A mask and a controlling method thereof are disclosed. The mask includes a fan that provides an air volume to an inside of the mask, a valve that discharges air from the mask, a pressure sensor, and a processor. The processor may control the pressure sensor to detect a maximum pressure value and a minimum pressure value inside the mask worn by a user. The processor may identify a time for a single breath based on a maximum pressure value and a minimum pressure value detected at the pressure sensor. The processor may identify a number of breaths based on the identified time for the single breath and a predetermined time. The processor may control the fan to provide an air volume set at a level corresponding to the identified number of breaths among a plurality of levels divided based on a predetermined number of breaths.