Image Alt Text
Write alt text that helps a person, then helps a search engine.
Alt text is the sentence a screen reader announces in place of an image. It is also what appears when an image fails to load. That makes it one of the few pieces of web copy with two jobs: it has to be useful to a person who cannot see the image, and it has to survive a broken network.
Most alt text fails at the first job. It says “image,” repeats the caption, or stuffs a keyword into every photo. Here is a better way.
The one-sentence rule
Describe the image's content or function in context. That is the whole rule. Everything else is detail.
- If the image shows something, describe what matters.
- If the image does something (a button, a chart, a diagram), describe what it communicates.
- If the image is decorative, use empty alt text so screen readers skip it.
The four questions
Before writing, ask:
- Why is this image here? What would a sighted reader understand from it?
- What is the smallest description that conveys that? Usually one clause.
- Is the information already in the text? If yes, the image may be decorative.
- Does the image contain text? If so, include the text that matters.
12 examples
1. Product photo White ceramic pour-over dripper on a wooden counter beside a bag of coffee beans.
2. Chart Bar chart: mid-market adoption rose from 41% to 59% between 2024 and 2026.
3. Screenshot of a settings page Settings page with “Require two-factor authentication” switched on.
4. Decorative divider alt="" — empty, no description.
5. Logo linked to the homepage AIbyNow home — describe the destination, not the picture.
6. Team photo Six members of the support team standing in front of the office. Only if the identities or the group matter; otherwise empty.
7. Icon next to “Download” alt="" — the adjacent text already says “Download.”
8. Map Map showing the venue at 42 Main Street, two blocks from the Central station.
9. Before-and-after Before: a cluttered desk. After: the same desk with the papers filed and the monitor raised.
10. Screenshot of an error Error dialog: “Your card was declined. Try another payment method.”
11. Infographic Infographic: three steps — upload, convert, download — with a privacy note under step two. The full data belongs in the surrounding text.
12. Portrait used as an author photo Portrait of Priya Shah. If the author's name is already in the byline, empty alt is usually better.
The mistakes that keep showing up
Starting with “Image of” or “Picture of.” Screen readers already announce that it is an image. It wastes the first words.
Repeating the caption. The caption is visible; the alt text should add something or stay empty.
Keyword stuffing. best coffee dripper, buy coffee dripper, ceramic dripper is not a description. It is noise.
Describing every visual detail. “A white cup with a handle on the left, a brown bag on the right, a wooden table with three visible grain lines…” The reader needs the point, not an inventory.
Leaving alt text off functional images. A button that is only an icon needs alt text describing its action: Search, not magnifying glass.
Length
Aim for 5–15 words, and rarely more than 125 characters. Screen readers handle longer descriptions, but most images do not need them. If the image carries a lot of information, put the information in the surrounding text and keep the alt text short.
Alt text and SEO
Alt text can help image search, but it is not a ranking trick. Google's own guidance is to describe the image, not to stuff keywords. The overlap with SEO is simple: a clear, specific description is useful to humans and machines alike.
Write the description first. If a keyword fits naturally, include it. If it does not, leave it out.
A workflow that takes ten seconds
- Look at the image and say out loud what it shows.
- Cut the sentence to the part that matters on this page.
- Remove “image of.”
- Check the length.
- If the image is decorative, use empty alt.
Image Alt Text generates concise, descriptive, and context-rich versions from a line of context. Use it as a drafting aid, then check the result against the questions above. The judgment is still yours — especially for charts, screenshots, and anything with text in it.