An air conditioning capacity calculating system (10) including: a first acquisition unit (71) configured to acquire outdoor unit capacity information related to a rated capacity of an outdoor unit (40) of an air conditioning apparatus (20); a measurement unit (72) configured to measure power consumption of the outdoor unit; a second acquisition unit (73) configured to cooperate with a temperature sensor and for acquiring an outside air temperature; and a capacity calculating unit (74) configured to obtain a calculation value of the capacity of the air conditioning apparatus based on the outdoor unit capacity information, the power consumption, and the outside air temperature. The capacity calculating unit is configured to select, based on the outdoor unit capacity information, one from among a plurality of capacity calculation models each of which includes a characteristic formula that expresses a relationship between the power consumption and the capacity.