Heat pump size calculator
Enter your home’s heated and cooled area and your climate. You’ll get the capacity in BTU and the nearest heat pump size in tons.
Heat pump size
4 tons
- Capacity needed
- 45,000 BTU per hour
- Exact tons
- 3.75 tons
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Quick answers and tables: What size heat pump do I need?
How it works
Heat pumps are sized in tons, and one ton is 12,000 BTU per hour. A quick estimate multiplies floor area by about 25 BTU per square foot in mild climates, 30 in moderate ones and 35 in cold ones, where the heat pump has to keep up with winter heating rather than just summer cooling. The calculator adjusts for insulation and rounds up to the next half ton, the steps heat pumps are sold in.
Example
With heated and cooled area 1,500 sq ft, climate: moderate (zone 4: mid-Atlantic, Pacific NW), insulation: average, the answer is 4 tons.
Tips before you buy
- In cold climates, look for a cold-climate heat pump rated to keep its capacity at 5°F or below, or plan on backup heat.
- Get a Manual J load calculation before buying. Heat pump sizing matters more than with a furnace, because an oversized unit dehumidifies poorly in summer.
- Ductless mini-splits are sized per room or zone instead. Use the AC BTU or heater size calculator for single rooms.
Common questions
What size heat pump do I need for a 1,500 square foot house?
About 4 tons in a moderate climate with average insulation (45,000 BTU). In a mild climate, about 3.5 tons. In a cold climate, about 4.5 tons.
How many square feet does a 3 ton heat pump cover?
Roughly 1,200 square feet in a moderate climate and up to about 1,450 in a mild one, with average insulation.
How many BTU is a ton?
12,000 BTU per hour. A 3-ton heat pump is 36,000 BTU.