What is DPI and what is PPI?

What should the DPI be? Is PPI pixels per inch or pages per inch?

Bookmobile uses DPI, dots per inch. We recommend any images are at least 300 DPI, dots per inch.

See our file guidelines here.


Bookmobile does not use pixels per inch. When we use the term PPI, we're referring to pages per inch, which determines the width of a book's spine.

See a list of our paper options and their PPIs here.

Calculate the spine width of a paperback here.