BTU Calculator for a 300 sq ft Room
A 300 sq ft room is 300 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=300, Ceiling height=8, People usually in room=1, Room type=living, Sun exposure=avg, Insulation quality=avg, Climate zone (1–5)=3 → 6,000 BTU, 0.50 ton, 6,000 BTU window unit, 10,500 BTU
How to use
A 300 sq ft room is 300 square feet. At the common rule of 20 BTU per square foot, the base cooling load is about 6,000 BTU before people, sun and climate are added. Three hundred square feet covers a bigger bedroom or a small apartment living room. Around 8,000 BTU is the sweet spot for average conditions. Use the calculator to fold in your real ceiling height, insulation and climate zone.
FAQ
What size AC for a 300 sq ft room?
Start from about 6,000 BTU and adjust upward for sunny windows, poor insulation or a hot climate, and downward for a shaded, tight room. Most 300 sq ft rooms land near a 5,000–12,000 BTU unit depending on those factors.