BTU per hour measures how much heat a chiller can remove in an hour. One BTU is the energy needed to raise a pound of water by 1°F, so a 5,000 BTU/h chiller removes roughly the heat of 5,000 pounds of water dropping one degree each hour. It is the only figure that lets you compare cooling capacity across brands.
Why it matters when you are comparing products
Horsepower ratings are inconsistent between manufacturers, but BTU/h is a physical measurement. When a maker publishes both, compare on BTU/h.
Where this comes up
- Chillers — Compared on published BTU/h where the maker states it.
- What size cold-plunge chiller do you need? — Turning BTU/h into a tub-size recommendation.
Reviewed 2026-08-15