Cooling a 600-square-foot room requires an air conditioner with a cooling capacity of 14,000 BTUs. Choosing a unit that is too large or small for the space results in inefficient cooling.
Certain factors can change the capacity needed for cooling a specific space. For example, if a room is heavily shaded, the necessary BTU capacity can be reduced by 10 percent. Capacity should be increased by 10 percent for sunny rooms. For rooms that are regularly occupied by more than two people, add 600 BTUs per additional person. If the air conditioner is used in a kitchen, an additional 4,000 BTUs are required.