When choosing a standard photo size, aspect ratio is key to consider as it will dictate the width and height of photos. If the photograph and print are different sizes, it may be necessary to crop the image or add borders to fit it on the paper, according to Visuals Clipping. This may impact on the positioning of people, objects and other important details. By reviewing the aspect ratio before you print, you'll have more control of the final output, and you'll avoid losing parts of the image that you didn't expect.