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This heat pump size calculator estimates the size of heat pump your home needs in tons. It sizes the system for cooling, then compares its rated capacity with your home’s estimated heating load to show whether you may need a cold-climate model or backup heat.
How to Use the Heat Pump Size Calculator
- Enter the conditioned floor area.
- Choose the climate that best matches your region.
How the Size Is Estimated
Cooling load ≈ Area × 20 BTU per sq ft; Tons = Cooling load ÷ 12,000 (rounded up to ½ ton)
Heating load ≈ Area × 30–60 BTU per sq ft (by climate)
Heat pumps are usually sized to the cooling load so they dehumidify well in summer. In cold weather their heating output falls, so the calculator shows the gap between the heating load and the unit’s nominal capacity.
Example
An 1,800 sq ft home has a cooling load of about 36,000 BTU, so a 3-ton heat pump. In a cold climate its heating load could be 90,000–108,000 BTU, far above the unit’s 36,000 BTU rating, so it would need a cold-climate heat pump sized for heating, a dual-fuel furnace or electric backup heat.
Heat Pump Size Chart
| Home size | Approx. heat pump size |
|---|---|
| 900 sq ft | 1.5 ton |
| 1,200 sq ft | 2.0 ton |
| 1,500 sq ft | 2.5 ton |
| 1,800 sq ft | 3.0 ton |
| 2,100 sq ft | 3.5 ton |
| 2,400 sq ft | 4.0 ton |
| 3,000 sq ft | 5 ton |
Tips for Choosing a Heat Pump
- In cold climates, look for cold-climate models that keep most of their capacity at 5°F (−15°C).
- Variable-speed (inverter) heat pumps handle part loads better and are more comfortable.
- Ask for a Manual J load calculation; this calculator gives only a rough starting point.
- Check federal tax credits and utility rebates for qualifying heat pumps.
Compare with a furnace using the furnace size calculator, or estimate installation cost with the AC replacement cost calculator.
Sources
Frequently Asked Questions
What size heat pump do I need for a 2,000 sq ft house?
Roughly 3.5 tons by the 20 BTU per sq ft cooling rule, but climate, insulation and windows can change this; a Manual J calculation is best.
How many square feet does a 3-ton heat pump cover?
Roughly 1,500–1,800 sq ft in a typical climate, using common rules of thumb.
Do heat pumps work in cold climates?
Yes. Cold-climate heat pumps can heat homes well below freezing, though output drops as temperatures fall.
What happens if a heat pump is too big?
It short-cycles, removes less humidity in summer and wears out faster.
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