Keep in mind that although room size can significantly affect the BTU capacity you need, it is not the only factor at play. The environmental conditions and other external factors also play a huge role in determining the proper size of the mini-split you need.


The climate outside can affect the temperature indoors. Depending on whether you live on hotter or colder weather, your mini-split can be sized differently because of it. For instance, if you live in a place that has temperatures that frequently exceed 90 degrees Fahrenheit, then the BTU rating of the system you will purchase should increase by at least 30 percent.

Age And Insulation

The age of your home is a factor because newer homes typically have better insulation than older ones. This is due to the revised building codes. If you live in an older home that has poor insulation, then it requires more power to cool or heat. The BTU rating needs to be increased by at least 30 percent so that you can be comfortable. Whereas, if you have a new home with good insulation, then it requires fewer BTUs.

Ceiling Height

High ceilings affect the room size as they make the rooms larger. The standard ceiling height of most homes is eight feet. If your ceilings are higher than that, then it is recommended that you increase the BTU capacity of the mini-split you will purchase by at least 20 percent.

Other Factors

A few of the other factors that affect the BTU load calculation of your home include:

Windows And Doors:The number of windows and doors in the zone you are placing your mini-split in affects the BTU load as these are not insulated. Therefore, the cracks and small gaps in your doors and windows can leak air.

Direct Sunlight:Direct sunlight heats the room. Determine how much direct sunlight a room gets as it can affect the size of the mini-split the room needs.

Kitchen:If the room you want to put the mini-split unit in is a kitchen or a room close to the kitchen, then you might need a bigger sized mini-split so that you can adequately cool it. This is because kitchens are open spaces and have appliances that are sources of heat like ovens and stoves.

Number Of Occupants:People generate heat and can affect the size of the mini-split you need. Therefore, you need to take note of the usual number of occupants in the room you are putting the equipment in.

Lightbulbs:Lightbulbs also generate heat, and some types of bulbs create more heat than others. Therefore, the size of the unit is affected if a room has a lot of lightbulbs.

Floor Type:A floor that is carpeted is more insulated than one that is just hardwood. This could, therefore, affect the mini-split size that the room requires.