Book trim sizes
Every paperback size Amazon KDP offers, what each one is actually used for, and the three things the choice decides: how the book feels, how many pages it runs to, and what it costs you per copy.
Checked against the published specifications on 2026-10-17.
The trim size is the size of the finished page, after the printed sheet has been cut. It is the first decision in a book’s design because everything else follows from it: the measure, the type size, the page count, the spine width, and the price Amazon will let you charge.
It is also effectively permanent. Amazon treats the trim size of a live paperback as fixed, so changing it later means a new edition with a new ISBN and a new listing.
The standard sizes
These are the five Amazon lists first, and between them they cover almost all fiction and most short non-fiction.
| Trim | Metric | What it is for |
|---|---|---|
| 5" × 8" | 12.7 x 20.32 cm | Compact mass-market feel. Common for poetry, novellas and pocket non-fiction. |
| 5.06" × 7.81" | 12.85 x 19.84 cm | Close to a traditional mass-market paperback. |
| 5.25" × 8" | 13.34 x 20.32 cm | A slightly wider 5 × 8; a little more room per line. |
| 5.5" × 8.5" | 13.97 x 21.59 cm | The usual choice for memoir and short non-fiction. Fewer pages than 5 × 8. |
| 6" × 9" | 15.24 x 22.86 cm | The most common trade paperback size in the United States. The safe default. |
The large sizes
Everything above 6″ × 9″, plus the square and landscape formats. These are for books with something on the page besides prose (diagrams, photographs, exercises, recipes) and for anything printed to be written in.
| Trim | Metric | What it is for |
|---|---|---|
| 6.14" × 9.21" | 15.6 x 23.39 cm | A whisker larger than 6 × 9; occasionally used for academic titles. |
| 6.69" × 9.61" | 16.99 x 24.41 cm | Roughly European B5. Textbooks and manuals. |
| 7" × 10" | 17.78 x 25.4 cm | Workbooks, cookbooks, anything with diagrams beside the text. |
| 7.44" × 9.69" | 18.9 x 24.61 cm | An academic press size. |
| 7.5" × 9.25" | 19.05 x 23.5 cm | Technical and reference titles. |
| 8" × 10" | 20.32 x 25.4 cm | Large-format non-fiction, photo-led books, children's picture books. |
| 8.25" × 6" | 20.96 x 15.24 cm | Landscape. Picture books and photo collections. |
| 8.25" × 8.25" | 20.96 x 20.96 cm | Square. Children's books and art books. |
| 8.5" × 8.5" | 21.59 x 21.59 cm | The larger square. |
| 8.5" × 11" | 21.59 x 27.94 cm | US Letter. Workbooks, journals, manuals, anything printed to be written in. |
| 8.27" × 11.69" (A4) | 21 x 29.7 cm | A4. Note that KDP caps this one at 590 pages in premium colour, and does not offer standard colour for it at all. |
How to choose
The honest answer for most books is 6″ × 9″, and the reason is not that it is best. It is that it is unremarkable. A reader who picks up a 6 × 9 paperback does not think about the format at all, which is what you want. Deviate when you have a reason.
- Fiction, any length. 6″ × 9″, 5.5″ × 8.5″ or 5″ × 8″. Smaller trims feel more like a novel and run to more pages; at 5″ × 8″ expect roughly 30–40% more pages than the same text at 6″ × 9″.
- Memoir and essays. 5.5″ × 8.5″ is the convention and it is a good one: slightly more intimate than 6 × 9 without being pocket-sized.
- Business and self-help. 6″ × 9″, almost always. It is what the shelf looks like.
- Poetry. 5″ × 8″ or 5.5″ × 8.5″. Verse keeps its own line breaks, so a wide measure leaves the right-hand side of the page empty.
- Workbooks, journals, planners. 8.5″ × 11″. It is US Letter, it takes a handwritten answer, and it lies flat enough to write on.
- Photography and children’s picture books. The square formats (8.25″ × 8.25″, 8.5″ × 8.5″) or the landscape 8.25″ × 6″.
What the trim does to your page count
A smaller page holds fewer words, so it takes more pages. That matters for three reasons at once: Amazon’s printing cost rises with the page count, the inside margin requirement rises in bands as the book thickens, and a book over a certain length cannot be printed at all.
| Page count | Minimum inside margin |
|---|---|
| 24–150 | 0.375″ (9.6 mm) |
| 151–300 | 0.5″ (12.7 mm) |
| 301–500 | 0.625″ (15.9 mm) |
| 501–700 | 0.75″ (19.1 mm) |
| 701–828 | 0.875″ (22.3 mm) |
The minimum page count is 24. The maximum depends on the paper and the ink, because a thicker sheet makes a thicker book:
| Paper and ink | Maximum pages |
|---|---|
| Black ink, white paper | 828 |
| Black ink, cream paper | 776 |
| Black ink, groundwood paper | 812 |
| Standard colour, white paper | 600 |
| Premium colour, white paper | 828 |
Bleed, and whether you need it
Bleed is extra image area outside the trim, so that when the sheet is cut, which is never done perfectly, no white edge appears. You need it only if something is meant to run off the edge of the page: a full-page photograph, a coloured background, a rule that touches the margin. A book of prose does not need bleed and should not declare it.
With bleed, Amazon asks for 0.125″ (3.2 mm) on all sides, and raises the outside, top and bottom minimums from 0.25″ to 0.375″. Those numbers are on the print-ready PDF page with the rest of the specification.
Questions
- What is the most common book size?
- 6″ × 9″ (15.24 × 22.86 cm) is the standard trade paperback in the United States and the default on KDP. For fiction, 5.5″ × 8.5″ and 5″ × 8″ are also very common; 5″ × 8″ makes a book that feels smaller and runs to more pages.
- Does the trim size change what the book costs to print?
- Yes, twice over. Amazon's printing cost has a fixed element and a per-page element, so a smaller trim, which fits fewer words on a page and therefore runs longer, costs more per copy than the page count alone suggests. A larger trim reduces the page count but raises the fixed element.
- Can I change the trim size after publishing?
- Not on an existing paperback listing: Amazon treats the trim size as fixed once the book is live, because the printed object is different. You would publish a new edition. Choosing deliberately the first time is worth the ten minutes.
- What trim size should a poetry collection be?
- Something narrow, usually 5″ × 8″ or 5.5″ × 8.5″. Verse is set with its own line breaks and a wide measure leaves most of the page empty, which reads as a mistake rather than as space.
- Is 8.5″ × 11″ a sensible book size?
- For a workbook, a journal, a manual or anything printed to be written in, yes: it is US Letter and it behaves like a document. For prose it is not: the line length at that width is roughly twice what anyone can read comfortably, and the only fix is two columns, which a novel cannot use.
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