Choose a cover that survives every handoff.

A good source image matters, but a valid package declaration matters just as much. This guide covers both.

Practical cover dimensions

For a general-purpose ebook cover, 1600 × 2560 px is a useful starting point. Use the largest clean source available and avoid enlarging a small image just to reach a target number.

Fit or crop?

Fit keeps the whole image visible and may add borders. Crop to fill covers the entire target area but can remove content near the edges. Stretching is available only as an advanced option because it changes proportions.

EPUB 2 and EPUB 3

EPUB 3 marks the manifest image item with properties="cover-image". EPUB 2 commonly points to a manifest id with <meta name="cover" content="…" />. Older files can also reference a cover page in the guide.

Reader caches

An updated EPUB can be valid while a reading app still displays an older thumbnail. Remove the previous imported copy before adding the new file again.