Any size image will work with backstitch Reader however, we determined a ratio that fits well with many devices.
The general size that works well for both web and mobile is:
8.333 x 3.264 in or
1250 x 490
at a 150 resolution.
When an image is created at this size, it provides the best optimization for the app and image. Typically, the smaller the better when it comes to web and mobile apps. However, we know how important it is to have a quality image, which is why we came up with this formula.