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KDP Formatting

How to Create a Paperback Interior for KDP

20 March 2026 11 min read Updated 28 Oct 2026
Checked for accuracy · 23 September 2026

Affinity is free. Corrected against affinity.studio, read 23 September 2026, which states 'Affinity is free for individuals (seriously)' under a heading reading 'Zero bucks given'. Two things changed, not one: Canva merged Affinity Designer, Photo and Publisher into a single app with Vector, Pixel and Layout modes, so 'Affinity Publisher' is no longer a separate product either. This page previously told readers to budget roughly £55 for software that now costs nothing.

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How to Create a Paperback Interior for KDP
KDP Formatting · publishing.co.uk

Last reviewed by Robert Prime — March 2026

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Table of Contents

Introduction

Formatting a paperback for Amazon’s Kindle Direct Publishing (KDP) is often framed as a straightforward, plug-and-play process. Yet anyone who has ventured through the minefield knows the reality is far from it — particularly for UK authors navigating nuances that US-centric guides gloss over. I’m Robert Prime, a UK-based author and digital business veteran with 25+ years in eCommerce and publishing. When I was preparing my own book, Google. Panic. Repeat., writing was the easy bit. The formatting — margins, trim sizes, font embedding, and file conversions — was a marathon of confusion, costly errors, and frustration.

Before building publishing.co.uk, I hired a so-called ’expert’ formatter for £130 who delivered a shambolic file with margin issues and incorrect page numbering. I then tried various automated tools and Fiverr gigs, all of which fell short. This personal struggle is exactly why I created publishing.co.uk — to save UK authors from the same headaches.

This guide is aimed squarely at UK authors looking to self-publish paperback books through KDP. It goes beyond generic advice, delivering practical, business-oriented strategies unique to the UK market. You’ll find detailed cost breakdowns in GBP, ISBN purchasing insights, UK tax considerations, and comparisons with alternative self-publishing and printing options. Most importantly, I share real-world examples from UK authors who have succeeded, along with step-by-step instructions to get your paperback interior perfectly formatted and ready for print.

Paperback interiors: what to know first

Before diving into formatting software or uploading files, it’s critical to understand the landscape, especially from a UK perspective.

Understanding KDP Paperback Formatting

Formatting your book interior means preparing the manuscript file so it prints correctly on KDP’s print-on-demand presses. This involves:

  • Trim Size: The physical dimensions of your book. UK readers traditionally prefer A5 (148 x 210 mm) or 6" x 9" (152 x 229 mm), while US authors often use imperial sizes like 5" x 8". Choosing a size that aligns with UK market expectations is vital for retailer acceptance and reader appeal.
  • Margins and Gutter: Margins are the blank spaces around text to prevent content being cut off or lost in the spine. The gutter is the margin area closest to the binding and must be wide enough to accommodate the spine without swallowing text.
  • Bleed: If your book has images or backgrounds that should run to the edge of the page, you need to set bleed areas, usually 3 mm beyond the trim edges.
  • File Formats: KDP accepts PDF files for print interiors, which is the safest format to preserve layout and fonts. Although Word DOC or DOCX files can be uploaded, they undergo automatic conversion that often causes formatting errors.
  • Fonts: Fonts must be embedded in your PDF to ensure they print correctly. Using standard, licensed fonts reduces the risk of substitution or errors.
  • Page Numbering and Front Matter: Your book must have properly formatted title pages, copyright pages (including your ISBN), and page numbering starting from the first page of the main content. Front matter pages are typically unnumbered or use Roman numerals.

UK ISBNs and Barcodes: What You Need to Know

UK authors can use KDP’s free ISBN or buy their own from the Nielsen ISBN Agency. Here’s what you need to know:

  • Cost: A single ISBN costs £93; a block of 10 ISBNs is £174 (prices as of 2026). Worth buying if you want your own publishing imprint on the book.
  • Free KDP ISBN: Amazon offers free ISBNs, which only work on KDP and show “Independently published” as the imprint.
  • Barcode: UK books use the EAN-13 barcode format. If you provide your own ISBN, KDP will generate a barcode automatically. Alternatively, you can generate one yourself using free online tools.

UK print costs on KDP are influenced by trim size, page count, and whether you print in black & white or colour. These costs are charged in USD and converted to GBP at current rates, meaning fluctuating exchange rates can affect your pricing strategy.

  • A typical 200-page black & white A5 paperback costs a few pounds per copy to print — check KDP’s printing-cost calculator for the current figure, as it varies by page count, trim size and exchange rate.
  • Colour printing costs substantially more than black & white, making it prohibitive for many indie authors.
  • UK VAT rules zero-rate printed books, which is a consideration for pricing your paperback competitively.
  • Setting a retail price that covers print costs, Amazon’s distribution fees, and leaves a reasonable royalty margin is crucial for business sustainability.

Step-by-Step Guide to KDP Paperback Formatting

Below is a detailed, practical walkthrough tailored for UK authors using Microsoft Word — the most accessible tool for self-publishers.

