From the majestic coffee table fixture to the daintiest paperback, books come in all bindings, sizes, and price ranges. Though book sizes may seem arbitrary, it is important to understand why certain industry standards exist. Indeed, presses choose these dimensions for specific reasons. 

If you’re self-publishing and want physical copies, it helps to know about trim sizes. You want to come across as professional as possible. Consequently, it’s a good idea to do your research on typical trim sizes so that readers aren’t dissuaded by a book that is either too large or too small for its length or genre. With a clearer picture, you’ll at least know what you want from a professional formatting and design expert. 

Trim size is publisher-speak for book size using width x height (inches in the U.S., millimeters elsewhere). The “trim” comes from the mechanical page-trimming process. It’s an important factor in cost, marketability, and reader experience.

Trim size and appearance

When you pick a trim size, you’re locking yourself within certain parameters. The trim gives you specific options when you’re typesetting your book, including font size and the baseline grid. Careful choices get you a beautiful book instead of a sardine can of text. If your font size is too large, for instance, your dramatic historical fiction novel may look more like a chapter book. On the other hand, if your font size is too small, readers will be squinting at your words, potentially giving up on reading your book altogether. You want to make sure you’re following industry standards so that your book is as polished as possible.

Page count

When your trim size goes down, your page number goes up—in essence, each page has less space. The more pages, the thicker a book’s spine. It’s why you can tell Les Misérables from Animal Farm a mile away. Page count also relates to how your paper will look in terms of margins and words per page. If your book is particularly long, you will probably want a larger trim; after all, a book that is too thick is difficult to read, and your audience could be turned off.

Cover design

Your cover’s dimensions reflect the trim size. Plenty of people will judge a book by its cover, so it’s something to ponder. A cover specialist can perfect your cover within your trim parameters. 

Industry standards

The market does some of the guesswork for you. The industry has standards in place for different genres. That’s why you’ll notice a general evenness to bookstore shelves. 

Trade paperbacks are the pretty paperbacks that aren’t as wallet-busting as hardcovers. Their sizes run from 5.5” x 8.5” (digest size) to 6” x 9” (U.S. trade size). This size is similar for nonfiction books, fiction books (also sometimes 5” x 8”), and memoirs (sometimes 5.25” x 8”).
Mass-market paperbacks are small and inexpensive. Usually with a trim size of 4.25” x 6.87,” these pop up in the drugstore or Kroger. 

Hardbacks, perfect for showing off your bookshelf (or giving away signed copies as an author!), are usually between 6” x 9” and 8.5” x 11.”

Children’s books are supposed to accommodate little hands and big pictures, so their dimensions are typically 7.5” x 7.5,” 7” x 10,” or 10” x 8.”

Novellas, slim but often written by famous authors, are usually 5” x 8.”

Nonfiction has some of the widest ranges, with 5.5” x 8.5,” 6” x 9,” and 7” x 10” being the most common trim sizes.

Choosing your trim

As a self-publisher, you have to make the call or consult an expert. Aesthetics do play a part, but there are practical things to consider as well. When it comes to trim size, you don’t want to think outside the box. It is best to stick to industry standards. After all, they exist for a reason, and readers expect them. You don’t want to lose potential fans because your book appears unprofessional or unsuitable for its genre.

Word count

The smaller your trim size, the less space per page. You need a book that looks just right both on the page and the shelf. The higher your word count, the more sensible a larger trim size. With a short book, you want a smaller trim size so as to impart some heft and make it noticeable.

Great (genre) expectations

When you get as famous as George R.R. Martin, you can do an “offset printing” for an unconventionally sized book. In the meantime, research the trim sizes in your genre. Especially in fiction, readers often grab the books that look like the last one they couldn’t put down. So, meet your readers’ expectations. You don’t want to confuse them; you want to pull them into the world of your story.

Financial sensibilities 

When you self-publish, trim size impacts your printing expenses. Your book’s size can weigh down on your profit margin since print-on-demand (POD) presses charge according to page count. The trim size can also affect royalties. Some print services give a smaller cut per book the more pages it has. 

Nevertheless, you’re dealing with a tangible object. A super-slim book with a large trim size might not look right or travel well, and it will turn off readers. Physical factors matter, or else they’d just get the eBook. 

Your POD options

While the trim size is your choice, your print service will have its own file specifications. Platforms like KDP have their options listed. Better yet, they have sample chapters so you can see what your layout looks like. 

Now that you understand trim sizes, you can see why so much work goes into crafting your book, even after the writing. If it seems like a lot to handle, a design specialist can help.