An image forming apparatus includes an imaging unit, a fixing unit, a first thermometer, and a controller. The imaging unit forms a toner image on a recording medium conveyed along a media conveyance path. The fixing device is disposed downstream from the imaging unit along the media conveyance path to fix the toner image in place on the recording medium. The fixing device includes a fuser roller, a heat roller, an endless, fuser belt, and a pressure roller. The fuser roller has a cylindrical core of metal. The pressure roller presses against the fuser roller via the fuser belt to form a fixing nip therebetween. The first thermometer detects a first temperature at the cylindrical core of the fuser roller. The controller controls conveyance of the recording medium through the fixing nip according to the first temperature.