BTU Calculator for a 800 sq ft Room
A 800 sq ft room is 800 sq ft. Estimate the cooling BTU and the right AC size here, with climate and sun adjustments.
Runs locally in your browser — no upload, no trackingTry: Room area=800, Ceiling height=8, People usually in room=1, Room type=living, Sun exposure=avg, Insulation quality=avg, Climate zone (1–5)=3 → 16,000 BTU, 1.33 ton, 14,000–15,000 BTU, 28,000 BTU
How to use
A 800 sq ft room is 800 square feet. At the common rule of 20 BTU per square foot, the base cooling load is about 16,000 BTU before people, sun and climate are added. Eight hundred square feet is a small apartment or large open floor plan. Expect 1.5 tons (18,000 BTU) of cooling for central or mini-split systems. Use the calculator to fold in your real ceiling height, insulation and climate zone.
FAQ
What size AC for a 800 sq ft room?
Start from about 16,000 BTU and adjust upward for sunny windows, poor insulation or a hot climate, and downward for a shaded, tight room. Most 800 sq ft rooms land near a 5,000–12,000 BTU unit depending on those factors.