Measure the horizontal width of your print (the vertical length does not matter). We recommend the Hanger Frame to be 1 inch longer than the width of your print. It does not have to be exact, as seen in these pictures. It just depends on the amount of wood overhang you want. We offer 14 standard sizes and we also offer custom sizes for an additional fee. But many customers choose a standard size close to their print width, which will usually still work well.