How to choose an air conditioner

Step 1: Determine your square footage 

In order to determine what BTU capacity you need (see chart below) you need to measure your room. Here’s how:
• For square or rectangular rooms, multiply the length by the width.
• For triangular areas, multiply the length by the width and divide by two.
• For unconventional room shapes, divide the room into triangles and squares and measure areas to get total square footage.

Step 2: Make any adjustments for room circumstances

There are a few rules that can be helpful for adjusting your idea BTU rating:
• For well-shaded rooms, reduce capacity by 10 percent or opt for the next smaller unit.
• For very sunny rooms, increase capacity by 10 percent or opt for the next larger unit.
• Add 600 BTUs for each additional person that regularly uses a room.
• For kitchens, add 4,000 BTUs to your desired capacity or opt for the next larger unit.
Finally, consider where you’ll install the unit. If you’re setting an air conditioner up in the corner of a room, look for a unit that will send the airflow in the right direction. For portable air conditioners, the flexible exhaust hose allows placement of the unit at least 2 inches from the window or door.

Step 3: Pick the right air conditioner for you 

Now that you've figured out the capacity you need for your space, you can decide what type of air conditioner is right for you.

Portable air conditioners are easy to install but take up floor space. Window air conditioners are quieter, but not always permitted and require sliding windows that can allow for the size of the air conditioner. For window air conditioners, you'll want to measure your window to make sure a unit will fit.