Most authors pick a trim size by default — usually whatever their formatting software suggests. That works surprisingly often, but the choice deserves five minutes of thought, because changing it later means re-typesetting the interior and redesigning the cover.

Start with what readers expect

Every category has a look. Walk into a bookstore (or open your genre's bestseller list) and measure ten recent books in your category. You will usually find a narrow cluster of sizes:

A book that is far outside its category's norm looks self-published before anyone reads a word. A book that matches the norm signals that it belongs.

Let your word count narrow the options

The same manuscript produces very different page counts depending on the trim. An 80,000-word novel is around 380 pages at 5 x 8 in but about 275 pages at 6 x 9 in (at 11 pt). That difference matters for three reasons:

  1. Print cost. Print-on-demand pricing is largely per page, so a smaller trim can cost more to print.
  2. Spine and heft. Very thin books feel insubstantial; very thick paperbacks are uncomfortable to hold open.
  3. Limits. Most POD services cap paperbacks somewhere around 800–828 pages, and spine text usually needs more than 79 pages.

Use our word count to pages tables to see your manuscript at every size before you decide.

Check what your printer offers

Not every size is available in every binding, paper and ink combination. KDP's standard paperback list includes 5 x 8, 5.25 x 8, 5.5 x 8.5, 6 x 9, 6.14 x 9.21, 7 x 10, 8.5 x 11 and several others, and it allows custom sizes within a range. Its hardcover list is shorter. IngramSpark offers a wider selection, including mass-market and many square and landscape formats. If you plan to distribute through more than one service, choose a size all of them support so both editions match.

Each trim size page on this site lists typical availability — but treat it as a starting point and confirm with the printer.

Think about the interior you need

Text-only books are flexible. Books with tables, diagrams, photos or sidebars need a wider text block, which pushes you toward 7 x 10 in or larger. Poetry needs a measure wide enough for your longest lines without awkward wraps. Workbooks need generous gutters so readers can write near the spine. Large-print editions need a bigger page to keep the page count reasonable at 16–18 pt type.

Plan for every edition at once

If you will publish both paperback and hardcover, choosing a size available in both (such as 5.5 x 8.5, 6 x 9 or 6.14 x 9.21 in) lets you reuse one interior file. Ebooks are reflowable, so trim size does not affect them — but your cover art should be designed so it crops well to the ebook's proportions.

A quick decision checklist

  • Does the size match recent books in my category?
  • Does my manuscript land at a comfortable page count (roughly 150–450 pages for most trade books)?
  • Is the size available in every format and from every printer I plan to use?
  • Does the text block suit my content (images, tables, long lines)?
  • Have I checked print cost at this page count?