Picking Your Trim Size

Choosing the right trim size—the dimensions of your book's pages—is an important design decision to make as a self-published author. It affects how your book looks, feels, is priced, and even how it's perceived by readers. While it might seem like a small detail, trim size plays a big role in your book’s success.

The first step is to look at industry standards for your genre. Here are some common trim sizes:

• Fiction (novels) or Nonfiction (memoirs): 5" x 8", 5.25" x 8", or 6" x 9"

• Nonfiction: 6" x 9", 7" x 10", or 8.5" x 11"

• Children’s books: 8" x 8", 8.5" x 8.5", or 7" x 10"

• Workbooks or manuals: 8.5" x 11"

A smaller size (like 5" x 8") can make a book feel more intimate or portable—great for novels. Larger trim sizes (like 8.5" x 11") are better for visual content, such as guides, planners, or cookbooks.

Trim size affects your page count. A smaller book means fewer words per page, which can increase your total number of pages. More pages can mean higher printing costs and potentially a higher retail price.

On platforms like Amazon KDP or IngramSpark, printing costs are calculated based on page count and trim size. If your book is long, a slightly larger trim size (e.g., 6" x 9") might help reduce costs by fitting more words per page.

Color interiors also play a role in the cost. Black and white interiors are cheaper to produce than color making the printing cost less.

Readers are familiar with certain sizes for certain types of books. A self-help book in a tiny trim size may feel unprofessional. Similarly, a fiction book printed at 8.5" x 11" can look odd and off-putting. Take a trip to a bookstore and measure a few titles in your genre. Emulating those choices helps your book look polished and market-ready.

Trim size affects your layout design and cover appearance. A taller book may feel more bulky, while a smaller one can feel more intimate. If you’re working with a designer, discuss which size will best showcase your content.

Not every trim size is available on every platform. Amazon KDP and IngramSpark both offer a variety of standard sizes, but availability can vary. Always confirm that your chosen size is supported before finalizing your formatting and cover design.

Final Tip: When in doubt, 6" x 9" is the most commonly used trim size for both fiction and nonfiction and is a safe, professional-looking choice for most books.