hvac size calculator
Professional cooling capacity estimator • Worldwide climate standards • US reference data
📐 1. Building & load factors
🇺🇸 USA typical: 1 ton of cooling per 500–600 sqft in moderate climate. Adjust for other factors.
Cooling priority: hot climates demand larger capacity (frequent 95°F+ days). Cold climates reduce cooling need.
🇺🇸 DOE: Better insulation reduces required BTU by up to 20% → lower bills.
Extra solar heat gain increases required BTUs. Reflective films or curtains help.
Each person adds sensible + latent heat. Typical recommendation: +600 BTU/h.
Based on your selected year, we recommend minimum SEER2 efficiency (US Energy regulations).
💡 Pro tip from HVAC specialists: Oversizing causes short cycling & humidity issues. Undersizing leads to poor comfort. Our calculator uses load factors (climate + insulation + sun) to find the balanced capacity. Always verify with Manual J for precision.
📘 How to use this tool
1. Enter your home/building area (sqft or m²).
2. Choose climate, insulation, windows & sun exposure – each factor adjusts the final BTU.
3. Add number of people living/working there.
4. Input the model year for efficiency reference (any year).
5. The results + graph update automatically. Use the recommended tonnage to select HVAC equipment.
1. Enter your home/building area (sqft or m²).
2. Choose climate, insulation, windows & sun exposure – each factor adjusts the final BTU.
3. Add number of people living/working there.
4. Input the model year for efficiency reference (any year).
5. The results + graph update automatically. Use the recommended tonnage to select HVAC equipment.
⚡ Calculated HVAC size
— BTU/h
— Tons
✅ Final Sizing summary
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📋 Factor influence (USA standards)
- Climate: Hot (e.g., Florida, Texas) → +30% capacity needed
- Insulation: Poorly insulated homes (pre-1980) → +20% load
- Windows/Sun: Full sun + many windows → up to +20% extra BTU
- Occupants: Each person = +600 BTU (kitchen/appliances not included)
- Rule of thumb baseline: 25 BTU per sqft for moderate zone