HVAC Sizing & BTU Calculator
Determine the cooling and heating capacity required for your space.
How HVAC Sizing Works
Choosing the right size for your heating, ventilation, and air conditioning (HVAC) system is critical for both comfort and energy efficiency. An undersized unit will run constantly, failing to reach the desired temperature, while an oversized unit will "short cycle," turning on and off too quickly. Short cycling prevents the system from properly dehumidifying the air, leading to a clammy environment and increased wear and tear on the compressor.
What is a BTU?
BTU stands for British Thermal Unit. It is a measure of heat energy. In HVAC terms, it represents how much heat an air conditioner can remove from a room or how much heat a furnace can add to a room in one hour. 12,000 BTUs is equal to 1 "Ton" of cooling capacity.
HVAC Tonnage Chart
| Square Footage | Required BTUs | Tons |
|---|---|---|
| 600 – 1,000 | 18,000 | 1.5 Tons |
| 1,000 – 1,500 | 24,000 | 2.0 Tons |
| 1,500 – 2,000 | 30,000 | 2.5 Tons |
| 2,000 – 2,500 | 36,000 | 3.0 Tons |
Realistic Example Calculation
Suppose you have a 2,000 square foot home with standard 8-foot ceilings and average insulation. The base calculation starts at roughly 20 BTUs per square foot.
- Base Calculation: 2,000 sq ft × 20 = 40,000 BTUs.
- Ceiling Adjustment: If you have 10-foot ceilings, you have 25% more air volume, increasing the requirement to 50,000 BTUs.
- Sunlight Factor: If the house is in direct sunlight with many windows, you might add 10%, bringing the total to 55,000 BTUs.
In this scenario, a professional would likely recommend a 4.5 or 5-ton unit to ensure the home stays cool during peak summer months.