How many pages will my book be, and how wide is the spine?
Put in your word count, a trim size and a paper, and get an estimate of the printed pages and how wide a spine your cover needs. If you already know the page count, start from that instead.
Paper thickness as of November 2026, from KDP's published figures. Check your printer's own calculator before you order a cover.
Pages and spine for your book
The page count is rounded up to an even number, since every leaf has two sides. Words a page are an estimate: dialogue, short paragraphs, chapter openings that start halfway down a page and scene breaks all use space, so a dialogue-heavy novel makes more pages than the sum says. For an exact count, lay out the book and count the pages in the PDF.
Words a page by trim
Estimates for a page of ordinary prose, with margins of about three quarters of an inch and room for a page number. Your designer's choices of typeface, size, leading and margins move these figures more than the trim does.
| Trim | Roomy | Standard | Compact |
|---|---|---|---|
| 4.25 × 6.87 in (mass market) | 115 | 145 | 175 |
| 5.06 × 7.81 in | 170 | 215 | 260 |
| 5 × 8 in | 175 | 220 | 265 |
| 5.25 × 8 in | 185 | 235 | 285 |
| 5.5 × 8.5 in | 215 | 270 | 325 |
| 6 × 9 in | 255 | 325 | 390 |
| 6.14 × 9.21 in | 270 | 345 | 415 |
| 7 × 10 in | 355 | 450 | 540 |
Paper and spine
The spine is the page count times the thickness of the paper. Cream paper is a little thicker than white, so the same book has a wider spine and a lower page limit. The limits below are for the common trims such as 5 × 8 in; larger trims and hardcovers have their own.
| Paper | Thickness a page | Pages KDP prints |
|---|---|---|
| White, black ink | 0.002252 in (0.0572 mm) | 24 to 828 |
| Cream, black ink | 0.0025 in (0.0635 mm) | 24 to 776 |
| Standard colour | 0.002252 in (0.0572 mm) | 72 to 600 |
| Premium colour | 0.002347 in (0.0596 mm) | 24 to 828 |
KDP prints words on the spine only from 79 or 80 pages (its help page says both), and asks for at least 0.0625 in of space between the spine text and each edge of the spine. IngramSpark and other printers publish their own figures: check theirs if you print elsewhere.
The full cover
A paperback cover is one image: the back, the spine and the front side by side, with 0.125 in of bleed on every outside edge. Its width is twice the trim width plus the spine plus the bleed on both sides; its height is the trim height plus the bleed at top and bottom. The spine is the last part a cover designer can finish, because it waits on the final page count; a change of paper or a late extra chapter moves it.
Sources
- KDP Help, Create a Paperback Cover. Spine width as page count times a thickness per paper, and the spine text rule.
- KDP Help, Print Options. The fewest and most pages a paperback can have, by ink and paper.
Paper thickness as of November 2026, from KDP's published figures, last read on November 4, 2026. Printers change their paper from time to time: check your printer's calculator, and download its cover template, before you order a cover. The words a page are our own estimates, not a printer's figures.
In Author Sweets
The PDF export sets a print interior at 5 × 8, 5.25 × 8, 5.5 × 8.5 or 6 × 9 in, four of the trims on this page, with the inside margin widened for the page count as print services ask. Choose white or cream paper and each PDF reports its real page count and spine width, worked out from the same figures as this page.
The word goal calculator says how long the draft will take to write, and book length by genre says how long readers of your genre expect it to be. The editing cost calculator prices the edit and the cover.