Portable Air Conditioners and BTUs - What You Need to Know

Why portable AC?

AC-14100H-Image9In areas where installing a central air conditioning unit is:

  • Impractical
  • Impossible
  • Cost-prohibitive

a mobile air conditioner can help you stay cool and comfortable. Some of the greatest advantages of a portable air conditioner is its maneuverability and simple installation. Although portable ACs still need to be vented, permanent installation isn't required, and most units have caster wheels which allow you to move the unit from room to room. They are also a cost-effective alternative to central air conditioning systems because they allow you to cool specific areas instead of an entire home.

How do they work?

Portable air conditioners are relatively simple appliances. A box-like configuration holds both the cold and hot sides of the air conditioner in one and an exhaust hose expels heat. Water is condensed out of the air, and most portable units collect this water in an internal drain bucket or through a drain hose. As well, some models use evaporative technology and produce very little to no water at all.

Many models available on the market are also multi-functional in that they offer more than just portable cooling. In fact, some units include built-in dehumidifiers, air purifiers, and even heaters - making them truly versatile and not just suitable for the summer heat.

Portable AC BTU ratings

However, many consumers often overlook certain factors when purchasing a portable air conditioner and one of the most common mistakes is not paying attention to a portable AC's BTU rating.

KY-34 image 1BTU stands for British Thermal Unit, and it is a unit of energy used in the power, steam generation, and heating and air conditioning industries. Essentially, an air conditioner's BTU rating describes its power and cooling capacity and the higher the BTU value, the stronger the air conditioner.

Cooling capacities usually range from 5,000 BTUs to as high as 30,000 BTUs, and the size you need will depend on the area being cooled. If you choose a model with the wrong BTU value, your cooling efficiency can be affected.

An air conditioner with a higher BTU rating than the corresponding room size will cycle off too quickly, and the air conditioner will not properly remove the humidity from the air.

On the other hand, if a mobile air conditioner has a lower BTU rating than the required room size, the unit will not adequately cool the room.

Follow the steps below to calculate your room's square footage and find out the BTUs you need to properly cool your area from the preceding chart:

  1. Measure your room dimensions by multiplying length by width.
  2. Verify the size of your window opening.
  3. Check the plug type and electrical requirements of your room.
  4. Find the recommended BTU measurements from the chart below.

For example, if your room measures 18 feet by 25 feet, your calculations would look like this:

18' x 25' = 450 square feet
450 square feet = portable air conditioner with 10,000 BTUs

Room Size Recommended BTUs
150 square feet up to 5,400 BTUs
200 square feet 6,000 BTUs
340 square feet 8,000 BTUs
400 square feet 9,000 BTUs
450 square feet 10,000 BTUs
550 square feet 12,000 BTUs
750 square feet 14,500 BTUs
850 square feet 16,000 BTUs
1,000 square feet 18,000 BTUs
1,400 square feet 24,000 BTUs
1,520 square feet 28,500 BTUs
1,600 square feet 32,000 BTUs


newair-ac-10100e-10Alternatively, to get a quick ballpark figure of the BTUs you will need for your room, multiply the square footage of the room by 35 to get a very rough estimate.

Please note that the figures in the chart above are estimates based on average room conditions in a moderate climate; therefore, pay attention to the following exceptions if they apply to your room or home:

      • For sunny areas or second story and higher homes, add BTUs by 10%
      • For shaded areas, reduce the BTUs by 10%
      • For each additional person over two persons in a room, add 600 BTUs
      • For kitchen cooling, add 4,000 BTUs

Once you've found your BTU requirement, click here to visit our selection of portable air conditioners to find the perfect model for your needs. Need help calculating your room size? Call our cooling experts for advice and product recommendations. We're always here to help.

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The Green Guide to Portable AC
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