How to Choose a Portable Air Conditioner for Your Home

Guide to Portable AC Cooling Size (BTUs) for Rooms

When choosing a portable air conditioner, it’s important to buy one with the right cooling (BTU) rating for the size of your space. While it may seem that bigger is better, that’s not true with AC units, since a unit that’s too large for the space will cycle on and off too quickly to cool and dehumidify the air properly.

Portable AC unit
Portable AC unit

In general, portable AC units need to have more cooling power (BTUs) than window units. Follow manufacturer’s recommendations, but here’s a general guide for portable units:

  • 5,000-7,000 BTUs: Rooms up to 150 square feet
  • 8,000-9,000 BTUs: Rooms 150-250 square feet
  • 10,000 BTUs: Rooms 250-350 square feet
  • 12,000 BTUs: Rooms 350-450 square feet
  • 14,000 BTUs: Rooms 450-550 square feet

You should also:

  • Add 2,000 to 4,000 more BTUs if the portable AC unit will be in a kitchen or a room with heat generating appliances or tools.
  • Choose a higher BTU rated portable AC unit if you live in an exceptionally hot climate, or if more than two people will be living in the room.
  • Increase BTUs 10% for sunny rooms with lots of windows or poorly insulated spaces.
  • Decrease BTUs by 10% for deeply shaded or naturally cool rooms.


  1. There are two different BTU ratings on each unit. Of course the higher of the two is the one that’s touted loudly on the packaging and the lower of the two is in smaller print a ways down. What I want to know is why are the two numbers so far apart ? Mine says 8000 BTU / 5500 BTU. Is it a “peak” vs “average” or “continuous” like with generators ? Or something else ?


Please enter your comment!
Please enter your name here