An image forming apparatus controls a first image forming unit and a second image forming unit to form a plurality of pattern images. The plurality of pattern images includes a first pattern image formed by the first image forming unit, a second pattern image formed by the second image forming unit, a plurality of third pattern images that are formed by the first image forming unit and have different tones from one another, and a plurality of fourth pattern images that are formed by the second image forming unit and have different tones from one another. The image forming apparatus obtains data that has been output from a sensor and is related to the plurality of pattern images, and generates the conversion condition based on the data.