Screen covers: fixed pixel targets
Ebook, audiobook, and platform covers have fixed pixel requirements because they are only ever displayed on screens. Amazon currently describes 2,560 × 1,600 pixels as the ideal Kindle cover and asks for at least 1,000 pixels on the longest side; ACX requires a genuine square of at least 2,400 × 2,400 pixels in RGB; Wattpad tiles use 512 × 800. Design at the full target size — retailers compress and shrink aggressively, and detail that only works at production size disappears in the store grid.
Print covers: inches first, pixels second
A print cover has no single pixel size because the sheet itself changes with the book. The full paperback wrap is two trim widths plus the calculated spine plus bleed, and that physical sheet is exported at 300 DPI. A 6 × 9 inch book on white paper produces a 3,878-pixel-wide wrap at 300 pages and a 3,902-pixel-wide wrap at 336 pages — same design, different books. This is why print files are generated from a calculator rather than downloaded as one-size templates.
The square audiobook problem
An audiobook cover is not a cropped ebook cover. Center-cropping a 1.6:1 portrait into a square usually amputates the composition, and adding borders to preserve the portrait is exactly what ACX rejects. The reliable route is recomposition: keep the artwork, palette, and title system, and rebuild the layout for 1:1 at 2,400 pixels or more.
When the artwork is too small
Pixel requirements are about real detail, not metadata. Upscaling a 600-pixel image to 2,560 pixels produces a soft cover that fails review or looks amateurish in the store. Check the source image's true dimensions before designing, and if the art is too small, replace or regenerate it rather than enlarging it. The free cover check below reads a file's actual pixel size and previews how it survives thumbnail reduction.
Sources: Amazon KDP ebook cover requirements · ACX cover art requirements. Reviewed ; recheck the official page before production.