Trim Size Comparator

Compare book sizes side by side. See dimensions, bleed zones, spine width, and cover specs for every KDP trim size — all at a glance.

Start Comparing
10 Trim Sizes Visual Comparison KDP Specs Included 100% Free

How It Works

Three steps to find your perfect trim size

1

Select Sizes

Pick the trim sizes you want to compare from the grid below.

2

Compare Visually

See books drawn to scale, side by side or overlaid on top of each other.

3

Get Full Specs

View dimensions, bleed, spine width, and cover sizes in a detailed table.

Trim Size Comparator

Select trim sizes to compare them visually and get full specs

Select Trim Sizes
Visual Comparison
Select at least one trim size above to see the comparison
Spine Width Calculator
Spine Width (inches)
0.4504"
Spine Width (mm)
11.44 mm
Detailed Specifications
Trim Size Inches mm Pixels @300 DPI With Bleed Front Cover Full Wrap Cover Recommended For

Select trim sizes above to see the specs table.

KDP Margin Reference

24 – 150 pages0.375" gutter
151 – 300 pages0.5" gutter
301 – 500 pages0.625" gutter
501 – 700 pages0.75" gutter
701 – 828 pages0.875" gutter
Outside margins (all)0.25" minimum

Why Use This Tool

Everything you need to choose the right trim size

Visual Scale Comparison

See how trim sizes compare at true proportions. Side-by-side and overlay views make differences immediately obvious.

Complete KDP Specs

Dimensions in inches, mm, and pixels at 300 DPI with bleed calculations. Everything you need for your book files.

Spine Width Calculator

Calculate spine thickness based on page count and paper type. Essential for cover design and KDP uploads.

Cover Dimensions

Get front cover and full wrap dimensions for any trim size. Automatically updated when you change the spine width.

How to Choose the Right Trim Size for Your Book

Trim size is one of the most important decisions when publishing a book on Amazon KDP. It affects readability, production cost, shelf presence, and how your book feels in a reader's hands. The most popular sizes for novels and non-fiction are 5.5 × 8.5" and 6 × 9", while activity books, coloring books, and workbooks typically use 8.5 × 11" (US Letter). Square formats like 8.5 × 8.5" are a great choice for children's picture books.

Use the comparator above to visualize the differences between sizes before you commit. Seeing them side by side at true scale removes all guesswork and helps you pick the format that best suits your content and audience.

Frequently Asked Questions

What is the most popular KDP trim size?
6 × 9" is the most common trim size for novels and non-fiction on Amazon KDP. It offers a good balance between readability and production cost. For activity and coloring books, 8.5 × 11" (US Letter) is the standard choice.
What is bleed and why does it matter?
Bleed is the 0.125" extra area added around each edge of the page that gets trimmed during printing. If your design has images or colors that extend to the page edge, they must extend into the bleed area to avoid white borders after trimming.
How is spine width calculated?
Spine width depends on the number of pages and the paper type. White paper uses 0.002252" per page, while cream paper uses 0.0025" per page. For example, a 200-page book on white paper has a spine width of about 0.45".
What are the minimum margins for KDP?
Outside margins must be at least 0.25" on all sides. Inside (gutter) margins depend on page count: 0.375" for 24–150 pages, increasing to 0.875" for 701–828 pages. These minimums ensure text stays readable near the spine.
Can I use A4 or A5 sizes on KDP?
Yes, Amazon KDP supports international sizes including A4 (210 × 297 mm) and A5 (148 × 210 mm). Availability may vary by marketplace, so check the current KDP guidelines for your target markets.

Build your entire book with Univers Studio

From trim size selection to cover design, interior layout, and publishing — everything you need in one place.

See All Tools