Spine width
—
- Full cover with bleed
- —
- At 300 dpi
- —
- Cover without bleed
- —
- Bleed, each side
- 0.125 in3.18 mm
Your cover, to scale
How it is calculated
Page count × paper thickness.
A paperback spine is as thick as its pages. Each printer publishes how thick one page of each paper is; multiply it by your page count and you have the spine.
spine = pages × thickness of one page
cover width = bleed + back + spine + front + bleed
cover height = bleed + trim height + bleed
| Printer | Paper | One page |
|---|---|---|
| Amazon KDP | White | 0.002252 in · 0.0572 mm |
| Amazon KDP | Cream | 0.0025 in · 0.0635 mm |
| Amazon KDP | Standard color | 0.002252 in · 0.0572 mm |
| Amazon KDP | Premium color | 0.002347 in · 0.0596 mm |
| IngramSpark | White 50# | 1/512 in (512 pages per inch) |
| IngramSpark | Crème 50# | 1/444 in (444 pages per inch) |
| IngramSpark | Color 50# white | 1/512 in (512 pages per inch) |
| IngramSpark | Premium color 70# white | 1/377 in (377 pages per inch) |
| Other printer | Any | Sheet thickness ÷ 2 |
Bleed is 0.125 in (3.2 mm) on all four sides at both KDP and IngramSpark: the background runs past the trim line so no white edge shows after cutting.
IngramSpark rounds up an odd page count to the next even number, because its cover templates use an even (“mod 2”) spine. A 301-page book gets the spine of 302 pages.
Spine text. KDP asks for at least 80 pages before you put text on the spine; IngramSpark allows none below 48 pages. Keep the text 0.0625 in (1.6 mm) from each fold — at IngramSpark, 0.03125 in on spines thinner than 0.35 in. Below 0.2 in (about 5 mm) we suggest leaving the spine plain: the letters would be too small to read on a shelf.
Common mistakes
- Using the manuscript’s page count. The spine follows the final print PDF — title page, contents, blank versos and all. A Word document and a typeset book rarely have the same number of pages.
- Forgetting the paper. At KDP, cream is about 11% thicker than white: a 300-page book gains 0.074 in (1.9 mm) of spine.
- Reusing an old cover after edits. Add or cut a chapter and the spine changes. Recalculate after every change to the interior.
- Text right up to the folds. Spines can shift slightly in printing (KDP allows 0.0625 in either side of the folds), so titles that touch a fold can wrap onto the front or back.
- Building the cover for the wrong printer. The same 300 white pages make a 0.6756 in spine at KDP and 0.5859 in at IngramSpark. One cover file does not fit both.
Sources, checked 20 October 2026: Amazon KDP — Create a Paperback Cover · IngramSpark — Paper Specifications (rev. 8/18/23) · IngramSpark — File Creation Guide. Printers update their specifications from time to time; check your printer’s cover template before you send files.
Questions
Spine width, answered.
How do I calculate the spine width of my book?
Multiply the page count by the thickness of one page. On Amazon KDP white paper that is 0.002252 in per page, so a 300-page book has a 0.6756 in (17.16 mm) spine. Cream paper is 0.0025 in per page.
How many pages do I need for text on the spine?
Amazon KDP asks for at least 80 pages before you put text on the spine. IngramSpark allows no spine text on paperbacks under 48 pages. Keep the text 0.0625 in (1.6 mm) away from each fold.
What size is the full cover of a 6 × 9 paperback?
Back cover + spine + front cover, plus 0.125 in of bleed on every side. For a 300-page 6 × 9 book on KDP white paper: 0.125 + 6 + 0.6756 + 6 + 0.125 = 12.9256 in wide and 9.25 in tall.
Is the spine the same at KDP and IngramSpark?
No. IngramSpark’s white paper is thinner: 512 pages per inch, against KDP’s 0.002252 in per page. 300 white pages make a 0.5859 in spine at IngramSpark and 0.6756 in at KDP. Build the cover for the printer that will print it.
Does IngramSpark round the page count?
Yes. IngramSpark builds cover templates with an even page count, so an odd number of pages is rounded up: a 301-page book gets the spine of 302 pages.
Tellurin calculates this for you and builds the full cover — spine, bleed and barcode area included — from the book you typeset in it. About Tellurin