How Big of an AC Unit Do I Need?

How Big of an AC Unit Do I Need?


When it comes to air conditioners, it’s important to have a properly sized air conditioner. If you have an air conditioner that is too large for the room, it’s going to shut off early and not have enough time to dehumidify and remove the moisture necessary, leaving you with a cold and clammy environment. On the other hand, if the air conditioner is too small for the environment that you’re cooling, then the air conditioner will continually run, never cooling the room and never dehumidifying the room properly. Plus, it will cost you more energy. 


So how do we find the right BTU size air conditioner for your room?


British Thermal Unit is a form of measurement that measures energy. With these, it can help us know how big our AC should be. 


Determining the proper BTU Size: Simply measure the square footage of the room.


  • Length is multiplied by the width of the room and this will give you your square footage.
  • If it’s on the main floor, you multiply the square footage of the room by 30.
  • If it’s on the second floor or kitchen area, you multiply the square footage of the room by 40
  • If your ceiling is above 8 feet, then add 1000 BTU for each foot. 
  • We also need to consider the number of people in the room, for each person over the first two individuals, add 600 BTU


Example: The room is 15 x 20 square footage, located on the 1st floor, has 10 feet tall ceiling, and has only 1 occupant.


  • 15 (Length) x 20 (width) = 300 
  • 300 x 30 = 9,000 BTU
  • 9,000 + 2,000 = 11,000 BTU
  • Since there is only one occupant, we don’t need to add more BTU. The total is 11,000 BTU


If the AC doesn’t have any British Thermal Unit Specified on, rather a Ton, always remember that 1 Ton is equal to 12,000 BTU.


Some factors that are needed to be looked at are:


  • The type of the house
  • Type of windows and doors of the house
  • The orientation of the house
  • Trees that covering the house
  • Insulation levels in the house 


Another thing that homeowners would do is to always choose the big ones without considering some factors first. So before replacing your AC always consider these things first: 


  • The system could be low on refrigerant
  • The evaporator coil could be clogged,
  • The filter could be dirty
  • The ducts that lead to each room in your house could be damaged or crushed


These are the factors that could lead someone to think that their AC is undersized and should get a bigger one. But the bigger is not always the better. 


Your air ducts are sized for the size system you have now and if you get a bigger system, you can affect the static pressure in the system. Static pressure is like the blood pressure in your body. Just like if your heart’s too big for your body, it could cause complications to your body and it’s the same with the static pressure of your HVAC system. The bigger air conditioner and its compressor won’t be able to operate under the same comfortable conditions as it would if it was properly sized. And this will lead to early system failures if your new HVAC system. 


So, always calculate and consider these factors before deciding to buy a new one or replacing your old one. 

Your Local Huntington Beach HVAC Technician

Qualified Technicians

Experienced Air Conditioning Professionals that will do the work on your behalf, to make your home a little bit better.

Affordable Prices

We think that good air quality is something everyone should be able to afford.

Top Quality Service

Our HVAC Technicians are fully determined to provide the best possible service and to make you happy with the result.

Let's talk about your project

Experienced HVAC professionals are on standby and ready to answer all your questions. Don’t hesitate to get in touch! Call the number below.