To choose the right size art frame for your painting, it is important that you take accurate measurements. First, measure the width and height of your painting and jot it down. If your painting is on a pre-stretched canvas, it should be fairly easy to find a ready-made frame that accommodates your canvas size. If, however, your canvases are custom sizes, you may need to order custom frames. Either way, your painting will look museum-worthy once housed in the perfect painting frame.