The tradeoff in plain terms
ENERGY STAR describes mini-splits as ductless systems with indoor and outdoor units, so a single-zone setup usually maps one outdoor unit to one conditioned area while multi-zone systems add multiple indoor areas to one outdoor system. source ↗
A single-zone design can keep troubleshooting and rated-combination verification simpler because the indoor and outdoor pairing is narrower than a multi-zone equipment set. source ↗
A multi-zone design can reduce outdoor equipment count, but each indoor head still needs a load reason, refrigerant route, condensate route, control plan, and service path. source ↗ source ↗
How cost and performance trade off
Carrier explains that ductless installation cost varies with zones, efficiency, and complexity, so a quote comparison should break out equipment, indoor heads, line sets, electrical work, labor, and any finish repair. source ↗
AHRI-certified performance should be checked for the rated combination being considered, because multi-zone combinations can differ from single-zone ratings. source ↗
A load calculation matters before choosing zone count because rooms with different exposures or uses may not need the same capacity or operating schedule. source ↗