An image forming apparatus includes a controller, a database, an image carrier, a transfer unit, a fixing device including a temperature detector and a first drive device, a speed changer, and an electric-current detector. The controller calculates a toner adhesion amount of a recording medium, identifies a type of the recording medium, detects a temperature of the fixing device, determines a moisture content of the recording medium, calculates a reaction force of the recording medium, calculates a toner adhesion force, compares the reaction force and the toner adhesion force, determines a fixing nip angle, drives the first drive device to set the fixing device to the fixing nip angle, determines a target feed speed of the recording medium, and drives the speed changer to change a feed speed of the recording medium to match the target speed.