Why Your PDF Interior File Gets Rejected by KDP (And How to Fix It)

When KDP rejects your PDF interior file, the problem is almost always how the PDF was created rather than anything wrong with the format itself. The most common causes are a mismatch between your PDF page size and the trim size you selected during setup, content that falls outside KDP’s required margins, fonts that are not fully embedded, and images below 300 DPI. All of these are fixable in your source file before you re-export to PDF.

How Does KDP Review Your Interior File?

KDP checks your file in two stages. The first is an automated scan by its Print Previewer tool, which runs the moment you upload your manuscript. Print Previewer checks for specific technical problems: page size errors, margin violations, unembedded fonts, and several others. If it finds issues, you will see an explanation of each error and can navigate to the affected pages directly in the previewer.

Print Previewer will attempt to fix certain problems automatically by scaling or reflowing your content to fit within the required margins. This can be helpful, but it also means the tool sometimes catches formatting errors that are not obvious when you look at your manuscript yourself; it is reading the structure of the file, not just what is visible on the page.

The second stage is a manual review that happens after you submit your book for publication. If KDP’s reviewers find additional issues, you will receive an email with links back into Print Previewer showing exactly where the problems are. Understanding what both stages check for makes it much easier to get your file right before uploading.

What Happens When Your PDF Page Size Doesn’t Match the Trim Size?

The page dimensions in your PDF must exactly match the trim size you selected in your KDP book setup. If you chose a 6” × 9” trim and your PDF pages are set to US Letter (8.5” × 11”), Print Previewer will reject the file immediately. This is one of the most straightforward errors to make and to fix.

In Microsoft Word, you set the page size under Layout > Size > More Paper Sizes. Enter the exact width and height that match your chosen trim. If your book uses bleed (meaning images or background colours intentionally extend to the very edge of the printed page), you need to add 0.125” (3.2 mm) to the width and 0.25” (6.4 mm) to the height to account for the extra material that will be trimmed off. Most text-only books do not use bleed, so for the majority of authors the PDF page size should simply match the trim size exactly.

One thing to watch for: changing the page size in your source file will reflow all of your text, which changes your page count. Since KDP’s margin requirements depend on your page count, you may need to adjust your margins after resizing. Always confirm both settings before exporting your final PDF.

Why Is KDP Flagging Content Outside the Margins?

Margin violations are the single most common reason KDP flags an interior file. KDP requires that all text and non-bleeding content sit within a safe area defined by the top, bottom, outside, and inside (gutter) margins. The inside margin is larger than the outside because the binding eats into the page; KDP specifies minimum values for each edge based on your page count and whether or not you are using bleed.

The tricky part is that Print Previewer does not just check for text you can see. It scans for any content outside the margins, including invisible characters. Two situations catch authors off guard regularly. First, italicised text can extend slightly beyond its text box because italic characters lean past their bounding box. If that overshoot crosses the margin line, Print Previewer flags it. Second, trailing spaces at the end of lines can extend invisibly past the margin. The spaces are technically text characters, so the tool treats them as content outside the safe area.

To find these hidden culprits in Word, click the pilcrow button (¶) on the Home ribbon to reveal all formatting marks. You can also press Ctrl + A on a flagged page to highlight every object, which makes stray text boxes and invisible elements visible. If Print Previewer is scaling some pages differently from others, invisible characters or forgotten text boxes are almost always the cause.

What Does “Fonts Not Embedded” Mean?

Embedding a font means storing the complete font data inside your PDF so that KDP’s printing presses can render the text exactly as you designed it. If a font is not embedded, the press has to substitute a different font, which changes your layout in unpredictable ways. KDP requires all fonts to be fully embedded in every interior and cover file.

In Word, go to File > Options > Save, then check “Embed fonts in the file.” Make sure the two sub-options (“Embed only the characters used in the document” and “Do not embed common system fonts”) are both unchecked; partial embedding can cause the same errors. Then save your file as PDF from File > Save As.

