Air conditioner, method for calculating the length of the refrigerant pipe and calculating proper amount of refrigerant thereof

An air conditioner and a method for calculating the length of a refrigerant pipe and a proper refrigerant amount in the air conditioner are provided to fill a proper amount of refrigerant in the air conditioner by precisely calculating the length of the refrigerant pipe based on a communication time between an outdoor unit and an indoor unit. A method for calculating the length of a refrigerant pipe and a proper refrigerant amount in an air conditioner comprises the steps of measuring a communication time between an outdoor unit and an indoor unit(S10) and calculating the length of the refrigerant pipe based on the communication time between the outdoor unit and the indoor unit(S20). If the indoor unit includes a plurality of sub-indoor units, the length of the refrigerant pipe is calculated based on the communication time between the outdoor unit and the indoor unit and a communication time between the sub-indoor units.