1. Choose Your Trim Size and Page Count

  • Logically, your trim size should reflect what UK readers expect. A5 (148 x 210 mm) is standard for fiction and many non-fiction titles. 6" x 9" (152 x 229 mm) is usually preferred for business books or manuals.
  • Use your manuscript word count to estimate the page count. Roughly, 300 words equate to one page in an A5 paperback format.
  • Plan your trim size early — changing it mid-way causes formatting headaches and affects cover design.

2. Set Up Your Document in Word

  • Open your manuscript in Microsoft Word.
  • Navigate: Layout (or Page Layout) > Size > More Paper Sizes.
  • Enter custom dimensions in millimetres:
    • Width: 148 mm for A5, or 152 mm for 6" x 9"
    • Height: 210 mm for A5, or 229 mm for 6" x 9"
  • Set margins: Layout > Margins > Custom Margins.
    • Top and bottom: 12.7 mm (0.5 inches) is a comfortable, safe margin
    • Inside (gutter): start with 12.7 mm, increase to 15-18 mm for books over 150 pages
    • Outside: 12.7 mm
  • Enable mirror margins to automatically set inside and outside margins for double-sided printing.
  • Set page orientation to Portrait.

3. Format Paragraphs and Styles

  • Open the Home tab, use Styles to define your text:
    • Body text: set to font size 11 or 12 pt, serif fonts like Garamond, Times New Roman, or Georgia work well for readability.
    • Paragraphs: use first-line indent of 6.35 mm (0.25 inches) for fiction. For non-fiction, block paragraphs with spacing (6pt after) may be better.
    • Avoid tabs or multiple spaces to indent — set indents via Paragraph settings > Indentation > Special > First Line.
    • Chapter titles: use Heading 1 style, centre-aligned, larger font size (e.g., 16 pt).

4. Insert Page Numbers and Headers

  • Click Insert > Page Number > Bottom of Page > Plain Number 2 (centre aligned).
  • To start numbering after front matter:
    • Insert a section break after your copyright page: Layout > Breaks > Next Page.
    • Double-click the footer on the first page of main content.
    • Click Link to Previous to unlink from previous section.
    • Format page numbers to start at 1: Insert > Page Number > Format Page Numbers > Start at 1.
  • Optionally, use different headers/footers for odd and even pages: Header & Footer Tools > Design > Different Odd & Even Pages.

5. Add Front and Back Matter

  • Front matter should include:
    • Title page (book title, author name)
    • Copyright page (year, your name, ISBN, publisher info)
    • Dedication or acknowledgements (optional)
  • Back matter might include:
    • About the author
    • List of other books
    • Call to action (e.g., newsletter sign-up)
  • Ensure front matter pages are unnumbered or use Roman numerals (i, ii, iii).

6. Prepare Images and Graphics

  • Images must be at least 300 dpi for quality print.
  • Convert images to CMYK colour mode if possible. Word doesn’t support CMYK natively, so prepare images in Photoshop or Affinity Photo beforehand.
  • Insert images inline and centre them, avoiding wrapping text.
  • Avoid large images which increase file size and may slow upload.

7. Export to PDF

  • Save your document.
  • Navigate File > Save As, choose PDF from the dropdown.
  • Click Options, ensure ISO 19005-1 compliant (PDF/A) is selected.
  • Check that font embedding is enabled (Word does this automatically with PDFs).
  • Open the PDF in Adobe Acrobat Reader or similar and inspect margins, page breaks, and image quality.

8. Upload and Preview on KDP

  • Log into your KDP dashboard (kdp.amazon.co.uk).
  • Select Create Paperback.
  • Upload your manuscript PDF under “Paperback manuscript”.
  • Choose your trim size and paper colour.
  • Upload your cover (front, back, spine) as a PDF or use KDP’s Cover Creator.
  • Use the Print Previewer to check for margin violations, text cut-offs, and gutter issues.
  • Review each page carefully — KDP’s previewer flags common issues but some, like font weirdness, require manual inspection.
  • Order a printed proof copy to review physical quality before final approval.

Paperback interiors in the UK

Trim Size Preferences and Market Expectations

UK bookshops and readers have grown accustomed to metric sizes:

  • A5 (148 x 210 mm) is widely accepted in UK bookstores and libraries.
  • The US paperback size of 5" x 8" (127 x 203 mm) is less common and may stand out awkwardly.
  • For non-fiction or academic texts, 6" x 9" (152 x 229 mm) is preferred.
  • Consistency is key: use metric measurements in your formatting software and cover design to avoid mismatch.

Cost Efficiency for UK Authors

  • KDP’s print cost is calculated in USD then converted to GBP, so the cost you see can fluctuate with exchange rates.
  • Using standard UK trim sizes reduces the risk of printing errors or delays.
  • Ordering proof copies shipped to the UK will incur postage and customs charges; factor this into your timeline and budget.
  • Consider alternative print-on-demand providers with UK-based printers to save on shipping and speed delivery — but weigh this against KDP’s vast distribution reach.

