HVAC BTU Calculator
Determine the exact cooling and heating capacity your room needs.
Recommended Capacity
Understanding BTU and HVAC Sizing
Choosing the correct HVAC unit size is critical for home comfort, energy efficiency, and the longevity of your equipment. BTU stands for British Thermal Unit, which is a measure of heat energy. In the context of air conditioning, it represents how much heat the unit can remove from a room per hour.
Why Correct Sizing Matters
Many homeowners assume that "bigger is better" when it comes to air conditioners. However, an oversized unit will cycle on and off too frequently (short-cycling), which leads to uneven temperatures, higher electricity bills, and poor humidity control. Conversely, an undersized unit will run constantly without ever reaching the desired temperature, causing excessive wear and tear.
Factors in the Calculation
- Square Footage: The primary driver. Generally, you need about 20 BTUs per square foot of living space.
- Insulation: Homes with poor insulation or old single-pane windows lose cool air rapidly, requiring a higher BTU capacity.
- Sunlight: If a room is heavily shaded, you can reduce capacity by 10%. If it's very sunny, you should increase it by 10%.
- Occupancy: Each additional person beyond two occupants adds approximately 600 BTUs to the cooling load.
- Kitchens: Because of stoves and ovens, kitchens require an additional 4,000 BTUs of cooling capacity.
BTU to Tons Conversion
Residential AC units are often rated in "Tons." One ton of air conditioning is equivalent to 12,000 BTUs per hour. If our calculator suggests 24,000 BTUs, you would look for a 2-ton unit.
Expert Tip
Always consult with a licensed HVAC professional before purchasing a unit. This calculator provides a Manual J-style estimation, but a pro will look at your ductwork capacity and local climate zones for a perfect fit.