Mini Split Sizing Calculator

A common starting rule is 20-30 BTU per square foot of conditioned space. A 400 sq ft room needs roughly 9,000-12,000 BTU. Adjust up for high ceilings, heavy sun, poor insulation, or hot/cold climates, then confirm with an installer's Manual J load calculation.

Yes. An oversized unit cools too fast, short-cycles, removes less humidity, and wears out sooner. Matching capacity to the room is more comfortable and more efficient than going big.