⚡ Heat Pump Sizing Calculator
Enter your home's design heat loss to convert it into the heat-pump capacity you need — in kilowatts and tons — and size the unit to the load instead of oversizing.
🧮 Size Your Heat Pump
What is a Heat Pump Sizing Calculator?
It translates a heat loss figure into buyable capacity. Give it your home's design heat loss in BTU/hr and it returns the heat-pump output you need in both kilowatts and refrigeration tons — the two ways manufacturers rate their units — so you can shortlist models with confidence.
Use it after a heat loss calculation to check a quote, compare an air-source and ground-source option, or understand why an installer specced the size they did. Size to the calculated load: a right-sized pump runs longer, quieter, and far more efficiently than an oversized one.
❓ Frequently Asked Questions
How does the heat pump sizing calculator work?
Enter your building's design heat loss in BTU per hour. The tool divides by 3,412 to give the capacity in kilowatts and by 12,000 to give it in refrigeration tons — two common ways heat-pump output is specified — so you can match a unit to your calculated load.
Where do I get the heat loss figure?
From a heat loss calculation. Add up the fabric loss through every wall, roof, floor, window, and door at your design temperature, plus ventilation losses, to get a whole-house BTU/hr figure. Our heat loss calculator does the per-element maths you can total up.
Why shouldn't I just buy a bigger heat pump to be safe?
Because oversizing backfires. A heat pump that's too large short-cycles — switching on and off rapidly — which lowers efficiency, wears the compressor, and gives poorer comfort and humidity control. Sizing to the calculated load lets the unit run long, steady, efficient cycles.
What do kW and tons mean here?
Both express heating capacity. A kilowatt is 3,412 BTU/hr of output; a refrigeration ton is 12,000 BTU/hr. Manufacturers in different markets quote one or the other, so the calculator gives both to make comparing models easier. Always confirm the rated capacity at your design outdoor temperature.