An image forming apparatus comprising: a heating determination unit (1710, 1707) configured to determine a heating amount by using the processor, the heating determination unit (1707, 1710) configured to identify a heating amount to fuse a toner image of the target image from the overlapping portion that can effectively fuse the first toner image, and the second toner image; an image forming unit configured to form the toner image of the target image on a transfer member by forming the first toner image, and the second toner image on the transfer member; a transfer unit configured to transfer the toner image of the target image formed on the transfer member to a recording medium; a fusing unit configured to fuse the toner image of the target image, transferred by the transfer unit, on the recording medium using the heating amount determined by the heating determination unit, characterized by a computing unit including a processor, configured to compute a total amount of toner to be deposited per unit area of a target image to be formed based on image data, wherein a first unit area is computed to form a first toner image using a highest total amount of toner, and wherein a second unit area is computed to form a second toner image using a lowest total amount of toner; a storage unit configured to include a heater output management database storing heater output information about heating amounts of toner per unit area of toner images on sheets; wherein the heating determination unit (1710, 177) determines when the highest total amount of toner computed by the computing unit exceeds a given level, 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 the first toner image and the second toner image, wherein the heater output management database is searched for the corresponding heating amounts. a heating determination unit (1710, 1707) configured to determine a heating amount by using the processor, the heating determination unit (1707, 1710) configured to identify a heating amount to fuse a toner image of the target image from the overlapping portion that can effectively fuse the first toner image, and the second toner image; an image forming unit configured to form the toner image of the target image on a transfer member by forming the first toner image, and the second toner image on the transfer member; a transfer unit configured to transfer the toner image of the target image formed on the transfer member to a recording medium; a fusing unit configured to fuse the toner image of the target image, transferred by the transfer unit, on the recording medium using the heating amount determined by the heating determination unit, characterized by a computing unit including a processor, configured to compute a total amount of toner to be deposited per unit area of a target image to be formed based on image data, wherein a first unit area is computed to form a first toner image using a highest total amount of toner, and wherein a second unit area is computed to form a second toner image using a lowest total amount of toner; a storage unit configured to include a heater output management database storing heater output information about heating amounts of toner per unit area of toner images on sheets; wherein the heating determination unit (1710, 177) determines when the highest total amount of toner computed by the computing unit exceeds a given level, 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 the first toner image and the second toner image, wherein the heater output management database is searched for the corresponding heating amounts.