An image forming apparatus includes a cassette to store a recording medium, an image forming unit to form an image on an image bearing member based on an image forming condition, a transfer unit to transfer the image onto the recording medium conveyed from the cassette, and a reading unit to read a test image formed on the recording medium by the image forming unit. A controller controls the image forming unit to form the test image while the image forming unit is forming a plurality of images, controls the image forming condition based on a reading result of the test image by the reading unit, and obtains information related to basis weight of the recording medium in the cassette. In a case where the information does not satisfy a forming condition for forming the test image, the test image is not formed.