An image forming apparatus includes a processor that derives, for each of a plurality of blocks of image data, a value indicating a toner amount to be used in forming a toner image by referring to a density of every pixel, of a plurality of pixels included in each block of image data, shifts a window, and outputs the window before shifting and the window after shifting, the window before shifting and the window after shifting overlapping with each other, and determines a fixing temperature for a fixing operation based on an analysis result of a first toner amount in the window that is output by referring to the toner amount of each block included in the window before shifting, and an analysis result of a second toner amount in the window that is output by referring to the toner amount of each block included in the window after shifting.