A file that uploads to KDP without an error message isn’t the same as a file that looks right on an actual Kindle. Amazon’s automated checks catch structural problems, not visual ones, a broken table of contents link, a chapter heading that lands mid-page, or curly quotes that render as boxes can all slip straight through. Catching Kindle Previewer errors before you publish is the difference between a clean launch and a stream of one-star reviews about formatting.
What Kindle Previewer Actually Does
Kindle Previewer is Amazon’s own free desktop tool, available for both Windows and Mac. Feed it your manuscript, and it converts the file using the same engine KDP’s actual publishing pipeline uses, then shows you exactly how it will render — across simulated Kindle e-readers, tablets, phones, and the Kindle app, at different screen sizes and orientations.
It accepts the files authors actually have: EPUB, DOCX straight from your word processor, or an existing KPF file. One important thing to understand going in: Kindle Previewer is a viewer and a validator, not an editor. It will show you exactly what’s wrong, but it won’t fix anything. Corrections happen back in your source file Word, Sigil, wherever you’re formatting, and then you reopen the file in Previewer to verify the fix actually worked.
How to Use It: The Basic Workflow
- Download and install Kindle Previewer from Amazon’s KDP site.
- Open your manuscript file. Drag and drop it in, or use File > Open, conversion happens automatically the moment you load the file.
- Check the conversion log. A progress log lists what happened during conversion, and any structural issues — broken links, missing images, table problems, surface here as warnings you can work through one at a time.
- Step through the simulated devices. Preview your book across the different device and screen-size options to see how it actually reflows on each one.
- Fix issues in your source file, not in Previewer. Go back to your DOCX or EPUB, make the correction, and re-save.
- Reopen and reconvert to verify. Previewer resets with each new file load, so you’ll re-check the same spots after every fix until everything comes back clean.
What to Check Page by Page
Once you’re inside the preview, a few spots consistently need closer attention than a quick skim gives them:
- Title page. Does it display correctly at multiple font sizes? Some converters apply unexpected formatting here that isn’t obvious until you actually look.
- Table of contents. Click every single entry. Confirm each one navigates to the correct location, a TOC that looks fine visually can still have broken or mis-linked entries underneath.
- Chapter openings. Check that the first page of every chapter is clean, and that any drop caps, chapter numbers, or decorative elements render the way you intended.
- Symbol encoding. Em dashes, curly quotes, and ellipses are common culprits, these can silently convert into question marks or empty boxes depending on font and encoding settings.
- Images. Confirm they’re JPEG or PNG, inserted as inline images rather than floating text boxes, legible at normal viewing size, and not pixelated.
- Any flagged links. Previewer will surface broken or dead links as warnings. Not every flagged link is actually broken (some intentional dead links in footnotes or citations can still get flagged), but each one is worth a quick manual check.
Common Errors and What Actually Causes Them
A few recurring issues explain most of what shows up in preview:
- Jumbled characters or boxed symbols usually point to an unsupported character or an encoding mismatch, sometimes tied to the language selected in your KDP book details not matching your manuscript’s actual language.
- Inconsistent spacing or indentation is almost always leftover manual formatting (extra paragraph marks, manually inserted tabs) instead of proper paragraph styles doing the work consistently.
- Images that won’t display or look pixelated are typically either not embedded as inline images, too small in their original resolution, or saved in an unsupported format.
- Broken table of contents links usually trace back to a structural navigation problem in the source file itself, not just a visual glitch, this is exactly the kind of thing that looks fine on a casual read-through and only shows up once you actually click through each entry.
This Is a Loop, Not a One-Time Check
Treat Kindle Previewer as a cycle you run every time your source file changes, not a single box to tick before your first upload. Fix an issue, reconvert, verify it’s actually resolved, and check that the fix didn’t introduce a new problem elsewhere. It’s a slower process than a single readthrough, but it’s considerably faster than dealing with formatting complaints after the book is already live and readers are the ones finding the errors.
Formatting problems are some of the most avoidable, and most damaging, issues in a book launch, since they show up in reviews long after the manuscript itself is solid. If you’d like a second pass through Kindle Previewer before you approve your file, our team at Pacific Publishing is glad to help catch anything worth catching. Get in touch and we’ll walk through it with you.