What does the ton mean in the size of an air conditioner?

The term "ton" in the context of air conditioning refers to the cooling capacity of the unit, specifically the amount of heat it can remove from a space in one hour. One ton is equivalent to the ability to cool 12,000 British thermal units (BTUs) per hour. This measurement originates from the amount of heat required to melt one ton of ice in a 24-hour period, which is why it's used to describe cooling power. A larger tonnage indicates a greater cooling capacity suitable for larger spaces.