There's no definitive answer to this question, as it depends on personal preference and the specific dimensions of your couch and the room it's in. However, as a general guide, you'll want to hang your pictures approximately 6-8 inches above the back of your couch. This will ensure that they're at a comfortable viewing height, without being too high or too low. Keep in mind that you may need to adjust this depending on the height of your couch cushions; if they're very thick, you may want to hang your pictures a bit higher so that they're still visible.