BTU Calculator for a 15×15 Room
A 15×15 room is 225 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=225, Ceiling height=8, People usually in room=1, Room type=living, Sun exposure=avg, Insulation quality=avg, Climate zone (1–5)=3 → 4,500 BTU, 0.38 ton, 5,000 BTU window unit, 8,000 BTU
How to use
A 15×15 room is 225 square feet. At the common rule of 20 BTU per square foot, the base cooling load is about 4,500 BTU before people, sun and climate are added. A 15×15 room pushes past a tiny unit. Plan on a 6,000–8,000 BTU window or a small through-the-wall AC, more if two people use it often. Use the calculator to fold in your real ceiling height, insulation and climate zone.
FAQ
What size AC for a 15×15 room?
Start from about 4,500 BTU and adjust upward for sunny windows, poor insulation or a hot climate, and downward for a shaded, tight room. Most 15×15 rooms land near a 5,000–12,000 BTU unit depending on those factors.