The UK basics, in one place: ISBNs, VAT on books, tax on book income and legal deposit. Those guides are kept up to date, so this page doesn’t repeat them.

Paperback interiors: mistakes to avoid

Even authors with experience stumble on these avoidable issues:

1. Ignoring the Gutter Margin

Too narrow a gutter margin means text or images are swallowed by the spine. I’ve seen authors lose entire sentences because their gutter was only 6 mm when KDP recommends at least 12.7 mm, increasing with page count.

2. Uploading Word Documents Instead of PDFs

While KDP accepts Word files, the internal conversion often mangles formatting — especially indents, headers, and page breaks. Always upload a PDF with embedded fonts and correct margins.

3. Using Non-Embedded or Unlicensed Fonts

Some authors opt for free or decorative fonts without proper embedding. This leads to font substitution, rendering your book unprofessional. Stick to licensed, common fonts and verify font embedding in your PDF.

4. Skimping on ISBN Purchase

Relying on KDP’s free ISBN limits your publishing rights and can cause distribution headaches in the UK and Europe. Investing £93 upfront for your own ISBN is a business decision that pays off in professionalism and control.

5. Overlooking UK Market Expectations

Applying US-centric trim sizes or ignoring VAT rules can cause pricing or distribution issues. UK libraries and retailers often reject books with non-standard sizes or Amazon-listed publishers.

6. Hiring Cheap Formatters Without Vetting

I once hired a formatter for £130 who produced a shambolic file: margins off, page numbering wrong, and image quality poor. It cost me an extra £200 and weeks to fix. Do your due diligence, check portfolios and reviews, or use trusted UK-focused services.

Paperback interiors: tools and resources

Word Processors

  • Microsoft Word: The most accessible and flexible tool for UK authors. Allows custom page sizes, margin settings, and style management.
  • Adobe InDesign: The professional gold standard for layout and design. Expensive and with a steep learning curve, but unparalleled control.
  • Affinity: Free for individuals since Canva took it over, and the cost-effective alternative to InDesign that UK indie authors already liked when it cost money.

Formatting Software and Services

  • publishing.co.uk: An automated formatting service tailored for UK authors. Produces KDP-compliant PDFs aligned with UK sizing and ISBN requirements. Saves hours of frustration.
  • Vellum: Highly praised in the US, but expensive and less UK market-tailored.
  • Scrivener: Best for writing and organising manuscripts; limited for print-ready formatting.

ISBN and Barcode Providers

KDP Resources

  • Amazon KDP Print Guidelines: Essential reading for formatting specs: KDP Print Guidelines.
  • KDP Print Previewer: Use this tool to preview your uploaded interior and cover files before publishing.

Paperback interiors: what it costs

Publishing on KDP is free; what costs money is the help you buy. Every part, with dated sources and a calculator for your own book, is in how much it costs to self-publish a book in the UK.

Paperback interiors by genre

The steps above work for most books, but some genres have their own problems. Each guide below covers one genre, and the second link shows what we do for it.

Frequently Asked Questions

What is the most common mistake UK authors make with KDP paperback formatting?

Ignoring the gutter margin is the biggest mistake. Text too close to the spine is lost in binding. Many also upload Word files directly without converting to a print-ready PDF, causing formatting errors.

How much does KDP paperback formatting cost in the UK?

DIY formatting can be free but time-consuming. Professional formatting services typically range from £150 to £350. ISBNs cost £93 each from Nielsen. Print costs vary — check KDP’s printing-cost calculator for the current per-copy figure.

What tools do UK authors recommend for KDP paperback formatting?

Microsoft Word is the most popular due to its flexibility and availability. Adobe InDesign and Affinity Publisher are preferred by professionals. For hassle-free formatting, many UK authors use publishing.co.uk’s automated service tailored to the UK market.

How long does the KDP paperback formatting process typically take?

Experienced authors can complete formatting in 1-2 days. Beginners should allow a week or more, including proofing and revisions. Hiring professionals can reduce turnaround time to 2-3 days.

Can I handle KDP paperback formatting myself or should I hire a professional?

It’s possible to do it yourself if you have technical patience and attention to detail. However, many UK authors save time and headaches by hiring professionals or using automated UK-specific services.

What are the UK-specific requirements for KDP paperback formatting?

Use metric or UK standard trim sizes like A5 or 6" x 9". Purchase ISBNs from Nielsen to retain rights. Embed all fonts in PDFs. Price books considering UK VAT rules and print costs. Avoid using free KDP ISBNs if you want full control and broader distribution.

Before and After Formatting Example:
Below is a comparison of a poorly formatted versus professionally formatted interior page, highlighting margin errors, inconsistent fonts, and improper page numbering corrected in the professional version.

Robert Prime — Founder of publishing.co.uk

About the Author

Robert Prime

Founder of publishing.co.uk, author of the self-published best-seller Google. Panic. Repeat., co-owner of LoveReading.co.uk, founder of the Amazon agency MrPrime.com and a member of the Forbes Business Council.

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