Writing Alt Text That Actually Works

Alt text is the first accessibility requirement anyone learns and the one most consistently done badly. Automated checkers report whether alt text exists, so organizations fill every field, pass the scan, and leave screen reader users no better off than before.

The rule is not “describe the image.” It is “convey what the image is there to convey.” Those produce different text, and the difference is everything.

Start by asking why the image is there

The same photograph needs different alt text depending on its job on the page.

A photo of a person signing a document:

• Illustrating an article about notarization — alt="A notary applying a seal to a document"
• A staff headshot on a directory page — alt="Maria Chen, Language Access Coordinator"
• Purely decorative, next to text that already says everything — alt=""

Same file. Three correct answers. There is no such thing as the right alt text for an image in isolation — only the right alt text for an image in a context.

Decorative images should be empty, not undefined

If an image adds nothing beyond what surrounding text already provides — a divider, a background flourish, an icon next to a label that already says “Download” — give it alt="".

An empty alt attribute tells a screen reader to skip the image silently. That is correct and helpful.

A missing alt attribute is different: many screen readers fall back to announcing the filename, so users hear “hero-banner-final-v3-compressed dot jpg.” Empty and missing are not the same thing, and only one of them is right.

Length and content

Aim for one clear sentence. If you genuinely need more than about two, the image is probably carrying information that belongs in the page text where everyone can read it.

• Do not start with “Image of” or “Photo of.” Screen readers already announce that it is an image. You are making users listen to the same word every time.
• Do not stuff keywords. It degrades the experience for the people the attribute exists to serve, and search engines are not fooled by it.
• Do not duplicate the adjacent caption. Users hear it twice. If a caption already conveys it, the image can often be alt="".
• Include text that appears in the image. If a graphic contains words, those words must reach the user somehow.

Charts and data visualizations

The most common failure in institutional content: alt="Chart showing quarterly data." That tells a user there is a chart and nothing else.

Alt text for a chart should convey the finding, not the format. The chart exists to make a point — put the point in the alt text.

• Weak: alt="Bar chart of language requests"
• Better: alt="Bar chart: Spanish requests grew from 12% to 34% of total volume between 2023 and 2026, while all other languages stayed flat"

If the underlying numbers matter and not just the trend, the chart needs more than alt text: put the data in an accessible table near it, or link to one. A complex chart is not an alt-text problem — it is a page-content problem.

Logos, icons, and buttons

• A logo that links somewhere — describe the destination: alt="Taika Translations home". Not alt="logo".
• An icon that is the only content of a button — the alt text is the action: alt="Search", not alt="magnifying glass". Users need what it does, not what it looks like.
• An icon beside a text label — decorative. alt="", because the label already speaks.

The test: would a sighted user reading only your alt text be able to operate the page?

Scanned documents and images of text

An image of a page of text is invisible to a screen reader. This is common in agency PDFs — a scanned form, a signed memo, a letter photographed and inserted.

Alt text cannot rescue these. A paragraph of content does not belong in an alt attribute. The fix is to make the text real:

• Run OCR and correct it, so the words become selectable text.
• Or provide the same content in an accessible format alongside it.

Scanned documents are also where accessibility and translation work overlap, since a scan cannot be translated until it is text either. See our PDF remediation guide.

Where alt text lives outside the web

It is not a web-only attribute:

• Word and PowerPoint — right-click, Edit Alt Text. This carries into the exported PDF if you export correctly. See making Office files accessible.
• PDFs — figures need alt text in the tag tree; remediation tools set it.
• Email — images blocked by default make alt text the only content many recipients see.
• Social media — every major platform now supports it.

A quick self-check

Before publishing, for each image ask:

1. Why is this here? No answer means it is decorative — alt="".
2. What would someone miss if it did not load?
3. Does my alt text convey that, in a sentence?
4. Does it contain any text shown in the image?
5. Am I repeating a nearby caption?

Then test it properly: turn images off in your browser, or run a screen reader over the page. A page that still makes sense with every image replaced by its alt text has good alt text. That is a better check than any scanner, and it takes a few minutes.

More on where automated tools stop being useful: how to run a website accessibility audit.

Getting help

Taika provides PDF & document accessibility, Section 508 remediation, accessibility assessments, and ADA website accessibility.

If you have a document library where the images, scans, and charts need to become genuinely accessible, request an assessment.