Site Visits and Estimates

The first step in choosing a room air-conditioner is measuring your space to calculate its square footage.

Formula: Length x Width = Square Footage (sq. ft)

The table below shows a more accurate BTU estimate based on the square footage to be cooled.

Area To Be Cooled (square feet) Capacity Needed (BTUs per hour)
100 up to 150 5,000 BTUs
150 up to 250 6,000 BTUs
250 up to 300 7,000 BTUs
300 up to 350 8,000 BTUs
350 up to 400 9,000 BTUs
400 up to 450 10,000 BTUs
450 up to 550 12,000 BTUs
550 up to 700 14,000 BTUs
700 up to 1,000 18,000 BTUs
1,000 up to 1,200 21,000 BTUs
1,200 up to 1,400 23,000 BTUs
1,400 up to 1,500 24,000 BTUs
1,500 up to 2,000 30,000 BTUs
2,000 up to 2,500 34,000 BTUs


Determining More Accurate BTU Estimates
To determine the most accurate BTU estimate, you should also consider these factors:

  • Ceiling Height
    • The above estimates assume you have traditional 8-foot ceilings. If your ceilings measure higher than 8 feet, you’ll want to increase your BTU level.
  • Sunlight
    • If your room or space is sunny during the day, increase your BTUs by 10 percent.
  • Shade
    • If your room is shaded for most of the day, decrease your BTUs by 10 percent.
  • Number of Occupants
    • If more than 2 people will occupy your room or space regularly, you should add an additional 600 BTUs of cooling power for each person.
  • Kitchen:
    • If you are installing your window A/C unit in a kitchen, increase the BTU level by 4,000.

One of the most common mistakes in selecting a room air-conditioning unit is the purchase of an underpowered unit that will not properly cool the room. With the proper measurements and calculations, you will be able to determine the square footage of your room and make the wise choice for your next room A/C unit.


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