Self-Publishing DIY Guideline – Trims, Bleeds, and Margins

I’ve published several children’s books on Amazon via Kindle Direct Publishing (KDP), one of the largest self-publishing platforms available today, and one thing I struggled with initially when first going into self-publishing was understanding exactly how my trim options affected how I should prepare my files, as well as what to take into account for images that I wanted to “bleed” to the edge of the page. In this post I describe some of the things to watch out for. These guidelines are specifically for KDP but should generally apply to other self-publishing platforms as well.

First, some definitions:

  • Trim:¬†The “Trim” is the size of the paper in the end product.
  • Bleed: The term “bleed” is used for colors or images that extend all the way to the edge of the page.
  • Margin: This is the the amount of space you should keep between your content and the edges of your pages.


Different self-publishing platforms offer various trim sizes you can select for your book (click here to check out Amazon KPD’s trim options). Trim sizes are expressed as width by height. There are some standard trim sizes, like 8.5″ x 11″ which is very similar¬†to the well known A4 size (that’s what you typically use to print standard documents) but is actually a bit larger (A4 is 8.27″ x 11.69″). Another common trim size is 6″ x 9″, which is the most common size for traditional paperbacks in the US. However 6″ x 9″ may be too small for children’s books, which will typically be a bit larger.

My favorite trim sizes are 8.5″ x 8.5″, which is a large versatile square, and 8.5″ x 11″. Another cool option is 8.25″ x 6″ which, although it’s a bit small, can be suitable for books that requires a landscape aspect ratio.

What you choose is completely up to you, but it should be something you decide at the BEGINNING of your project. Think about how you want to organize the images and text on your pages so that you can obtain illustrations that fit your desired trim.


My first book which I made with Adobe InDesign was meant to be 8.5″ x 8.5″. I made sure to select that size for my pages and carefully placed all my work into the pages, going all the way to the edges given that my intent was to have bleed (i.e. images were meant to go all the way to the edges of the pages).

Once I was finished with my file, I opened up KDP, got to the content section, selected that I wanted “bleed” and uploaded my manuscript. I waited patiently (it can take a few minutes for a large file with lots of images) and then opened up the preview, which barraged me with warnings about the pages not being large enough to account for bleed.

You see, the way bleed works is they will print your content on a LARGER trim size than what you select, and then cut the paper to match your selected trim size. This way the printer can ensure that your content correctly goes all the way to the edge of the paper, just as you wanted. What it means for you is that you have to use make your content a bit larger than the final trim size in order to account for what gets cut off. This is the margin you need to account for on the outer edges even when your book’s images bleed to the edges. The amount you need to add for outer margin is 0.125″ on each side. You don’t have to take into account the inner edge (i.e. the edge that’s connected to the spine), so you’re adding 0.125″ to the width and 0.25″ to the height (for the top and bottom). This means that your 8.5″ x 8.5″ book will have pages that are 8.625″ in width and 8.75″ in height. When open, it would be 17.25″ in width (which is 8.5″ + 8.5″ + 0.125″ + 0.125″) by 8.75″ in height (8.5″ + 0.25″).

After you figure out the right page size for your files, make sure you actually extend images and colors all the way to the edges, but do remember that 0.125″ of content will be cut off the sides, so don’t put essential content (particularly text) in those areas.

Here’s an image of what that looks like. The yellow parts are the bleed

Self-publishing: Sizes required when using bleed for an 8.5" x 8.5" trim

And here’s an example from my book Dreams of Monsters ABC¬†(the process for writing this book is also detailed in a separate post) which shows what it might look like with the content inserted (note the images go all the way to the edges, but important content such as the text or some of the visual elements like the moon and the face of the Bogeyman are still inside the boundaries):

Self-publishing: Margins are important when using bleed


The inside margin (also known as “gutter”) margin is applicable for all books regardless of whether you are using bleed or not. This is the amount of space that you need to leave between your pages and the inner edge (the one that connects to the spine) of the book. This margin depends on the number of pages in your book. Why? Open up a book that has a lot of pages and you’ll understand why – the larger the book the more the content should be separated from the spine in order to be visible when the reader opens your book. So if you submit your book to KDP and receive an error that says “Interior – Your manuscript content extends past the margins. Margins prevent your content from getting cut off when your book is printed” then make note of “Interior” as it is referring to your gutter margin’s being too small. Push content on the inner edges of your pages outwards and re-submit.


When self-publishing, it’s important to understand trims, bleeds, and margins and planning your content ahead of time will save you headaches when you go to publishing your book. The time you spend planning will ensure that you get a higher quality output in the end.