Free KDP Tools & Calculators
Free interactive tools and calculators for self-published authors formatting books for Amazon KDP. Calculate margins, royalties, spine width, and more.
The book studio: format your book yourself
Upload the Word file you wrote in. Get an Amazon-ready paperback PDF, a Kindle file and both covers, each checked against Amazon’s rules. Look through every page free — pay £29.99 including VAT only when you take the files.
Open the studio →EPUB vs MOBI: What to Upload to KDP in 2026
Interactive comparison of EPUB vs MOBI for Amazon KDP in 2026. Amazon deprecated MOBI for reflowable eBooks in 2021 (and for fixed-layout eBooks in 2025) — find out which format to use with our decision tree and feature comparison.
Use tool →KDP Formatting Checklist — Interactive Pre-Upload Checklist
Interactive KDP formatting checklist you can tick off as you go. Covers interior formatting, cover setup, metadata, and upload steps. Download as PDF when complete.
Use tool →KDP Rejection Reasons: The 15 Most Common, Fixed (Interactive Tool)
The 15 most common KDP rejection reasons and how to fix each one — an interactive tool: pick your reason, get the step-by-step fix. Margins, cover, ISBN, fonts and more.
Use tool →KDP Trim Size Guide — Find the Perfect Size for Your Book
Interactive guide to all Amazon KDP trim sizes. Find which trim size suits your genre with UK-specific examples, bleed options, and a filterable comparison table.
Use tool →White Paper vs Cream Paper for KDP — Visual Comparison Tool
Interactive visual comparison of white and cream paper for Amazon KDP paperbacks. See how text looks on each, compare costs, and find which suits your genre.
Use tool →Word to KDP: How to Format a Word Document for a KDP Paperback, Step by Step
Format a Microsoft Word file for a KDP paperback in 8 clickable steps: page size (Word in the UK starts on A4), KDP's gutter margins by page count, styles, headers, section breaks, contents and PDF export.
Use tool →Additional Tools
ISBN Barcode Generator
Turn your ISBN into a scannable EAN-13 barcode at KDP's suggested size. Free, no sign-up. Download a 100% black vector PDF, an SVG or a 300 PPI PNG.
Use tool →KDP Cover Calculator
Free KDP cover calculator. Enter trim size, page count and paper to get the full paperback cover size in inches, mm and pixels, the spine, safe zones and barcode area, then download a 300 DPI template.
Use tool →KDP Keyword Checker
Amazon lets you add up to seven keywords. Paste yours with your title and this checks them against KDP's own rules: wasted repeats, banned words, quotes and more.
Use tool →Copyright Page Generator
Build the copyright page for your self-published book, written to UK law. Asserts your moral right under the CDPA 1988. Free, runs in your browser, nothing is sent anywhere.
Use tool →KDP Spine Width Calculator
Work out your KDP paperback spine width and full wrap-around cover size from your page count, paper type and trim size — using Amazon's own published multipliers.
Use tool →KDP Royalty Calculator (UK & US): Kindle and Paperback, Free
Free KDP royalty calculator for Amazon.co.uk and Amazon.com. Kindle 35% or 70% after delivery cost, paperback 50% or 60% minus printing, with every rate taken from Amazon's own pages.
Use tool →ISBN Validator & Converter
Validate any ISBN-10 or ISBN-13 check digit instantly. Converts between formats and flags placeholder ISBNs.
Use tool →KDP Margin Calculator
Calculate the exact gutter and outside margins required for your KDP paperback based on page count.
Use tool →Trim Size Visualiser
Compare KDP trim sizes to scale, side by side. All 17 paperback sizes with maximum page counts by paper type, the large-trim threshold that changes your printing cost, and which size suits your genre.
Use tool →Word Count to Page Count Calculator for KDP
Free word count to page count calculator for Amazon KDP paperbacks. Enter your words and trim size to estimate pages and spine width, with how the number is worked out.
Use tool →Free open-source publishing tools
A curated directory of free, open-source tools for writing, formatting and checking your book.
Browse the directory →