A good rule of thumb is to choose wall art that takes up the width of the wall, minus 6-12 inches on each side, so it looks like it’s centered, like the image above. For example, you have a 36 inch wall. Leave about 6 inches on each side of the piece of art, which means you should choose something around 24 inches wide.
What if you are hanging wall art over a sofa, bed or table? Choose a piece of art (or a series) that is the same length as the furniture piece or smaller. Avoid wall decor that is wider than the furniture piece; it looks totally weird.