BTU calculator by room size: 200 to 1,200 square feet

One page per room size with the transparent formula (20 BTU per square foot), the standard adjustments for sun, shade, kitchens and occupancy, tons and kW conversions, and the unit class to shop for. Oversizing is the number-one mistake — every page says where to stop.

• 200 sq ft
• 300 sq ft
• 400 sq ft
• 500 sq ft
• 600 sq ft
• 700 sq ft
• 800 sq ft
• 900 sq ft
• 1000 sq ft
• 1100 sq ft
• 1200 sq ft

Method: BTU sizing guide. India: tonnage rules. Metric (French): puissance par m².