Best Trim Size for Your KDP Paperback
Trim size is the finished width and height of your printed book after the pages are cut. It's one of the first decisions you make when publishing on Amazon KDP — and one of the hardest to change later, since your interior formatting, cover dimensions, and spine width all depend on it.
Amazon KDP offers 14 trim sizes for paperbacks. Choosing the wrong one means your book will look amateurish on the shelf, feel awkward in readers' hands, or cost more to print than it needs to. This guide covers every available size, which genres they suit, and how trim size affects your printing cost and profit margin.
The short answer
If you're publishing fiction (novels, short stories, literary fiction), go with 5.5" × 8.5" or 5" × 8". If you're publishing nonfiction (guides, self-help, business), go with 6" × 9". These three sizes account for the vast majority of self-published books on Amazon because readers expect them — pick up any paperback at a bookstore and it's almost certainly one of these sizes.
All 14 KDP paperback trim sizes
| Trim Size | Inches | mm | Cost Tier | Best For |
|---|---|---|---|---|
| 5" × 8" | 5 × 8 | 127 × 203 | Regular | Fiction, poetry |
| 5.06" × 7.81" | 5.06 × 7.81 | 129 × 198 | Regular | EU standard (B-format) |
| 5.25" × 8" | 5.25 × 8 | 133 × 203 | Regular | Fiction, memoirs |
| 5.5" × 8.5" | 5.5 × 8.5 | 140 × 216 | Regular | ★ Fiction, self-help |
| 6" × 9" | 6 × 9 | 152 × 229 | Regular | ★ Most popular overall |
| 6.14" × 9.21" | 6.14 × 9.21 | 156 × 234 | Large | EU standard (Royal) |
| 6.69" × 9.61" | 6.69 × 9.61 | 170 × 244 | Large | Textbooks, reference |
| 7" × 10" | 7 × 10 | 178 × 254 | Large | Workbooks, manuals |
| 7.44" × 9.69" | 7.44 × 9.69 | 189 × 246 | Large | EU standard (Crown Quarto) |
| 7.5" × 9.25" | 7.5 × 9.25 | 190 × 235 | Large | Cookbooks, photo books |
| 8" × 10" | 8 × 10 | 203 × 254 | Large | Activity books, portfolios |
| 8.25" × 6" | 8.25 × 6 | 210 × 152 | Large | Landscape (children's) |
| 8.25" × 8.25" | 8.25 × 8.25 | 210 × 210 | Large | Square (photo, coffee table) |
| 8.5" × 11" | 8.5 × 11 | 216 × 279 | Large | Coloring books, planners, workbooks |
Sizes are split into two pricing tiers: regular (≤ 6" × 9") and large (> 6" × 9"). Large trim sizes cost more per page to print, which directly reduces your royalty per sale. Check the exact cost difference for your page count with the royalty calculator.
Recommended trim size by genre
How trim size affects printing cost
KDP splits trim sizes into two cost tiers. Regular sizes (up to 6" × 9") have a lower per-page printing cost. Large sizes (above 6" × 9") cost more per page because they use more paper and ink.
For a 200-page black-and-white book on Amazon.com:
| Trim Size | Tier | Printing Cost | Min List Price | Royalty at $12.99 |
|---|---|---|---|---|
| 6" × 9" | Regular | $3.40 | $5.67 | $4.39 |
| 7" × 10" | Large | $4.40 | $7.34 | $3.39 |
| 8.5" × 11" | Large | $4.40 | $7.34 | $3.39 |
The difference is $1.00 per copy on a 200-page book. Over 1,000 sales, that's $1,000 less in your pocket — just from choosing a large trim size when a regular one would have worked. Use the royalty calculator to see the exact impact for your page count and ink type.
How trim size affects page count (and spine width)
The same manuscript will have a different page count depending on the trim size. A 60,000-word novel might be 250 pages at 5" × 8" but only 200 pages at 6" × 9" because the wider page fits more words per line. Fewer pages means a thinner spine, which affects your cover layout.
This matters because KDP doesn't allow spine text on books under 79 pages. If your book is borderline, choosing a smaller trim size increases your page count and might push you above the 79-page threshold — letting you add a title on the spine, which makes your book look more professional on shelves.
After choosing your trim size, use the spine width calculator with your final page count to get the exact spine measurement for your cover.
Trim size and reader expectations
Readers don't consciously think about trim size, but they notice when something feels off. A romance novel printed at 8.5" × 11" feels like a textbook. A business guide printed at 5" × 8" feels like it was designed for a different book. Matching your genre's standard trim size is one of those small details that signals professionalism.
If you're unsure, walk into a bookstore (or browse Amazon's "Look Inside" previews) and check the physical dimensions of top-selling books in your genre. Most product pages list the dimensions in the "Product Details" section.
Hardcover trim sizes
Not all 14 sizes are available for hardcover. KDP hardcover (case laminate) supports 8 trim sizes: 5.5" × 8.5", 6" × 9", 6.14" × 9.21", 6.69" × 9.61", 7" × 10", 7.44" × 9.69", 7.5" × 9.25", and 8.5" × 11". Hardcovers also require a minimum of 75 pages.
If you're planning both a paperback and hardcover edition, choose a trim size that's available for both formats so you can reuse your interior formatting. The cover size guide has the full list of supported sizes for each format.
Quick decision framework
Is it fiction, poetry, or a short memoir? → 5.5" × 8.5"
Is it nonfiction, self-help, or business? → 6" × 9"
Is it a workbook, planner, or coloring book? → 8.5" × 11"
Is it a cookbook or photo book? → 7.5" × 9.25" or 8.25" × 8.25"
Not sure? → 6" × 9" (the safe default for anything)
Related tools
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KDP CoverLab Pro supports all 14 trim sizes. Enter your page count and paper type — we calculate the spine width, bleed zones, and export dimensions automatically.
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