Cooling capacity answers the question "how much does this unit cool?". It is given in kilowatts (kW); 1 kW means removing 1 kilojoule of heat per second. Out of old habit kcal/h is still used, and American sources use BTU/h and tons of refrigeration: 1 kW ≈ 860 kcal/h ≈ 3,412 BTU/h, 1 ton of refrigeration ≈ 3.52 kW.
Capacity is not a fixed number; it changes with the operating condition. The same evaporator that gives 10 kW at a 0 °C room temperature may give 5 kW in a −25 °C room, and the same condensing unit cannot deliver at 42 °C the capacity it delivers in 32 °C outside air. That is why a catalog always states capacity together with a condition: room temperature, evaporating temperature, ambient temperature and the refrigerant used.
The capacity a cold room needs is calculated from its heat load: heat passing through the panels, cooling of incoming product, warm air entering when the door opens, people, lighting, fans and defrost heat are added up, divided by the number of hours the compressor will run per day, and a safety margin is added. Sonkar’s cooling load calculator does this calculation step by step.
When choosing equipment, matching the capacity one to one is not enough; the evaporator and the condensing unit must work in balance at the same evaporating temperature. The capacity search in the catalog lists compatible models for the kW and operating condition you enter.