size is an important aspect that you have to consider. Only the proper size of the AC will make your room cool as it should be. Air conditioners are available in different sizes to suit the requirements of different consumers. The right size of the air conditioner cools the required area of your home with most efficiency. You can easily find the size of the unit by measuring the size of your room. How to calculate the size of Air conditioning unit Calculating it is pretty simple; measure the length and width of the room and multiply them to have the area of the room. Now to have the practical number that will help you purchase your AC, multiply the number obtained with 25 BTU. The number obtained is the right size of air conditioner you need for that room and it will provide you with enough cooling to keep you cool and in any season be it hot, sunny or rainy day. Let us understand this by having an example. Let us say your room is 15 feet long and 12 feet wide and the area comes to be 180 sq. feet. Now multiply 18 sq. ft. by 25 BTU per square foot. It comes to be 180 x 25 = 4500 BTU which is the cooling capacity and the minimum BTU air conditioner you should buy. Small or big ; Make the decision You may ask if you can do with a smaller unit. In that case, you will have to continuously run your AC to just trying to keep the room cool. It will have two disadvantages; you will not able to cool the room as required and add to this you will end up paying more electricity bills. On the other hand, installing a larger AC than required would overkill your excitement and your bills. A too large AC would cool the room too quickly and you may not feel the desire to keep that running. However, AC not only cools the room but also removes humidity. That means, an air conditioner too large will not offer you the efficiency you are looking for. A smaller size AC for a bigger room will not cool it to the point required by you and a larger sized AC for a smaller room will consume extra energy unnecessarily and increase your energy bills. Thus, the first thing you should determine is the right size of the air conditioner.