It is recommended to submit covers for perfect bound document as three files — the front cover, the back cover, and the spine. The size of your front and back cover should equal the finished size of your document plus 1/8 inch bleed on all four sides of the page.
To calculate the spine size, use this formula:
For 60# uncoated text, 70# matte and gloss text, and 80# matte and gloss text stock:
Number of pages divided by 440 = spine in inches
For 70# uncoated text and 100# matte and gloss text stock:
Number of pages divided by 370 = spine in inches
Include the cover when counting pages. When adding text to the spine, do not make the size of the text exactly equal to the width of the spine. Leave blank room on both sides of the text.
For example, if your book is 100 pages and you are using 80# matte stock, your perfect bound book spine would be 100 pages divided by 440, or .23 inches. If you were using 70# uncoated stock, the spine would be 100 pages divided by 370, or .27 inches.