Free tool
Cover Thumbnail Preview
See exactly how your cover looks at the sizes shoppers actually browse in — not just full-size on your screen.
Drop your cover here, or click to upload
Your image stays in your browser — nothing is uploaded anywhere.
Amazon's standard Kindle ebook cover ratio.
Why does thumbnail size matter?
Most Amazon browsing happens through a grid of small thumbnails, often on a phone screen. A cover that looks stunning full-size on your laptop can become an illegible smear of color once shrunk down — and that's the version most shoppers actually judge before they ever click through to your full listing.
This tool shows you the size — for a full readability, genre-fit, and clickability score, run the Cover Score and get a ranked list of exactly what to fix first.
Frequently asked questions
Why does thumbnail size matter?
Most Amazon browsing happens through small thumbnails, often on a phone — a cover that looks great full-size can become illegible once shrunk down to the size shoppers actually see.
What sizes does this tool show?
Common Amazon display sizes, from small carousel thumbnails up to the full product page image, so you can check readability at each one.
Is this tool free?
Yes, no account needed — just upload your cover image.
Does this check my cover's aspect ratio too?
Yes — it flags if your uploaded image doesn't match your selected trim or ebook cover size's expected aspect ratio.