Question 1

What does the KDP Cover Validator check?

Accepted Answer

The validator checks: (1) File size is under KDP's 650 MB limit, with 40 MB or less recommended, (2) Resolution is at least 300 DPI for images, (3) Dimensions match your trim size + spine width + 0.125 inches of bleed on every edge, and says so plainly when the bleed is missing, (4) Aspect ratio, (5) Color mode, and (6) The file is a single-page PDF, which is the only format KDP takes for a paperback cover.

Question 2

How accurate is the spine width validation?

Accepted Answer

The validator calculates expected spine width using KDP's thickness factors: 0.002252 inches per page for black-and-white on white paper, 0.0025 for cream paper, 0.002252 for standard color and 0.002347 for premium color. A PDF is measured in inches and must be within 0.03 inches of the expected size; for an image, the spine it implies must match your page count within 5%.

Question 3

What file formats can I validate?

Accepted Answer

KDP only takes a paperback cover as one PDF, so a PDF gets the full check. You can also upload a PNG or JPG of your design to check its size, bleed and DPI before exporting it; the result will remind you it still has to be saved as a PDF.

Question 4

What's the difference between warnings and failures?

Accepted Answer

Failures mean your cover does not meet KDP's minimum requirements and will likely be rejected. Warnings indicate your cover meets minimums but could be improved (e.g., the file is over the 40 MB KDP recommends, or the spine suggests a different page count than you entered).

Question 5

Do I need to enter my book specifications?

Accepted Answer

Yes, you must enter your trim size, page count, and interior type (paper quality) in the left panel. The validator uses these to calculate the expected cover dimensions and validate your uploaded file against them.

Question 6

Does this guarantee KDP will accept my cover?

Accepted Answer

While this tool checks against KDP's published specifications, Amazon may have additional internal checks. Always review your cover in KDP's preview tool and follow any feedback from Amazon's review team.

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