What size portable AC do I need for my room?

As a rough guide using SACC ratings: under 250 sq ft needs ~6,000–8,000 SACC BTU, 300–450 sq ft needs ~10,000 SACC BTU, and 500–600 sq ft needs ~12,000 SACC BTU. High ceilings, sun exposure, and kitchens push you up a tier. Oversizing isn't free — it shortens cycles and worsens dehumidification.