Why is my file flagged for inconsistent page sizes?

At least one page has different dimensions from the rest. This usually happens when a page or section is pasted in from a document set to another size, and it is one of the more common causes of upload trouble.

Is a warning something I must fix?

Not necessarily. Warnings mark things that are sometimes a problem depending on context, most often image resolution. Read what the warning says about that specific item rather than treating all warnings as errors.

When does a clean result still not mean much?

When the concerns are editorial rather than mechanical. This inspects the structure of a file — its geometry, its embedded resources, its page count — and can say nothing about whether the writing is finished, the metadata is right, or the content meets the rules a human reviewer applies.

Free KDP File Validator

A rejected upload costs you a day. The file goes in, the review comes back, and you are reading an error message about a dimension you cannot see in your PDF viewer. This validator exists to catch the mechanical problems before Amazon does.

It inspects the file itself: page dimensions and whether they are consistent, page count, embedded fonts, image resolution, colour space and whether the document opens cleanly at all. These are the failures that are objectively checkable from the file.

It is deliberate about its limits. A validator can tell you a page is the wrong size. It cannot tell you the cover text sits too close to the trim, that your chapter headings are inconsistent, or that page 143 is upside down. Those need a human and a printed proof.

How to use Free KDP File Validator

Upload the interior PDF you plan to submit, or the cover file if you are checking a wrap.
Wait for the structural scan to finish reading page geometry and embedded resources.
Work through anything reported as an error first, since those are the issues most likely to stop an upload.
Treat warnings as things to look at rather than things that must change.
Fix the file in your layout tool and re-run the check before uploading.

What Free KDP File Validator does

Page size consistency across the whole document
Page count and even-count checking
Embedded font detection
Image resolution sampling
Colour space reporting
Plain-language explanation of each finding

Frequently Asked Questions

Does passing this validator mean KDP will accept my file?

No, and it cannot. This checks the mechanical properties of the file. Amazon also reviews content, rights and metadata, and applies its own review that no third-party tool can predict or guarantee.

What does it actually check?

Properties that can be read from the file itself: page dimensions and their consistency, page count, whether fonts are embedded, image resolution, colour space, and whether the document parses.

What can it not check?

Anything that requires judgement or context. Margin safety against your specific design intent, typographic consistency, image placement, whether the content reads correctly, and anything about your metadata or rights.

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