Book trim sizes explained: 5×8, 5.5×8.5, 6×9 and the rest
The sizes you will actually choose between
Print-on-demand services offer a long list of trim sizes, but almost every novel, memoir and business book uses one of seven. They have names from the trade that you will see on printer sites and in cover templates.
| Trim size | Trade name | Typical use |
|---|---|---|
| 5 × 8 in | Short novels, poetry, novellas. The smallest common size; thicker spine for the same words. | |
| 5.06 × 7.81 in | B-format (198 × 129 mm) | The standard UK and Commonwealth paperback. Pick this if your readers are mostly in Britain, Ireland, Australia. |
| 5.25 × 8 in | A US paperback size between 5×8 and 5.5×8.5. Popular for genre fiction. | |
| 5.5 × 8.5 in | Digest | Literary fiction, memoir, general non-fiction. Half a US Letter sheet. Feels like a traditional trade paperback. |
| 6 × 9 in | US Trade | The default for print-on-demand. Non-fiction, business, thicker novels, anything with images. Fewest pages for a given word count. |
| 6.14 × 9.21 in | Royal (234 × 156 mm) | The UK hardback and large-paperback size. Non-fiction and literary hardcovers. |
| 7 × 10 in | Textbooks, workbooks, cookbooks, technical books with code or tables. Too wide for a comfortable single column of prose. |
How to choose
Look at the shelf. Find three books in your genre that you admire, and measure them. Readers have expectations they cannot name: a 6×9 thriller feels like a non-fiction book, a 5×8 business book feels slight. Matching the shelf is the safest choice.
Think about the page count. A long book at a small trim size becomes thick and hard to hold open. A short book at 6×9 becomes a thin pamphlet with a spine too narrow for a title. As a rule of thumb, at 11-point type with normal margins a 6×9 page holds about 300 to 350 words, a 5.5×8.5 page about 250 to 300, and a 5×8 page about 220 to 260. A 90,000-word novel is roughly 280 pages at 6×9 and 340 at 5.5×8.5.
Price it. Print-on-demand printers charge per page, so fewer pages means a lower print cost and more room in the royalty. That is the practical reason 6×9 dominates self-publishing. A larger trim also lets you keep a comfortable line length with wider margins.
Decide on the hardcover now. If you want a hardcover edition later, pick a trim size that is available in both bindings so the interior file can be reused. On KDP that means 5.5×8.5, 6×9, 6.14×9.21 or 7×10.
Check both printers. If you plan to distribute through IngramSpark as well as KDP, use a size that both offer. All seven above are safe.
What the trim size changes
- Margins. The inside margin has to grow with the page count so text does not vanish into the spine. A smaller trim leaves less room for text after the margins are taken out, so line length and type size have to be balanced more carefully. See margins, gutter and bleed.
- The cover. A print cover is one wide image: back, spine and front, plus bleed. Its dimensions come from the trim size and the page count, so a cover designer needs both before starting. See cover dimensions and spine width.
- The ebook. Not at all. An EPUB has no pages, and the reader chooses the type size, so the trim size is a print-only decision.
Trim size versus bleed size
If a page has an image or a colored background that runs to the edge, the file has to be slightly larger than the trim so the cut lands inside the printed area. KDP asks for 0.125 in on the three outer edges, which makes a 6×9 file 6.125×9.25. Books that are text only do not need bleed, and the file is exactly the trim size. Do not add bleed "just in case": a text-only file with bleed dimensions will be rejected or will print with the text shifted.
Questions
What is the most common trim size for a novel?
In the United States, 6×9 inches (US Trade) for print-on-demand, and 5.5×8.5 or 5.25×8 for a smaller, more traditional paperback feel. In the UK and Commonwealth, 5.06×7.81 inches, the B-format, is the standard paperback.
Can I change the trim size after the book is written?
Yes, as long as the text is not tied to a fixed layout. In a book app the text reflows and the page count changes. In a word processor you will need to re-check every page break and the table of contents. Change it before you order a cover, because the cover size depends on the trim and on the page count.
Which trim sizes can be hardcovers on KDP?
KDP prints hardcovers in a shorter list of sizes than paperbacks. 5.5×8.5, 6×9, 6.14×9.21 and 7×10 are available as both. Check KDP’s current list before you decide, since it changes over time.
Does the trim size change the words per page?
Yes, a lot. The same manuscript at the same type size runs roughly a fifth shorter at 6×9 than at 5.5×8.5, which changes the page count, the spine width and the print cost. Pick the trim size first, then set the type.