A 10,000 BTU air conditioner refers to the size of the air conditioning unit and the amount of area it can cool, which is approximately 450 square feet. BTU is the standard measurement of energy used in the HVAC industry to refer to the size rating of an AC unit.
A single BTU is measured by the amount of heat that can be removed from a room in an hour. This rating also helps determine the size of the room a specific unit can cool. For example, a 32,000 BTU unit can cool 1,600 square feet. The efficiency of the air conditioning unit depends on several other factors, such as appliance use, energy efficient windows and secured thresholds.