eBook cover design: what actually sells a book online

Updated 2026-08-22 · 7 min read

Dimensions, typography and genre signalling for covers that survive being 150 pixels wide in a grid.

An eBook cover has one job: make the right reader stop and read the title. It does that job at thumbnail size, on a phone, surrounded by competitors. Every rule below follows from that constraint.

Dimensions and file specs

Aspect ratio 2:3 — the standard for eBook storefronts and reader grids.
1600 × 2400 px is a safe master size; 1000 × 1500 px is the practical minimum.
JPG or PNG, sRGB, under 2 MB so the page stays fast.
Never place text within 5% of any edge — grids and badges crop it.

Typography is the design

Most strong covers are a single image plus two typefaces used decisively. Title large enough to read at 150 px, author name smaller but present, subtitle only if it carries a keyword or a promise.

One display face for the title, one clean face for everything else.
Contrast over decoration — light title on dark image, or the reverse.
Avoid thin weights and tight tracking; both disappear when scaled down.

Signal the genre before you signal your taste

Readers scan for category cues. Literary fiction, romance, thriller, self-help and business books each have a visual language, and matching it is not unoriginality — it is telling the reader the book is for them. Look at the twenty best-selling covers in your category and note what they share, then differentiate inside those constraints.

The five most common mistakes

A busy stock photo with text laid on top of detail.
A title that only reads at full size.
Three or more typefaces.
A cover designed on a large monitor and never checked on a phone.
Wrong aspect ratio, so the cover is cropped or letterboxed everywhere it appears.

Test before you publish

Scale the image to 150 px wide. If you can read the title and guess the genre in one second, it works. Then show it to three people who read your category and ask what kind of book they think it is — not whether they like it.

Writro accepts a cover upload directly in the writing studio, and includes cover templates plus a Writro AI assist for title and blurb copy while you are in there.

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