Posted by K-Star on Jun 26th 2020

What Air Conditioner Should I Buy? - Sizing Chart - KSTAR

What is your BTU requirement?

How many BTU do I need for my new mini split air conditioner? This is probably the first and most important consideration when purchasing a new air conditioner. You want to get a unit with a capacity as closely matched to your needs as possible. A unit that is not powerful enough will run constantly and will never properly cool the room. A unit that is too powerful will "short cycle," which means that it will cycle on and off over and over again, only remaining on for short periods of time. Short cycling is bad for the compressor, because it could substantially shorten the lifespan of the air conditioner, and the air conditioner will not dehumidify appropriately, so while the air in your room might be a comfortable temperature, there could be an uncomfortable level of humidity. The ideally sized unit will run at its maximum capacity on the few hottest days of the year and run somewhat under capacity at other times.

Sizing Chart

Here is a helpful reference chart when you are looking to buy a new air conditioner.

Square Feet BTU's Required
250 - 300         7,000
300 - 350 8,000
350 - 450 10,000
450 - 650 12,000
650 - 850 13,000
850 - 1,100 18,000
1,100 - 1,400 24,000
1,400 - 1,800 25,000
1,800 - 2,500 29,000


  • Add BTU by 10% for sunny areas
  • Add BTU by 10% for second story (or higher) rooms
  • Add 4,000 BTU if used for cooling kitchen
  • Add 600 BTU for each additional person (expected to use the room) over 2 persons
  • For commercial applications (shops, office, etc.): 400 sq. ft. per 12,000 BTU
  • For computer rooms and telephone servers: 250 sq. ft. per 12,000 BTU

How We Can Help

At K-STAR, we have just high quality, energy efficient, DC inverter mini split air conditioners with BTU's of 9000, 12000, 18000, and 24000. We are happy to help you choose your new air conditioner. If you have any questions regarding our products, please feel free to  contact us.

*This guide should be used as a rule of thumb and not substituted for proper load calculation*