There is one edge case that trips people up: some fonts have licence restrictions that prevent commercial embedding. If you have fully embedded your fonts but Print Previewer still shows an unembedded font error, the font’s licence may be blocking it. The fix is to switch to a font that permits embedding. Most standard serif and sans-serif fonts (Garamond, Times New Roman, Georgia, and others commonly used in book interiors) allow full embedding without restrictions.

How Does Image Resolution Affect Your Print File?

KDP recommends that all interior images be at least 300 DPI (dots per inch) at their printed size. An image that looks sharp on screen at 72 or 96 DPI will print blurry because screens and printing presses operate at very different resolutions. If you are unsure whether your images meet the threshold, you can check: right-click the image file, open Properties > Details, note the pixel dimensions, and divide by the size the image will be printed at. A 1200 × 1800 pixel image printed at 4” × 6” is exactly 300 DPI.

Two common workflows silently degrade your images. The first is enlarging an image after inserting it into your document; stretching a 600 × 900 pixel image to fill a full page drops the effective DPI well below 300. Always insert images at their intended print size. The second is Word’s built-in image compression, which is turned on by default. To disable it, go to File > Options > Advanced, find “Image Size and Quality,” and check “Do not compress images in file.” For a deeper look at how DPI works in print books, see our guide to interior image DPI for print-on-demand.

What Other Issues Can Get Your Interior PDF Rejected?

Beyond the big four (trim size, margins, fonts, and images), KDP checks for several other problems that are less common but still cause rejections.

Transparencies and unflattened layers. If you create your PDF in a design application like InDesign or Affinity Publisher, make sure all transparencies and layers are flattened on export. Unflattened layers can cause elements to shift or disappear during KDP’s processing.

Excessive blank pages. KDP allows a maximum of four consecutive blank pages at the beginning or middle of your manuscript, and ten at the end. More than that triggers a rejection.

Pagination errors. Page numbers must run sequentially with even numbers on left-hand pages and odd numbers on right-hand pages (reversed for right-to-left languages). A skip or jump in the sequence suggests missing or misordered pages, which KDP flags as a production risk.

Book details mismatch. The title, author name, and ISBN in your interior file must exactly match what you entered during KDP title setup. Even small differences (such as “J.T. Smith” on the title page versus “John T. Smith” in KDP) will be flagged during manual review.

Template placeholder text. If you used a formatting template, check your front matter, headers, and footers for any placeholder text you forgot to replace. This is caught during manual review and will delay publication.

Frequently Asked Questions

Does KDP accept Word files or only PDFs for print interiors?

KDP accepts both Word (.doc/.docx) and PDF files for print book interiors. However, PDF gives you more control over the final output because KDP does not need to convert or reinterpret your layout. If your book contains images, custom fonts, or any non-standard formatting, PDF is the safer choice.

Will KDP’s Print Previewer fix formatting issues automatically?

Print Previewer will attempt to fix some margin and trim size issues by scaling or reflowing your content. However, this automatic correction can introduce new problems: pages may scale unevenly, text may shift, and your layout may not look the way you intended. It is always better to fix the issues in your source file and re-upload a clean PDF.

Do I need to add bleed to my interior PDF?

Only if your book has images, colours, or design elements that intentionally extend to the very edge of the printed page. Most text-only novels and nonfiction books do not need bleed. If none of your content touches the page edges, set your bleed option to “No Bleed” in KDP and export your PDF at the exact trim size.

What is the minimum font size KDP allows in a print book?

KDP requires that all text be at least 7 points. Text smaller than that will be flagged as illegible during review. This applies to body text, captions, headers, footers, and any text within images.

How do I check whether my fonts are embedded in a finished PDF?

In Adobe Acrobat Reader, open the PDF and go to File > Properties > Fonts. Every font listed should show “Embedded” or “Embedded Subset” next to its name. If any font shows neither, it is not embedded and will need to be fixed in your source file before re-exporting.