I created this graphic to help you visualize the amount of a photo that will be cropped off when printing at certain popular sizes. The only sizes that preserve the entire image without cropping are those with an aspect ratio (width to height ratio) of 2:3, as pictured on the far left.
The degree to which the cropping affects an image varies from image to image. For images with a lot of space around the subjects, cropping to a 16×20 may be just fine. However, in images where there are important elements close to the edge of the frame, consider choosing a size that does not change the aspect ratio of the original image. As always, please ask me if you have questions before placing your order! I can advise you on whether or not I think a particular image works when cropped to a particular size.