BTU 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, a portable air conditioner’s BTU rating describes its power and cooling capacity and the higher the BTU value, the stronger the system.
Cooling capacities usually range from 5,000 BTUs to as high as 32,000 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.
A portable 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.
Purchasing an air conditioner with the wrong BTU value for the space you’re cooling will result in problems with cooling efficiency, as an air conditioner that’s too powerful will cycle off too quickly and not properly dehumidify the room, and similarly, a unit with too low a BTU rating will not be adequately cool.
Follow the steps below to calculate your room’s square footage and find out the portable AC BTUs you need to properly cool your area from the preceding chart:
- Measure your room dimensions by multiplying the length by width.
- Verify the size of your window opening.
- Check the plug type and electrical requirements of your room.
- Find the recommended BTU measurements from the chart below.
To accurately find out how many BTUs your room needs, perform one of these two equations. Find the square footage of the room and multiply this number by 35 to get a general ballpark figure. Or, find the square footage of the room and find this number range in the following chart:
| 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 |
For example, if your room measures 18 feet by 25 feet, your portable ac BTU calculations would look like this:
- 18′ x 25′ = 450 square feet
- 450 square feet = portable air conditioner with 10,000 BTUs
Alternatively, 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 portable air conditioner BTU room size? Drop your comment below, and we’re always here to help.
