1- Specify the suitable cooling capacity (in tons) of the air conditioner based on the size of the room. 2- If the lights in the room radiate a lot of heat, then you need extra cooling capacity. 3- If you are using heat-radiating appliances, such as a fridge or a stove, you should consider raising the capacity 4- If the room is facing east or west, extra capacity is needed due to exposure to sunlight during the day. 5- Consider the safety factor when coping with max load. Refer to engineers to determine the actual load. 6-A higher than-needed capacity will cool a room but will leave a damp & dew sense due to the high relative humidity 7-A units with a capacity less than needed will not function effectively during the hot days of summer.