An image forming apparatus includes a developing unit, a transfer section, and a calculator. The developing unit includes an image carrier carrying a developer image. The transfer section includes a transfer belt, a cleaning member, and a container, and transfers the developer image onto a print medium. The transfer belt is disposed in contact with the image carrier. The cleaning member removes a developer attached to the transfer belt. The container contains the developer removed by the cleaning member. The calculator calculates a collection amount on the basis of medium information of the print medium. The collection amount is an amount of the developer collected in the container.