BTU Calculator for a 12×12 Room
A 12×12 room is 144 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=144, Ceiling height=8, People usually in room=1, Room type=living, Sun exposure=avg, Insulation quality=avg, Climate zone (1–5)=3 → 3,000 BTU, 0.25 ton, 5,000 BTU window unit, 5,000 BTU
How to use
A 12×12 room is 144 square feet. At the common rule of 20 BTU per square foot, the base cooling load is about 2,880 BTU before people, sun and climate are added. A 12×12 bedroom or small living room is the classic "one window AC" size. Expect a 5,000–6,000 BTU unit unless it bakes in afternoon sun. Use the calculator to fold in your real ceiling height, insulation and climate zone.
FAQ
What size AC for a 12×12 room?
Start from about 2,880 BTU and adjust upward for sunny windows, poor insulation or a hot climate, and downward for a shaded, tight room. Most 12×12 rooms land near a 5,000–12,000 BTU unit depending on those factors.