An image forming system includes an image forming apparatus and an upper device connected to the image forming apparatus. The image forming apparatus includes a first receiving unit for receiving a print mode including a cost priority mode; a first transmission unit for transmitting the print mode to the upper device; a second receiving unit for receiving a print instruction; a print control unit for printing the print data; a duplex print control unit for controlling a printing operation; and a fixing temperature control unit for controlling a fixing temperature. The upper device includes a first storage unit for storing a save setting; a third receiving unit for receiving image data; a second storage unit for storing the print mode; an arrangement print control unit for generating the print data; and a second transmission unit for transmitting the print instruction.