Why are my images missing alt text and does it matter?
It matters for people using screen readers, for image search, and for anything trying to understand your page. The fix is small and the excuses are usually wrong.
Yes it matters, primarily because screen reader users get nothing at all from an unlabelled image. It also costs you image search traffic and weakens how well any machine understands the page. Every content image needs an alt; decorative images need alt="", which is not the same as leaving it off.
The three reasons
- Accessibility. A screen reader encountering
<img src="chart-2024-final.png">with no alt reads the filename aloud, or announces "image" and moves on. Either way the information is lost. This is a WCAG 1.1.1 failure and, in many jurisdictions, a legal exposure. - Image search. Alt text is the main thing search engines use to understand what an image depicts.
- Comprehension. Anything reading your page — crawlers, assistants, link preview generators — uses alt text to understand what the images contribute.
Writing alt text that works
| Image | Bad | Good |
|---|---|---|
| Product photo | alt="product" | alt="Blue ceramic mug, 350ml, with a curved handle" |
| Chart | alt="chart" | alt="Revenue by quarter 2024, rising from £1.2m in Q1 to £2.8m in Q4" |
| Decorative divider | alt="divider" | alt="" |
| Logo linking home | alt="logo" | alt="Example Ltd — home" |
| Photo of a person | alt="image of a person" | alt="Dr Jane Doe presenting at the 2026 conference" |
Rules that hold up: describe the function and the information, not the appearance; skip "image of" and "picture of", which screen readers already announce; keep it under about 125 characters, and put longer explanations in the surrounding text where everyone benefits.
The empty alt is a decision, not an omission
For an image carrying no information — a decorative flourish, a spacer, a background texture — write alt="". That tells assistive technology to skip it entirely, which is exactly right.
Omitting the attribute is different: the screen reader does not know whether the image matters, so it frequently falls back to reading the filename. alt="" is silence. No alt attribute is noise.
Why it goes missing
- A CMS where the alt field is optional and nobody fills it. Make it required.
- Images inserted by editors through a visual builder that hides the field.
- Programmatic galleries that render
<img>from a data source with no alt column. - The genuinely awkward one: the filename gets used as alt automatically, producing
alt="IMG_4471.jpg", which is worse than nothing because it looks filled in.
Fixing a backlog
- Crawl the site and list every image with its alt, so you know the real number.
- Fix images on your highest-traffic pages first.
- Set
alt=""on everything genuinely decorative — often a third of the list, disposed of quickly. - Make the field required in the CMS so the backlog stops growing.
- Add a check to your build or review process.
What our audit reports about this
Every item below is measured directly, not inferred. Run it against your own site and the result names the exact rule or header responsible.
- Every image on the page with its alt text, and a count of those with none.
- Alt text that is a filename, or that begins with "image of" and similar filler.
- Whether decorative images correctly use an empty alt.
- Whether images declare width and height, which affects layout stability.
For agents and scripts, the same measurement is at
/api/v1/a11y?url=yoursite.com —
see the API documentation.
Related questions
Does alt text help SEO?
For image search, directly. For page ranking, marginally — it contributes to understanding the page. The accessibility argument is much stronger and should be the reason you do it.
What about images loaded by CSS?
A CSS background image is invisible to assistive technology by design, which is correct for decoration. If an image carries information, it belongs in an <img> with alt text, not in a stylesheet.
How long should alt text be?
Usually under 125 characters. If the image needs more explanation — a complex diagram or data chart — put the full description in the page text and keep the alt as a short summary. Everyone benefits from that, not just screen reader users.
Read next
Why do my images need alt text?
Because without it, some people get nothing at all — and everything else that reads your page gets nothing either.
ReadIs my website accessible? How do I check?
What automated testing can and cannot tell you, the three manual tests worth more than any tool, and where to start on a real backlog.
ReadHow can I improve my SEO?
The work that actually moves rankings, ordered by effect per hour spent — and the popular tasks that do almost nothing.
ReadWhat is a skip link and do I need one?
A hidden link that lets keyboard users jump past your navigation. Five lines of code, and without it every page starts with the same twenty tab presses.
Read