How To Write Alt Text That Earns Its Place

Alt text has been mangled by being taught as an SEO task. Written as a keyword slot it fails its actual users, and it does not help rankings either, so it is the rare case where the ethical answer and the effective answer are identical.

The correct mental model: a person is using a screen reader, or an image failed to load, and your alt text is the only version of that image they get. Write for them and everything else follows.

The Decision Comes Before The Wording

Most alt text problems are decisions made wrong rather than sentences written badly. The W3C’s alt decision tree is the canonical version, and it comes down to four cases.

Decorative. The image adds nothing the text does not already say. Correct answer is alt="", an empty attribute, which tells assistive technology to skip it. Not a missing attribute, which makes some screen readers announce the filename.

Informative. The image carries information not in the surrounding text. Describe that information.

Functional. The image is a link or a button. Describe what it does, not what it looks like. The alt text for a magnifying glass icon is “Search”, not “magnifying glass”.

Text in an image. Repeat the text exactly. Then consider whether it should be an image at all.

Getting the first case right removes most of the work. A stock photo above an article is decorative, and the correct alt text is nothing.

Describe The Point, Not The Pixels

The most common informative-image failure is describing what is visible rather than what the image is doing in the argument.

Before:

alt=“A screenshot of a computer screen showing a software application with various interface elements and a text box”

After:

alt=“The Wrivio overlay showing the original message on top and the rewritten version below, with the engine toggle set to Local”

The second version conveys what the reader would take from the image. The first conveys that an image exists, which they already knew.

For charts, give the finding rather than the shape: “Bar chart showing local model throughput falling from 18 to 4 tokens per second on pre-2016 hardware” beats “a bar chart with several bars”.

Length And The Keyword Mistake

Aim for roughly one sentence, under about 125 characters where possible. Longer descriptions belong in a caption or in the body text, where every reader gets them rather than only screen reader users.

Do not stuff keywords. It makes the text unusable for the people who depend on it, it is explicitly discouraged as a practice, and the ranking benefit people are chasing was never large. An image search result comes from the surrounding page as much as from the attribute.

Do not begin with “image of” or “picture of”. Screen readers already announce that an image is present, so those three words are pure noise repeated on every image on the page.

Where This Is Now Load Bearing

Two things changed the stakes.

Accessibility requirements have tightened in several jurisdictions, and public sector and enterprise procurement increasingly asks for a conformance statement. Alt text is the most visible and most commonly failed item in an audit.

Separately, assistants describing your page to a user work from the text layer. An image with no description is invisible to that process, so a page whose key evidence is a chart with empty alt text has hidden its evidence, which is the same failure mode described in how to audit a page for AI citability.

A Context For A Batch Pass

Alt text is best fixed in batches, because the decision is easier to apply consistently when you see twenty at once.

A Wrivio Context for this could say:

Rewrite each of these image descriptions into one sentence stating what information the image conveys. Remove openers such as image of and picture of, and remove keyword lists. Keep every product name, figure, and interface label exactly as written. Do not describe elements, data, or labels that are not mentioned in the original.

Press Ctrl+Shift+Space, paste the list, and check the diff. The final clause is the important one, because a rewrite asked to make a description vivid will invent plausible interface details, and alt text describing a button that does not exist is worse than no alt text at all.

The Quickest Audit

Turn images off in your browser, or read the page with a screen reader for two minutes. Any place where the page becomes incoherent is a decoration decision made wrong or an informative image left undescribed.

That takes five minutes per template and finds more than a scanner will, because the scanner can tell you an attribute is missing but not that the one you wrote is useless. The same principle applies to the rest of a house standard, which is worth writing down once in a content style guide.

Common Questions

Does alt text help SEO?

Marginally, for image search, and mainly by being accurate. Keyword stuffing does not help and makes the attribute useless for the people who rely on it.

What should decorative images have?

An empty alt attribute, written as alt="". Omitting the attribute entirely is different and can cause some screen readers to read out the filename.

How long should alt text be?

Around one sentence, ideally under 125 characters. If the image needs more explanation than that, put the explanation in the page text where everyone can read it.

What about images of text?

Repeat the text exactly in the alt attribute, and reconsider whether it should be an image, since text in an image cannot be selected, translated, or resized.

Download Wrivio for Windows to rewrite a batch of image descriptions consistently, without a rewrite inventing interface details you never captured.