An air conditioner comprising: a display; a storage; a sensor configured to sense the indoor temperature; a processor; and a communication unit, the processor being configured to: store, in the storage, information including power consumption information and time information which are required to increase or decrease an indoor temperature by a unit temperature according to an outdoor temperature; receive, through the communication unit, outdoor temperature information corresponding to the outdoor temperature of an area in which the air conditioner is to be disposed predict, based on a desired temperature being input, at least one of a first power consumption or a first required time for the indoor temperature to reach the desired temperature based on the information stored in the storage, the received outdoor temperature information and the indoor temperature, provide at least one of the first power consumption or the first required time through the display, based on the indoor temperature being increased or decreased by a predetermined unit temperature, obtain a second power consumption and a second required time which are consumed by the air conditioner for the indoor temperature to increase or decrease by the unit temperature, compare at least one of the second power consumption or the second required time with at least one of the power consumption information or the time information, respectively, provide a feedback according to a comparison result, and based on the comparison result exceeding a predetermined error range, provide a guide on the indoor environment in which the air conditioner is positioned, wherein the guide comprises one of guiding to check whether excessive outside air enters the indoor environment or guiding to check whether excessive outside light enters the indoor environment. a display; a storage; a sensor configured to sense the indoor temperature; a processor; and a communication unit, the processor being configured to: store, in the storage, information including power consumption information and time information which are required to increase or decrease an indoor temperature by a unit temperature according to an outdoor temperature; receive, through the communication unit, outdoor temperature information corresponding to the outdoor temperature of an area in which the air conditioner is to be disposed predict, based on a desired temperature being input, at least one of a first power consumption or a first required time for the indoor temperature to reach the desired temperature based on the information stored in the storage, the received outdoor temperature information and the indoor temperature, provide at least one of the first power consumption or the first required time through the display, based on the indoor temperature being increased or decreased by a predetermined unit temperature, obtain a second power consumption and a second required time which are consumed by the air conditioner for the indoor temperature to increase or decrease by the unit temperature, compare at least one of the second power consumption or the second required time with at least one of the power consumption information or the time information, respectively, provide a feedback according to a comparison result, and based on the comparison result exceeding a predetermined error range, provide a guide on the indoor environment in which the air conditioner is positioned, store, in the storage, information including power consumption information and time information which are required to increase or decrease an indoor temperature by a unit temperature according to an outdoor temperature; receive, through the communication unit, outdoor temperature information corresponding to the outdoor temperature of an area in which the air conditioner is to be disposed predict, based on a desired temperature being input, at least one of a first power consumption or a first required time for the indoor temperature to reach the desired temperature based on the information stored in the storage, the received outdoor temperature information and the indoor temperature, provide at least one of the first power consumption or the first required time through the display, based on the indoor temperature being increased or decreased by a predetermined unit temperature, obtain a second power consumption and a second required time which are consumed by the air conditioner for the indoor temperature to increase or decrease by the unit temperature, compare at least one of the second power consumption or the second required time with at least one of the power consumption information or the time information, respectively, provide a feedback according to a comparison result, and based on the comparison result exceeding a predetermined error range, provide a guide on the indoor environment in which the air conditioner is positioned, wherein the guide comprises one of guiding to check whether excessive outside air enters the indoor environment or guiding to check whether excessive outside light enters the indoor environment.