Sizing Guide for a Mini Split Air Conditioner


To size your mini split air conditioner, the most important thing you need to know is the square footage of the room you’re looking to cool and/or heat. Each indoor unit will be capable of providing a set number of BTU’s of cooling and heating power. In order to size your mini split correctly, you will need to know the square footage of the room, and check it against our table.

For multi-zone systems, you will need individual air handlers for each room, with the specified BTU. Take the total BTU of the indoor heads, to establish the total outdoor capacity needed.

BTU Sizing Chart for Mini Split Systems

Check out our square footage and BTU comparison chart below. The following table is for individual zones, for a multi-zone, combine the total BTU’s needed to establish the overall BTU values of the system.

Area To Be Cooled Capacity Needed (BTUs Per Hour)
150 to 250 square feet 6,000 BTUs
250 to 300 square feet 7,000 BTUs
300 to 350 square feet 8,000 BTUs
350 to 400 square feet 9,000 BTUs
400 to 450 square feet 10,000 BTUs
450 to 550 square feet 12,000 BTUs
550 to 700 square feet 14,000 BTUs
700 to 1,000 square feet 18,000 BTUs
1,000 to 1,200 square feet 21,000 BTUs
1,200 to 1,400 square feet 23,000 BTUs
Up to 1,500 square feet 24,000 BTUs

Environmental Factors

Take into consideration any environmental conditions or external factors, including increased humidity, temperature, ceiling height, and/or additional heat sources. If any of these factors apply to you, you may want to consider increasing the BTU values to compensate for the environmental factors.

Environmental Condition % BTU Increase
Ceiling Height: If your ceilings are higher than 8 feet, you should increase your number of BTUs. 20%
Insulation: Poorly insulated areas require more power to cool. 30%
Climate: In areas with seasonal temperatures often exceeding 90 degrees F. 30%