How to determine your book’s trim size

As going through the self-publishing process, you’ll certainly be asked to set the book’s trim size. This is the final size of a printed page (or the actual size of a book’s page). If you took a ruler and measured the page’s bottom (or top) edge and either its left or right side, you’d have its trim size or the book’s dimensions.

Knowing the trim size is vital. Usually a book is printed on larger paper than what the book will be, and then the pages are cut to their correct size. The trim size tells the printer what measurements to cut the page to – hence the term “trim.”

Books typically are cut to a few specific trim sizes, which aids in the shipping of the books between printer and bookstore. To save on shipping and storage costs, many distributors only handle these standard book sizes. Because of this, many self-publishing companies suggest specific trim sizes for your book.

Among the typical trim sizes in self-publishing are (all measurements are inches):
  • 5 x 8 – Usually the smallest size for a novel
  • 5.5 x 8.5 – Often the largest size for a novel and a common standard size for nonfiction works
  • 6 x 9 – Another common size for a nonfiction book
  • 8 x 10 – Textbook and picture book size

You can go with other sizes than these (this book does), but if a nonstandard trim size, it can limit your sales opportunities. It also can increase your costs as you may need more paper than typical to trim the book to the size you desire.

Sometimes the color paper you select will limit the trim size. Paper with a white background should give you the widest selection of trim sizes.

Bleed area
In addition, you may come across the term “bleed,” a term somewhat related to trim size.

All print presses move slightly as paper passes through it, so sometimes gaps will appear between an image and the paper’s edge, resulting in a blurred picture. To avoid this, images typically don’t end at the paper’s edge but instead extend outside of the page area – in other words, the image will “bleed” off the page.

The measurement for the bleed area is how many inches from the paper’s edge that the image goes off the paper. In the United States, this typically is 1/8 of an inch.