The Cooling Capacity of a Room AC

Small Air Conditioners

• Air conditioners rated at 5,000 to 5,600 BTUs are among the smallest room air conditioners available, according to Consumer Reports. These air conditioners have enough cooling capacity for rooms 100 to 350 square feet. Their small size makes them very easy to install and transfer from room to room if necessary. A disadvantage is that the limited cooling capacity may force the units to run at full blast on a hot day if the room size is more than 300 square feet.

Medium Air Conditioners

• Window units rated at 7,000 to 8,200 BTUs have enough capacity to cool rooms ranging in size from 250 to 400 square feet. These units are larger and bulkier than small air conditioners and are often more difficult to install. They are also more expensive than smaller units.

Large Air Conditioners

• The largest window units have powerful motors and cooling capacity, allowing them to cool rooms measuring up to 400 square feet. The tradeoff is that they are big, heavy and sometimes harder to install than small- or medium-sized air conditioners. Large air conditioners usually have BTU ratings ranging from 9,800 to 12,500 BTUs.

Considerations

• Cooling capacity is an important consideration when choosing a room air conditioner, but it isn’t necessary to choose a unit with the largest cooling capacity. An air conditioner that is too large for a room may start and stop repeatedly as it responds to thermostat settings. Bigger motors in the largest units allow the air conditioners to quickly cool a room and then shut off until the temperature rises. Then the units turn on again and the cycle continues. Avoid this by selecting a unit suited for your room.

Multiple Rooms

• Buy more than one window unit if you have multiple rooms to cool. It’s possible that a large room air conditioner could cool the living room and an adjoining kitchen of an efficiency apartment. But people seated closest to the air conditioner may find the air too cold, while those in the kitchen may find it not quite cold enough.