Legibility, and the readers you are leaving out
Designers look at covers at full size, on a good screen, in a quiet room, already knowing what the title says. Readers do none of that. They look at a 160-pixel image on a phone held at arm's length, outdoors, at the end of a long day, while deciding whether to keep scrolling.
That is not an edge case to accommodate afterwards. It is the ordinary viewing condition, and designing for it is the same work as designing for a reader with low vision. You are not building a special version for a minority — you are building the version that works for everyone at the moment it matters.
The failures are always the same five
Thin type over a photograph. A hairline or light weight has almost no ink holding it together, and a photograph underneath it changes lightness every few pixels. The letters break up into fragments. This is the single most common unreadable cover.
A light weight at small size. Type that reads beautifully at 400 px thins out and disappears at 160. Weight and size are not independent — the smaller the display, the heavier the face has to be.
A color pair that separates on a bright screen and merges on a dim one. Two colors of similar lightness pull apart on a phone at full brightness in a dark room, and collapse into one tone on the same phone at 20% in daylight. You saw it work. Your reader saw it fail.
Type in the busy part of the image. A title laid across detail has to compete with edges the artwork already put there. Reserve a quiet region for it — Composition and negative space covers how.
Gray on gray. Subtitles, series lines and author names set in a soft gray on a soft ground look elegant on a monitor and vanish everywhere else. If a line is worth putting on the cover, it is worth making readable.
Three views, and none of them cost anything
View it small. Shrink it to thumbnail and look at it cold — The thumbnail test.
View it on a phone, outdoors. Brightness, glare and a smaller physical size are three problems stacked on each other, and no amount of squinting at a desktop monitor reproduces them. Walk outside with the file.
View it in grayscale. Stripping the color out leaves only lightness, which is what legibility rests on. If the title still leaps out, the contrast was real. If it sinks, you were leaning on color to do a job color cannot do — Color and contrast explains why.
Color blindness is mostly already handled
Red-green confusions are the common case, and they matter for exactly one kind of cover: the one where the only thing separating the title from its ground is hue. Red on green, green on brown, orange on olive. To a reader with the common form, those are one tone.
You do not need a separate test for it. A cover that survives grayscale survives color blindness, because both are asking the same question: is there enough difference in lightness? Pass the grayscale check and you have covered it.
In the Cover Maker. Cover check renders the real cover at the sizes stores display it and shows a grayscale panel beside it, so the small view and the desaturated view are one step rather than an export and a trip through an image editor. Start a book → · about the Cover Maker
The listing is read out loud
The cover is one half. The other half is the page it sits on, and some of your readers reach that page through software that speaks it.
Fill in alt text where the store offers the field. Not every retailer does, and which ones do changes — check the store's own help pages rather than assuming. Where it exists, describe what the image shows in a plain sentence. "Cover of The Salt Road, a woman walking a shoreline at dusk" is useful. "Book cover" is not.
Write the description in sentences. A blurb built out of block capitals, star rows, emoji and strings of symbols is read aloud character by character by a screen reader, and the result is unlistenable. It also reads badly to everyone else. Plain paragraphs, ordinary punctuation, headings where you need them — see Check the listing the way a stranger would.
Two things you can actually ship
Beyond the cover, there are two concrete editions that widen who can read the book at all.
A large print edition. Set at 6 × 9 in 16 pt, ragged right, in Luciole — a typeface drawn specifically for low-vision readers. It is a separate edition with its own ISBN and its own listing, and the audience includes libraries. See The large print edition most authors never make.
An accessible EPUB. Accessibility metadata, a declared language, ARIA roles on the structure, and any alt text you wrote for your images carried through into the file. See Accessible ebooks, and why they are now everyone's problem.
This is reach, not compliance
It is tempting to file all of this under obligation and do the minimum. That gets the framing backwards.
A reader who cannot read your cover does not write to tell you. They do not leave a review saying the title was illegible on their phone. They scroll, and you never learn they were there. The cost is invisible, which is exactly why it goes uncorrected for the life of a book.
Three views, one alt text field, and plain sentences in the description. None of it changes your design. All of it changes how many people can see it.
Make yours
Everything here is built into the tools, and they are free to use: name your book, bring your manuscript or your artwork, and work as long as you like. You only pay when you want the files without the preview watermark.
Next: The thumbnail test · More: Color and contrast · The large print edition most authors never make · Accessible ebooks, and why they are now everyone's problem