🌡️ HVAC BTU & Room Size Calculator
Calculate required heating and cooling capacity to properly size AC units and heaters
Room Dimensions
Room Characteristics
How to Use
- Measure your room dimensions (length, width, ceiling height)
- Select your climate zone and insulation quality
- Count windows and assess sun exposure
- Enter number of regular occupants and room type
- Click "Calculate BTU Requirements" to see sizing recommendations
HVAC Sizing Guide
BTU vs. Tons
1 ton = 12,000 BTU/hr. Room ACs are rated in BTU (5,000-24,000). Central AC rated in tons (1.5-5 ton). Standard rule: 20 BTU per sq ft, adjusted for factors.
Adjustment Factors
Base 20 BTU/sq ft. Add: +10% per person over 2, +10% for kitchens, +10% for high sun exposure, +15% for poor insulation. Subtract: -10% for good insulation, -10% for shaded rooms.
SEER Ratings
SEER measures AC efficiency. Minimum 14 SEER (DOE standard). 16+ SEER is high-efficiency. Each +1 SEER = ~7% energy savings. Higher upfront cost, lower operating cost.
Heating Capacity
Heating needs 25-30% more BTU than cooling in cold climates. Heat pumps provide both heating and cooling. Supplemental heat may be needed below 30°F.