An image forming apparatus and method compute a total amount of toner to be deposited per unit area of a target image. When the highest total amount of toner computed exceeds a given level, a heating determination unit, using a processor, determines whether a first heating amount range enabling fusing of the computed highest total amount of toner and a second heating amount range enabling fusing of the computed lowest total amount of toner have an overlapping portion that can effectively fuse a first toner image, a second toner image, and identifies a heating amount to fuse a toner image of the target image from an overlapping portion that can effectively fuse the first toner image, and the second toner image.