An image forming apparatus includes: a cartridge attachment portion; an image forming unit; a reading unit; and a control unit. A toner cartridge configured to accommodate toner is removably attached to the cartridge attachment portion. The toner cartridge includes a cartridge mechanism unit mechanically driven and a storage medium for storing torque information including information indicating torque used for a mechanical drive of the cartridge mechanism unit. The image forming unit is configured to print an image on a surface of a printing medium using toner accommodated in the toner cartridge. The reading unit is configured to read the torque information from the toner cartridge attached to the cartridge attachment portion. The control unit is configured to determine a number of printing media to be printed by the image forming unit per unit time, according to the torque information read by the reading unit.