KDP trim size recommender
Publishing glossary
Book trim sizes: the standard KDP sizes and how to choose.
Trim size is the finished page width and height of a printed book after the block is cut. KDP offers a list of standard sizes plus custom sizes within set limits, and the size you pick sets the margins, the print cost, and the spine.
Checked:
✓6x9 inches is the KDP standard✓Page count changes with trim size✓The cover must match the trim size
Standard book trim sizes
Short answer: 6 x 9 in is the most common KDP trim for nonfiction and novels, and 5.5 x 8.5 in is the usual alternative for fiction. The table lists the sizes KDP prints most often, and the ones buyers already recognise on a shelf. KDP also accepts a custom size (width 4 to 8.5 in, height 6 to 11.69 in), but a size off this list has no ready page-count table here, so most authors choose from the list by genre.
| Trim size | Usually used for | Why authors pick it |
|---|---|---|
| 5 x 8 in | Short novels, poetry, novellas | Pocket feel, low page cost per copy |
| 5.25 x 8 in | Literary fiction | Slightly wider text block than 5x8 |
| 5.5 x 8.5 in | Fiction, memoir, trade paperback | The standard trade-fiction proportion |
| 6 x 9 in | Nonfiction, self-help, workbooks | Familiar business-book format, cheap to print |
| 7 x 10 in | Technical books, manuals, textbooks | Room for tables and figures |
| 8 x 10 in | Workbooks, crafts, cookbooks | More space for images and forms |
| 8.5 x 11 in | Coloring books, large-format workbooks | Letter-size pages for art and worksheets |
| 8.5 x 8.5 in | Picture books, square coloring books | Square format children expect |
Choosing a trim size
Fiction usually uses 5x8 or 5.5x8.5, nonfiction and workbooks use 6x9 or larger. The trim size fixes the page dimensions for both interior and cover.
- Pick the size before formatting
- Changing size reflows the whole book
- Trim size sets the spine calculation
Getting the dimensions right
The book sizes tool lists KDP's accepted trim sizes with page counts, and the cover calculator derives the matching wrap from the size you choose.
Why trim is decided before the budget
Every copy of a paperback is cut from a web press sheet, so the trim size fixes the print cost per page and the page-count range Amazon accepts. A 6x9 book at 400 pages and a 5.5x8.5 book at 400 pages have different costs, spines, and royalty outcomes — changing size after formatting reprints the layout and re-runs the budget. Pick size from the page-count tables, then confirm the spine width before you approve the cover file.
- Amazon accepts a page-count range per size, not every size for every count
- Spine text below 80 pages is not recommended for paperback
- Children's books and large-print books use different size sets entirely
FAQ
Frequently asked questions
What are the standard book trim sizes?
For paperback, the sizes you will see most are 5x8, 5.25x8, 5.5x8.5, 6x9, 7x10, 8x10, 8.5x11, and 8.5x8.5 inches. Novels tend to use 5.5x8.5 or 6x9, and workbooks and picture books use the larger sizes.
What is the most common KDP trim size?
6x9 inches for nonfiction and novels, with 5.5x8.5 as a close second for fiction.
Can I change trim size after formatting?
You can, but every page reflows. Choose the size first, then format once.
Does trim size change the spine width?
Not directly. The spine depends on the page count and the paper thickness, but trim size changes how many words fit on a page, so it usually changes the final page count and the spine with it.
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