Mini-Split Size Calculator

How It Works

Mini-split systems (also called ductless systems) deliver heating and cooling directly to individual rooms without ductwork. They are highly efficient because they avoid the 20 to 30 percent energy loss that occurs in typical duct systems. Mini-splits come in standard sizes: 9,000, 12,000, 18,000, 24,000, and 36,000 BTU. A 12,000 BTU unit (1 ton) typically handles 300 to 500 square feet depending on insulation and climate. Multi-zone systems use one outdoor unit connected to multiple indoor heads, each independently controlled. In very cold climates (below 5 degrees F), look for cold-climate mini-splits rated to operate down to -15 F or lower.