Heat Pump Size Calculator
Estimate the heating capacity a heat pump needs for your home, in BTU/h and tons, from home size, insulation and the winter design temperature for your state.
Connecticut, design temperature 13°F
2 tons
23,750 BTU/h design heating load (11.9 BTU/h per sq ft)
A heat pump should deliver at least 23,750 BTU/h at 13°F. Many heat pumps lose capacity as it gets colder, so check the manufacturer's output at that temperature, not the nameplate size.
This load is below the 20–60 BTU/h per sq ft rule of thumb. That is common for well-insulated homes and milder climates; if your home is older or leaky, try the drafty setting.
This is an estimate, not a Manual J load calculation.
Estimate only. A contractor should perform a Manual J load calculation before you buy equipment.
Heat pump size by square footage and climate
Average insulation, 70°F indoors, rounded up to the next half ton. Estimates only.
| Home size | Mild (30°F) | Cool (15°F) | Cold (0°F) | Very cold (−10°F) |
|---|---|---|---|---|
| 1,000 sq ft | 1 tons | 1 tons | 1.5 tons | 1.5 tons |
| 1,500 sq ft | 1.5 tons | 1.5 tons | 2 tons | 2.5 tons |
| 2,000 sq ft | 1.5 tons | 2 tons | 2.5 tons | 3 tons |
| 2,500 sq ft | 2 tons | 2.5 tons | 3.5 tons | 3.5 tons |
| 3,000 sq ft | 2.5 tons | 3 tons | 4 tons | 4.5 tons |
Why cold-climate heat pumps need capacity at 5°F
A heat pump's output falls as the temperature drops, while your home's heat loss rises. A unit sized only by its nameplate can fall short on the coldest days. Compare a model's rated output at 5°F, or at your design temperature, with the load above.
Get a Manual J load calculation
Our estimate uses a single heat-loss factor for your whole home. A Manual J calculation looks at windows, walls, air leakage and ducts room by room. Ask your contractor to perform one before you buy equipment.
Frequently asked questions
What size heat pump do I need?
It depends on your heating load at your design temperature, not only square footage. The calculator estimates the load from home size, insulation and your state's winter design temperature.
How many tons is a 2,000 sq ft house?
With average insulation in Connecticut, our estimate is about 2 tons. Colder states need more, milder states less. This is an estimate, not a Manual J load calculation.
What is a Manual J load calculation?
Manual J is the industry method contractors use to calculate a home's heating and cooling load room by room. Ask your contractor for one before you buy equipment.
Why does design temperature matter?
Heat pumps deliver less heat as it gets colder. Sizing for the coldest typical day makes sure the system keeps up, so check a model's capacity at your design temperature.