Best Mini Split System Size For Cooling Your Room

Are you interested in purchasing a mini split system air conditioner? Regardless whether you are just supplementing your central air conditioner to reduce the utility bill, or if you are buying a mini split unit as a main air conditioner, you are looking to save money in the long run with a split AC system. But you must first determine the size of your unit so you will not be disappointed. You will save even more money when purchasing the mini split when picking the size right.

The principal elements that determine the size of your split type air conditioner are: Square footage of the room, Number of people inhabiting the space, Sunny windows, Shaded windows, Doors, and any major heat producers in the room such as kitchen appliances. Let's see how the formula works.

The basic formula

If you do nothing else, keep in mind that "one ton" or 12,000 BTU/h of air conditioning output will cool a 400 square feet room of normal height. BTU is the cooling capacity of the mini split system that will be given in the brochure, online, and in the box. BTU stands for British Thermal Unit.

The advanced formula

When you want to be more precise in your estimation use this formula: BTU = 35 x square footage. So the larger the floor plan, the bigger the split AC system capacity.

Additions to the advanced formula

1. When your room that you are cooling includes appliances that produce heat, add 4000 BTU to the total. This assumes a standard size kitchen with a refrigerator, a stove, and an oven.


2. When you have windows that are sunny, add 1000 BTU to the total estimate for each 10 square feet of sunny windows.


3. When you have windows that are in shade, add 500 BTU for each 10 square feet of shaded windows.


4. Add 1000 BTU for each door leading to an unconditioned space as well.


5. Finally, for each person over two that occupies the space on a regular basis, add 1000 BTU to the formula.

When you add all the components together, you will get an estimate of how powerful a mini split unit you need to be able to cool your room down properly, yet keep it small and less expensive to purchase at the same time.