Quick answer
The ideal Kindle ebook cover is 2,560 × 1,600 pixels (height × width) — a 1.6:1 ratio, saved as sRGB JPEG. KDP's absolute minimum is 1,000 × 625px, but anything close to that minimum is what usually causes the blur.
If your cover looks soft, pixelated, or slightly stretched on a Kindle — even though Amazon accepted the file without complaint — the cause is almost always one of two things: the image was too small to begin with, or it was the wrong aspect ratio and got stretched to fit. KDP's upload check only blocks files under its minimum size; it doesn't check for actual sharpness, so a technically "valid" file can still look bad to readers.
THE NUMBERS THAT MATTER
IDEAL SIZE
2,560 × 1,600 px (height × width). This is what Amazon recommends for sharp display on high-resolution screens and in the zoomed "Look Inside" preview.
MINIMUM SIZE
1,000 × 625 px. KDP will accept this, but it's the most common reason a cover looks noticeably softer than others on the same shelf.
ASPECT RATIO
1.6 : 1 — height is 1.6× the width. Off-ratio covers get letterboxed with white bars or squeezed to fit, which is the other common cause of a "blurry-looking" cover.
FILE FORMAT
JPEG, sRGB color, under 50 MB. A CMYK (print) color profile will shift your colors dull or flat on screen — always convert to sRGB before exporting.
RIGHT RATIO VS. WRONG RATIO
Both covers below can be "valid" file sizes — but only one matches Amazon's 1.6:1 shape. The other gets forced to fit, which is what actually produces that blurry, slightly-off look, independent of pixel count.
1.6 : 12560 × 1600px renders clean
1 : 1square or off-ratio gets stretched
CHECK YOUR COVER FILEDrop your cover in and instantly see its pixel dimensions, ratio, and whether it matches Amazon's spec.
By far the most common cause isn't a design choice — it's upscaling. A cover gets designed at 800×500px because that's the size of a stock photo or an early draft, then it's stretched up to meet KDP's minimum before upload. Stretching a small image up doesn't add detail back in; it just makes the existing pixels bigger and softer. If you're starting from a small source image, redesign at full size rather than scaling one up — a sharp 1,600px-wide file will always beat an upscaled 2,560px one.
FAQ
What is the ideal Kindle cover size?
2,560 pixels tall by 1,600 pixels wide — a 1.6:1 ratio. That's what Amazon recommends for KDP ebook covers and what keeps a cover sharp on high-resolution screens.
What's the minimum size KDP will actually accept?
1,000 × 625 pixels. It'll upload fine, but that's exactly the size range where covers start looking soft compared to others on the same shelf.
Why does my cover look blurry if Amazon already accepted it?
KDP's upload check only rejects files below the minimum — it never checks for actual sharpness. A cover that was upscaled from something small, over-compressed, or stretched to the wrong ratio will pass the upload and still look blurry to readers.
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