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What Size Portable AC Do You Need?

Portable ACs are the perfect portable cooling solution for areas where installing standard air conditioning systems may be cost-prohibitive, impractical, or impossible. This is especially true in settings such as apartment buildings or server rooms located within an interior of a building. Moreover, portable air conditioners are compact, easy to maneuver, do not require permanent installation, and because they're most often used to cool specific areas as opposed to entire homes or buildings, they are quite energy-efficient as well.

How Do They Work?

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With regards to design, portable air conditioners are simple cooling devices. The box-like housing of the unit holds the cold and hot sides of the air conditioner in one while an exhaust hose expels heat. Water is condensed out of the air which is then collected in an internal drain bucket or through a drain hose. Furthermore, some portable ACs even utilize advanced evaporative technology and thus produce very little or no water at all.

In addition to the above benefits, portable air conditioners are also multi-functional and offer more than just cooling. The refrigeration cycle utilized by these portable coolers dehumidify moisture from the air, and some units even come with built-in heaters and air purifiers.

How Do I Size One?

Nonetheless, when it comes to choosing a portable AC , one of the most common mistakes consumers make is incorrectly sizing their unit. Portable air conditioners are sized according to BTUs, which stands for British Thermal Units. A BTU is a unit of energy that is commonly used in the power, steam generation, and heating and air conditioning industries. Generally speaking, a portable air conditioner's BTU rating describes its power and cooling capacity. Naturally, the higher the BTUs, the stronger the portable AC. Portable air conditioners have cooling capacities that usually range from 5,000 BTUs to as high as 30,000 BTUs, and the size needed to cool a room will depend on the area being cooled.  Thus, an incorrectly sized portable AC with insufficient or excess BTUs will result in inefficient cooling.

icon_bulb-blue-1 Portable Air Conditioner Buying Tip:
If a portable AC has a higher BTU rating than needed, the unit will cycle off too quickly and will not properly remove humidity from the air. On the other hand, an insufficient number of BTUs will not adequately cool a room.
Before you decide on your area's BTU requirements, first compile the following information:
  1. Calculate your room's square footage by multiplying its length by its width.
  2. Verify the size of the window opening for venting.
  3. Check the plug type and electrical requirements of your room.

After these have been verified, it is then time to determine your BTU requirements. Simply look to the chart below:

Portable Air Conditioner Sizing Chart

Square Footage

Required BTUs

Recommended Air Conditioner

100 - 200

7,000 - 8,000

American Comfort ACW200C

150 - 250

8,000 - 10,000

NewAir AC-10100H

250 - 350

10,000 - 11,000

NewAir AC-12100E

350 - 525

12,000 -16,000

Soleus LX-140

For example, if your room measures 20 feet by 20 feet, your calculations will look like so:

20' x 20' = 400 square feet

 400 square feet = at least 12,000 BTUs

As such, if your room measures 400 square feet, you will need a portable air conditioner that offers 12,000 BTUs of cooling. However, please note that the figures in the chart above are estimates based on average room conditions in a moderate climate. Some exceptions may also apply, and these are listed below:

  • For second story homes or especially sunny areas, add the BTU amount by 10%

  • For shaded areas, reduce the BTUs by 10%

  • For each additional person over two persons in a room, add 600 BTUs

  • To cool a kitchen, add 4,000 BTUs

icon_bulb-blue-1 Portable Air Conditioner Buying Tip:
See our portable AC sizing page for help on sizing a portable air conditioner by room size and type .

Portable Cooling Guide Main Page
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