Find the Right Portable Air Conditioner
Size For Your Outdoor Space

A large tent cooled by a portable air conditioner

To find the right portable air conditioner size you'll need to know the approximate size of the area you want to cool. This will tell you about how much cooling capacity you'll need from a portable air conditioner.

If you have more than one area that needs to be cooled, consider whether one unit can be positioned to cool both areas, or if you'll need multiple units. One large unit can often be set up to cool several small areas at the same time.

BTUs (British Thermal Units) are a common way to measure the cooling capacity of air conditioners. It's often simpler to call it the "size" of the air conditioner, instead of "how many BTUs" or "how much cooling capacity".

Follow the chart here only to get a general estimate of the "size" portable air conditioner you'll need to cool a certain sized area.

Note that different manufacturers will have different charts with different recommendations of BTUs for different sized areas. This is because the best size for your area depends on a lot of different factors. Varying charts base their recommendations on different criteria. This emphasizes the fact that your cooling needs are fairly unique.

Square Feet Square Meters BTUs per hour
100 to 150 9.3 to 14.0 5,000
150 to 250 14.0 to 23.3 6,000
250 to 300 23.3 to 27.9 7,000
300 to 350 27.9 to 32.5 8,000
350 to 400 32.5 to 37.2 9,000
400 to 450 37.2 to 41.8 10,000
450 to 550 41.8 to 51.1 12,000*
550 to 700 51.1 to 65.0 14,000
700 to 1,000 65.0 to 92.9 18,000
1,000 to 1,200 92.9 to 111.5 21,000
1,200 to 1,400 111.5 to 130.1 23,000
1,400 to 1,500 130.1 to 139.4 24,000*
1,500 to 2,000 139.4 to 185.8 30,000
2,000 to 2,500 185.8 to 232.3 34,000

Some variables to consider:

  • Depending on outdoor air temperature and humidity, you may need to increase the BTUs by up to 40%. It takes more BTUs to cool a hotter space than a cooler one.
  • If more than two people will regularly be in the space, add 600 BTUs per person. Bodies add warmth to an area and more BTUs will be needed to cool an area with more people in it.
  • Materials and insulation of the enclosed space will have a big effect on the efficiency of any portable air conditioner. For example, a tent with tightly woven canvas or nylon panels would maintain the cool temperature better than a tent with mesh panels that would allow more of the cool air to escape. A trailer might have more insulation in the walls than a shed, and would maintain the cool temperature better than the shed would. Allow more BTUs for areas with less insulation.
  • You can counter poor insulation somewhat by placing the unit closer to the spots that need the most cooling.

* In the world of air conditioning, multiples of 12,000 BTUs are commonly referred to as a "ton." This does not mean the air conditioner weighs 1 ton! A "1 ton" air conditioner may only weight 150 pounds / 68 kg.

A 12,000 BTU portable air conditioner is called a "1 ton air conditioner." A 24,000 BTU portable air conditioner is called a "2 ton" unit. A 36,000 BTU portable air conditioner is called a "3 ton" unit, etc. Sizes over 5 tons (60,000 BTU) are called "mobile" air conditioners.

If you're in doubt, when you purchase or rent a portable air conditioner, tell your sales or rental consultant the size of the area you'll be cooling, a description of the area (shed, tent, trailer, etc.), and how many people will be using it. This will help them advise you on the best sized unit for your needs.

Interested in learning even more?

Visit our other pages on using portable air conditioners outdoors:

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