Every KDP trim size, explained

A trim size is the final physical dimensions of your printed book after the excess paper has been cut away during manufacturing — hence the name "trim." When you set up a paperback or hardcover on Amazon KDP, one of the first decisions you make is choosing a trim size, because it determines the page dimensions of your interior PDF, the template you use to lay out your cover, and ultimately how your book feels in a reader’s hands.

Choosing the wrong trim size has real consequences. A 6" × 9" manuscript reformatted to 5" × 8" will have different line breaks, different page counts, and potentially awkward chapter endings — requiring a full interior redesign. A cover built for one trim size will not fit another. It is a decision worth getting right the first time, and this hub exists to make that decision easier.

How to choose a trim size

Start with your genre. Non-fiction readers expect 6" × 9" — it is the de-facto trade paperback standard for business books, self-help, memoirs, and how-to guides. Readers associate this size with authority and credibility. Fiction readers are more tolerant of size variation, but 5.5" × 8.5" is the closest KDP equivalent to the trade paperback standard at independent bookshops. Mass-market genre fiction (romance, thriller, cozy mystery) can work well at the smaller 5" × 8" trim.

For journals, notebooks, and low-content books, the 5.06" × 7.81" trim has become the industry standard, with 6" × 9" a common secondary choice for larger journals. Workbooks, activity books, and colouring books typically use 8.5" × 11" or 8" × 10" to maximise page area for activities and response spaces.

Full-color vs black-and-white printing

KDP’s printing cost is split between a base charge and a per-page charge that varies by page area and paper type. Black-and-white interior pages cost approximately $0.012–$0.016 per page depending on trim size. Full-color interior pages cost $0.07–$0.09 per page — roughly 5–7× more. This cost difference is the dominant factor in format selection for illustrated books: a 200-page color book at 8.5" × 11" can cost $16–$18 to print, requiring a retail price of $29.99+ to generate meaningful royalties. Most KDP publishers keep interiors black and white and use a color cover to attract attention — reserving color interiors for children’s books and premium illustrated titles where the visual content is the core value.

The most popular sizes at a glance

If you want the broadest reader recognition and the largest selection of KDP templates, these four sizes cover the vast majority of published titles:

• 6" × 9" — Best all-round choice for non-fiction. Hardcover eligible.
• 5.5" × 8.5" — Trade paperback standard for fiction and literary non-fiction. Hardcover eligible.
• 5.06" × 7.81" — The dominant size for journals, notebooks, and low-content books.
• 8.5" × 11" — Maximum page area — workbooks, activity books, large puzzles.