|Area To Be Cooled (sq. ft.)||Capacity Needed(Btu/Hour)|
|100 to 150||5,000|
|150 to 250||6,000|
|250 to 300||7,000|
|300 to 350||8,000|
|350 to 400||9,000|
|400 to 450||10,000|
|450 to 550||12,000|
|550 to 700||14,000|
|700 to 1000||18,000|
|1,000 to 1,200||21,000|
|1,200 to 1,400||23,000|
|1,400 to 1,500||24,000|
|1,500 to 2,000||30,000|
Make adjustments for the following circumstances:
- If the room is heavily shaded, reduce capacity by 10%.
- If the room is very sunny, increase capacity by 10%.
- If more than two people regularly occupy the room, add 600 BTUs for each additional person.
- If the unit is used in a kitchen, increase capacity by 4,000 BTUs.
- Consider where you install the unit. If you are mounting an air conditioner near the corner of a room, look for a unit that can send the airflow in the right direction.
- For the purpose of this chart, rooms that are connected by permanently open entryways wider than five feet ought to be considered as one room and their square footage should be combined.
If you have a few extra minutes, the Association of Home Appliance Manufacturers has a more detailed worksheet on its Web site to help you determine the proper sizing.
 energystar.gov; http://www.energystar.gov/index.cfm?c=roomac.pr_properly_sized