An image forming apparatus, in which an image forming method is performed, includes an image forming device to form an image on a recording medium, a reading device to scan the recording medium having a mark and generate a scanned image, and circuitry to calculate a correction value to adjust a position of the image to be formed on the recording medium, based on the scanned image. The circuitry calculates the correction value to adjust a position of an image to be formed on a second face of the recording medium based on a first scanned image generated from a first face of the recording medium, within a period from when the first scanned image is generated from the first face to when the image starts to be formed on the second face.