The cooling capacity of an air-conditioning unit is the ability to remove heat from a room and is usually measured in Btu per hour. The higher the Btu rating, the more heat will be removed. The capacity rating is usually given on the unit’s nameplate, together with other necessary information (such as voltage and wattage requirements). It is important that the room air-conditioning units be large enough for the room or rooms to be cooled. When dealing with large units, the term ton of refrigeration is most often used. A ton of refrigeration is equivalent to 12,000 Btu/hr. A room air conditioner rated at 10,000 Btu, for example, will supply 10/12, or 0.83, ton of refrigeration.