A trim size is publishing industry jargon that refers to the size of your book. The most common trim sizes for non-fiction books are 5.5 x 8.5 inches or 6 x 9 inches.
Before you-or your publisher-chooses a trim size you should have a clear understanding of the norms for your book’s genre and the requirements of the distribution partners you want to use.
For a more in-depth explanation of trim sizes and how to choose them, I recommend that you read the post from award-winning book designer, Joel Friedlander, entitled “Self-Publishing Basics: How to Pick the Size of your Book.”
Image by: By: Lobsterthermidor at en.wikipedia [CC0], via Wikimedia Commons