Chiller Ton: What 'Tons Of Cooling' Means And How To Calculate It July 31, 2026 If you've specified commercial cooling equipment, you've encountered capacity measured in 'tons' — and if you didn't grow up in the industry, the unit seems arbitrary. It has historical roots, but understanding it matters because it's the primary unit of capacity for commercial and industrial cooling equipment in North America. Getting comfortable with it, and knowing how to convert to and from other units, is essential for anyone working with commercial cooling systems. Where 'Ton of Cooling' Comes From The ton as a unit of cooling capacity originated in the 19th century, when mechanical refrigeration was replacing harvested ice as a cooling method. The reference point: how much cooling effect does a ton (2,000 lbs) of ice provide as it melts over 24 hours? A ton of ice absorbs approximately 288,000 BTU as it melts at 32 degrees F (144 BTU per pound). Spread over 24 hours, that's 12,000 BTU/hr. That rate became the definition of one ton of refrigeration. The Conversions You Need From To (Multiply By) Tons of refrigeration BTU/hr: x 12,000 Tons of refrigeration kW (thermal): x 3.517 BTU/hr Tons: divide by 12,000 kW (electrical input) BTU/hr (cooling): x 3,412 kW (thermal cooling) Tons: divide by 3.517 Practical Examples A 100-ton chiller removes 100 x 12,000 = 1,200,000 BTU/hr of heat from the process or building it serves A building with a 500,000 BTU/hr peak cooling load requires a chiller with at least 500,000 / 12,000 = 41.7 tons of capacity — specify the next standard size above that A data center with 500 kW of IT load needs to remove approximately 500 x 3.412 = 1,706,000 BTU/hr, which is 1,706,000 / 12,000 = 142 tons How Chiller Efficiency is Measured: kW/ton Chiller efficiency is commonly expressed as kW per ton — electrical input required to produce one ton of cooling. Lower is better: kW/ton Rating Context 0.4-0.5 kW/ton High-efficiency magnetic bearing compressor chillers (TurboCor) at part load 0.5-0.6 kW/ton High-efficiency variable speed commercial chillers at full load 0.6-0.8 kW/ton Standard commercial efficiency 0.8-1.0 kW/ton Older or lower-efficiency equipment; also variable-speed at full load in hot ambient Above 1.0 kW/ton Inefficient; consider replacement or maintenance intervention > AHRI 550/590 is the standard testing protocol for commercial chiller efficiency ratings. When comparing chillers, ensure you're comparing rated performance at equivalent conditions — AHRI full-load and IPLV (Integrated Part Load Value) ratings allow apples-to-apples comparison. Frequently Asked Questions Is a 'ton' of cooling the same in all contexts? In North American commercial refrigeration and HVAC, yes — one ton = 12,000 BTU/hr. In some international contexts, the term 'ton' may refer to different values. The RT (refrigeration ton) is standard in North American commercial equipment. What's the difference between tons and tonnage? No functional difference — 'tonnage' is simply the total number of tons of capacity. '100 tons of cooling' and '100 tonnage' refer to the same thing. Context usually makes the meaning clear. > Get help sizing a chiller for your commercial or industrial load -> Contact us