Heat Pump Size Calculator
Estimate the required BTU and Tonnage for your home
How Much Heating and Cooling Capacity Do You Need?
Choosing the correct size for a heat pump is critical for both comfort and efficiency. An undersized unit will fail to keep your home warm during peak winter months, while an oversized unit will "short-cycle," turning on and off too frequently, which wastes energy and puts unnecessary wear on the compressor.
What is a BTU?
BTU stands for British Thermal Unit. It is a measurement of thermal energy. In the HVAC world, it represents how much heat a system can move in one hour. Most residential heat pumps range from 18,000 to 60,000 BTUs.
Understanding Tonnage
Air conditioners and heat pumps are often rated in "Tons." This doesn't refer to the weight of the machine, but rather its cooling capacity. One ton of refrigeration is equal to 12,000 BTUs per hour. Therefore:
- 1.5 Tons: 18,000 BTUs
- 2.0 Tons: 24,000 BTUs
- 3.0 Tons: 36,000 BTUs
- 5.0 Tons: 60,000 BTUs
Factors That Influence Heat Pump Sizing
While square footage is the primary driver, other factors play a significant role in the final calculation:
- Climate Zone: Homes in Maine require significantly more heating capacity than homes in Florida, even if the square footage is identical.
- Insulation: Well-insulated homes with double-pane windows retain heat better, allowing for a smaller, more efficient heat pump.
- Ceiling Height: High vaulted ceilings increase the volume of air that needs to be conditioned, requiring higher BTU outputs.
Why Professional Manual J Calculations Matter
This calculator provides a high-level estimate based on regional averages. However, for a precise installation, HVAC professionals perform a "Manual J Load Calculation." This detailed assessment looks at the orientation of your home, the number of occupants, the type of flooring, and even the local shading to ensure the unit is perfectly matched to your building envelope.