Spine Size

The spine size is determined by dividing the total number of inside text pages including blank pages, by the ppi (pages per inch) of the paper used. The ppi is located on the "Standard Text Papers" link under "Products & Services".

For example white 50# offset is 512ppi. and if your book is 300 total inside pages, divide 300 by 512 = 0.586".
Make you book spine width 0.586".