Understanding Trim Sizes and Formats: What Works Best for Your Book?

🚨 Before we begin, don’t forget to follow my blog at The Book Kahuna Chronicles for more behind-the-scenes publishing insights from a 40-year industry veteran. Whether you are a new author or a seasoned pro, I have the tools and tips you need to take your book to the next level. 🚨

When it comes to publishing your book, there is a lot of talk about editing, cover design, and marketing—but trim size and format? That is where I see many first-time authors draw a complete blank.

Recently, I sent out a survey to aspiring first-time authors asking: “What’s keeping you up at night about your publishing journey?” One of the most common answers—right after “how do I market this thing?”—was: “How do I know what size or format my book should be?”

Let me tell you something: if you have asked that question, you are already ahead of the game. Because too many authors never ask at all—and that’s where things start to unravel.

The Publishing Equivalent of the Tailor’s Tape

Think of trim size as your book’s suit of clothes. Just like a well-cut blazer can make you look like a million bucks—or a bad one can make you look like you borrowed it from your uncle—your trim size and interior format can make or break your book’s shelf appeal, readability, and even your profits.

Having worked with publishers big and small for over 40 years, I have seen how choosing the wrong trim size can jack up print costs, alienate readers, and make your book stick out in all the wrong ways.

Let us break this down and demystify the process once and for all.

What Is Trim Size, Anyway?

Trim size refers to the final dimensions of your book after it has been printed and cut—hence the word “trim.” In simple terms, it is the height and width of the finished product. Common sizes you have probably seen on your bookshelf include:

• 5” x 8”
• 5.5” x 8.5”
• 6” x 9”
• 8.5” x 11”

These numbers matter, and here is why: trim size affects the number of pages, your printing cost, your layout design, and how your book is perceived in the marketplace.

Let us start with how it affects cost.

Print Economics: More Than Just Ink and Paper

Here is something many new authors do not know: Trim size directly affects your page count, and your page count affects your print cost.

Take two versions of the same book—one at 5” x 8” and another at 6” x 9”. The 6” x 9” version has more words per page, which means fewer pages overall. Fewer pages = lower print cost = more profit per copy.

This is especially critical if you are using print-on-demand services like IngramSpark or Amazon KDP. If you choose a smaller trim size and your book ends up over 400 pages, you are not just paying more—you might also price yourself out of your target market.

It is a balancing act between aesthetic appeal, genre expectations, and cost efficiency.

Trim Sizes by Genre: The Unwritten Rules

Certain trim sizes have become standard for certain genres, and deviating too far from the norm can confuse readers—or worse, make your book look self-published in the worst sense of the word.

Here is a cheat sheet I have put together based on decades in the trenches:

Genre	Common Trim Sizes
Fiction (novels)	5” x 8”, 5.5” x 8.5”, 6” x 9”
Memoir	5.5” x 8.5”, 6” x 9”
Nonfiction (general)	6” x 9”, 7” x 10”
Business/Self-Help	5.5” x 8.5”, 6” x 9”
Children’s Books	8” x 8”, 8.5” x 11”
Workbooks/Manuals	8.5” x 11”
Academic/Textbooks	6” x 9”, 7” x 10”, 8.5” x 11”

Stick to what your readers expect. If they are used to a 6” x 9” business book and yours comes in at 5” x 8”, it might look more like a pocket-sized pamphlet than a guide to financial freedom.

Trust me—perception is everything.

The Format Decision: Paperback, Hardcover, or eBook?

Trim size is only part of the equation. Do you also need to decide on the format of your book: Paperback? Hardcover? eBook? All three?

Let us walk through your options.

1. Paperback

• Most economical to print.
• Widely accepted across all retail platforms.
• Great for first-time authors.
• Recommended trim sizes: 5” x 8”, 5.5” x 8.5”, or 6” x 9”.

Pro Tip: If you are using Amazon KDP, your trim options will be somewhat limited. Stick with industry standards to avoid headaches during setup.

2. Hardcover

• Adds perceived value.
• Higher production costs.
• Not always available on all POD platforms.
• Ideal for nonfiction, memoirs, or special editions.

Do not go hardcover just because it feels “more professional.” Go hardcover if your audience expects it—or you can justify a premium price.

3. eBook

• No trim size in the traditional sense, but layout still matters.
• Use reflowable text formats (EPUB or MOBI).
• Avoid fancy design elements that will not convert well to digital.

Remember: Your eBook may not mirror your print design exactly—and that is okay. They serve different functions.

Interior Formatting: How Trim Size Influences Layout

Trim size determines more than just outer appearance—it shapes your interior layout:

• Margins: Smaller trim sizes = tighter margins = potential readability issues.
• Font Size: Bigger books allow for a more spacious reading experience.
• Line Spacing and Leading: These affect readability and page count.
• Images/Tables: If your book contains visuals, you will need more horizontal and vertical space—go bigger (8.5” x 11”) to prevent awkward compression.

One of the survey respondents wrote: “I want my book to be as clean and elegant as the books I see at Barnes & Noble—but I don’t know how to get there.”

The answer? You start with the right trim size, and you format with the reader in mind.

Case Studies from the Publishing Trenches

Let me give you a few real-world examples from my career:

Case 1: The Memoir That Looked Like a Phone Book

We had an author submit a 450-page manuscript and insist on a 5” x 8” trim. The result? A brick. Too many pages. Too bulky. Too expensive. We reformatted it to 6” x 9” and cut the page count by 100—resulting in a cleaner layout, lower cost, and better reader experience.

Case 2: The Children’s Book That Missed the Mark

An author went with a 6” x 9” trim for a picture-heavy children’s book. Problem? That is a novel trim, not a kids’ book trim. We switched to 8” x 10”, used full-bleed spreads, and the book suddenly looked like it belonged on the shelves next to Dr. Seuss.

Case 3: The Business Author Who Got It Just Right

This author asked all the right questions: “What do my competitors use?” “What will feel substantial in the hand?” He went with a 5.5” x 8.5” paperback for portability, a matching hardcover edition for speaking engagements, and an eBook for Kindle users. The result? Professional from every angle.

Ask Yourself These Questions Before Choosing a Trim Size

1. What is your genre?
2. Who is your audience?
3. What are comparable books doing?
4. Will this size work well with your content?
5. Do you plan to distribute via POD, offset printing, or both?
6. What is your budget for production and printing?

If you can answer those six questions clearly, you are well on your way to picking the right trim size and format.

Tools and Resources to Make It Easier

• Amazon KDP Trim Size Guidelines
  A comprehensive list of acceptable trim sizes and bleed requirements.
• IngramSpark Print & Trim Guide
  Details on print formats, spine widths, and paper choices.
• Adobe InDesign Templates
  Pre-set files for common trim sizes that can save hours of frustration.
• Reedsy Book Editor
  A free online tool to format your book based on selected trim sizes.

Final Thoughts: Do not Let Trim Size Trip You Up

Listen, publishing is not easy—but it is also not rocket science. Choosing a trim size is just one piece of a larger puzzle, but it is one that affects everything downstream: cost, design, perception, and success.

If you treat your book like a professional product, readers will treat you like a professional author.

Do not cut corners. Do not guess. Do your research, talk to publishing professionals (like me), and approach this process with the respect it deserves.

📣 Want more insider publishing advice like this? Follow me at The Book Kahuna Chronicles and join a growing tribe of authors who are turning their publishing dreams into reality—one smart decision at a time.

Let us keep moving forward—one trim size at a time.

— Don “The Book Kahuna” Schmidt
Masters in Publishing Science, Pace University
40 Years in the Book Business and Still Going Strong