What Size Portable Air Conditioner for Outdoor Use?

The size of the area you want to cool, how much it’s enclosed and how well it’s insulated help determine the size of portable air conditioner you’ll need.

How to Measure the Size of a Portable Air Conditioner

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”.

The needs for outdoor cooling can be dramatically different than for indoor cooling because of the wider variations in insulation and the degree and outdoor area is enclosed.

The chart below can help you get a general estimate of the “size” portable air conditioner you’ll need to cool a certain sized area.

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, especially with the wide variety of outdoor spaces and conditions.

100 – 1509.3 – 14.05,000
150 – 25014.0 – 23.36,000
250 – 30023.3 – 27.97,000
300 – 35027.9 – 32.58,000
350 – 40032.5 – 37.29,000
400 – 45037.2 – 41.810,000
450 – 55041.8 – 51.112,000 (1 TON)
550 – 70051.1 – 65.014,000
700 – 1,00065.0 – 92.918,000
1,000 – 1,20092.9 – 111.521,000
1,200 – 1,400111.5 – 130.123,000
1,400 – 1,500130.1 – 139.424,000 (2 TONS)
1,500 – 2,000139.4 – 185.830,000
2,000 – 2,500185.8 – 232.334,000
Area sizes and suggested BTUs to cool them. Actual numbers vary based on climate and conditions of the area to be cooled.

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 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. Mobile air conditioners well over 100 tons are available.

What affects the size of the portable air conditioner you’ll need?

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 insulated glass or vinyl panels would maintain the cool temperature better than a tent with canvas or mesh panels that would allow more of the cool air to escape. A tent with mesh panels might be better suited to a swamp cooler or fan. 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.

The best advice for choosing a portable air conditioner

When you purchase or rent a portable air conditioner, connect with a sales or rental consultant about 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 and set up for your needs. Especially for areas with little insulation, or for larger and mobile units, this service is invaluable.

Other Outdoor Cooling Methods

If you have a more open outdoor area that needs cooling, consider outdoor fans, misting systems, or misting fans which combine misting systems and outdoor fans into a single unit.

Swamp coolers (desert coolers) use a similar technology as misting systems (evaporation cooling), but in a contained unit. They are sometimes called air conditioners, but use a different technology than true air conditioners.

Outdoor shades are a nearly universal solution that combine well with every other cooling option.

Take a look at our comparison page to learn which outdoor cooling solutions may be best for you.