An image forming apparatus includes a printing device to print images on sheets using a printing operation and to initiate a discharge of printed sheets from a sheet discharge port onto the discharge tray disposed for the image forming apparatus; a counter operatively connected to the printing device to count the number of printed sheets based on content of a print job; a controller to determine whether the number of printed sheets counted by the counter reaches a maximum sheet stacking capacity of the discharge tray, the maximum sheet stacking capacity being determined by a distance between the sheet discharge port and the discharge tray; and a reporting device to report that the discharge tray is full when the controller determines that the number of printed sheets counted by the counter reaches the maximum sheet stacking capacity.