Trim size is the finished size of a printed book after the pages have been cut. It is one of the first decisions in book design, and one of the hardest to change later. Every line of the interior layout, every measurement on the cover and every quote from a printer depends on it.
The good news is that you do not need to invent a size. Most books fit comfortably into a handful of standard formats. The task is to choose the one that suits your genre, your reader and your budget.
Start with your genre
Readers have expectations about how a book should look and feel, even if they have never thought about it. A literary novel that arrives at the size of a cookbook feels wrong before anyone reads a word. So the first question is simple: what do similar books on the shelf look like?
Common starting points for books printed in the United States include:
- 5 x 8 inches for fiction, memoir and poetry, especially shorter books.
- 5.5 x 8.5 inches for fiction and narrative nonfiction. It is slightly roomier than 5 x 8.
- 6 x 9 inches for nonfiction, business books, longer novels and many memoirs. It is the most widely used trade paperback size.
- 7 x 10 inches and 8.5 x 11 inches for workbooks, textbooks, manuals and books with large images or tables.
- Square and landscape formats for children's picture books, photography and art books.
Pull five or six recent books in your genre from a bookstore shelf or your own collection and measure them. That small exercise answers most trim size questions.
Think about the reading experience
Trim size controls how long each line of text can be, and line length has a direct effect on reading comfort. Lines that are too long tire the eye. Lines that are too short break up sentences and make the text feel choppy.
A smaller trim size suits continuous reading: fiction, memoir and narrative nonfiction that a reader holds in one hand for hours. A larger trim size gives room for headings, sidebars, tables, images and generous margins, which suits books that readers consult, annotate or keep open on a desk.
If your book includes illustrations, charts or photographs, look at them at the sizes they would print. An image that reads clearly at 6 x 9 may become hard to read at 5 x 8.
Understand the effect on page count
The same manuscript can produce very different page counts depending on trim size. A 70,000-word novel might run around 280 pages at 6 x 9 and well over 300 at 5 x 8, depending on the typeface, type size and margins.
Page count matters for three reasons:
- Printing cost. Most printers charge partly by page count, so a smaller trim size can make a book more expensive to print.
- Spine width. More pages mean a thicker spine, which changes the cover design.
- Perceived value. Very thin or very thick books can feel out of place in some genres.
Before you commit, use our Words to Pages tool to estimate how long your book will run at different trim sizes.
Check what your printer and platforms support
Not every printer offers every size, and print-on-demand platforms each publish their own list of supported trim sizes. If you plan to distribute through more than one platform, choose a size that all of them support. Otherwise you may end up with two slightly different editions and two sets of files.
Paper and binding options can also vary by trim size. Hardcover editions, for example, are often available in fewer sizes than paperbacks. If a hardcover edition is part of your plan, check its size options before you decide.
Consider the whole series
If this book is the first in a series, the trim size you choose now will likely carry through every book that follows. Readers notice when one volume does not match the others on the shelf. A little extra thought at this stage saves an awkward decision later.
When to break the convention
Sometimes a non-standard size is exactly right. A pocket-sized edition of poetry, a square gift book or an oversized photography book can stand out because of its format. The trade-offs are usually higher printing costs, fewer printer options and less shelf compatibility in bookstores. If the format is part of what makes your book special, those trade-offs can be worth it. Just make the decision deliberately, with quotes in hand.
Trim size checklist
- ☐ Measured five or six comparable books in your genre
- ☐ Considered how readers will use the book (continuous reading or reference)
- ☐ Checked that images, tables and charts remain readable at the chosen size
- ☐ Estimated the page count at your preferred size
- ☐ Confirmed the size is supported by every printer and platform you plan to use
- ☐ Checked hardcover and paper options if you need them
- ☐ Thought about future books in a series
- ☐ Shared the final trim size with your designer before layout begins
Frequently asked questions
What is the most common trim size for a self-published book?
For trade paperbacks in the United States, 6 x 9 inches is the most widely used, followed by 5.5 x 8.5 and 5 x 8 for fiction.
Can I change trim size after the book is designed?
Yes, but it usually means reflowing the entire interior and rebuilding the cover, so it is close to starting the design again. It is far easier to decide early.
Does trim size affect the ebook?
No. Ebooks reflow to fit the reader's screen, so trim size applies only to print editions.
Still deciding?
Trim size is easier to choose with real pages in front of you. If you would like a second opinion, our designers can mock up sample spreads at two or three sizes so you can compare them side by side. Learn more about our book interior design, see how trim size fits into the bigger picture in How to Self-Publish a Book: A Step-by-Step Roadmap, or book a free 30-minute consultation.