The aspect ratio is the longest side of your photo divided by the shortest side. If the aspect ratio of your image matches the aspect ratio of your print, then no cropping is required: you get the entire image on the entire print because the image shape projects directly onto the print shape.
For instance, many cameras capture an aspect ratio of 4:3, which is 4/3 or 1.33. That’s the same ratio as two dotphoto poster sizes: 40×30 and 24×18. dotphoto also offers a 4xD – the “digital print” (4xD) – that is 5.33″x4″, or an aspect ratio of 1.33.
How to find the Aspect Ratio of your Camera or Phone
Upload to dotphoto. In an album, tap on Organize, then Edit Titles. You’ll see the width and height of your photos in pixels. Divide the longest side by the shortest side to find the aspect ratio. In the illustration here, the aspect ratio is 1.33, which perfectly matches the 4″xD print. If the aspect ratio were 1.5, it would match 4″x6″ prints (6/4=1.5).