Size your pool heat pump by surface area, not volume.

Yes, ignore pool volume for sizing — surface area is what matters. Heat pumps are sized to replace heat lost, not to warm a still body of water. And most heat loss happens at the surface through evaporation.

Here’s the rough math: take your pool’s surface area in square feet. Multiply by 10 to 14 BTUs depending on your climate and desired temperature rise. 10 for a mild climate with a 5°F rise, 14 for a cooler climate or a 10°F+ rise. That gives you the