TL;DR: Alt text helps Google understand what an image shows, so it matters for image search. Google’s documentation does not call it a ranking factor for normal web search, so don’t expect it to lift a page’s rankings on its own. The stronger reason to write it well is accessibility: it is how people using screen readers get the content of your images. Describe each image briefly and accurately in the context of the page, leave the alt text empty for purely decorative images, and don’t stuff it with keywords.
Alt text (alternative text) is a short description added to an image in the page’s HTML. Screen readers read it aloud and search engines use it to understand what the image is about.
Does Alt Text Help SEO?
Yes, mainly for image search. Google’s image SEO guidance says alt text is the most important attribute for giving it more information about an image, and that it uses alt text together with computer vision and the content of the page to understand what an image shows. If an image is a link, Google also says its alt text is useful as anchor text for that link. To see how Google finds and reads images in the first place, see our guide to what Google sees when it crawls your site.
What Google doesn’t say is how much weight alt text carries, or that it is a ranking factor for normal web search. Anything beyond image search, such as alt text lifting a page’s ordinary rankings, is unconfirmed. For most businesses, we would treat it as a small extra on top of the page’s own text, not a lever.
How much it matters depends on how much of your traffic comes from image search. The search type filter in Search Console’s Performance report lets you look at image searches on their own.
Why Alt Text Matters Beyond SEO
Google’s own guidance says alt text improves accessibility for people who can’t see images, including people who use screen readers or have low-bandwidth connections. The W3C says images need text alternatives that describe the information or function they carry, and the Web Content Accessibility Guidelines include this as success criterion 1.1.1, a Level A criterion that asks for a text alternative serving the same purpose as the image.
There can be a legal side too. The European Accessibility Act, Directive (EU) 2019/882, is EU law, applied through the national laws of EU member states. It applies to a defined list of services provided to consumers after 28 June 2025, which includes e-commerce services. Microenterprises providing services are exempt, and the Directive defines these as fewer than 10 staff with turnover or balance sheet of no more than EUR 2 million. The Directive’s text doesn’t use the term alt text, and whether it applies to your business, including if you only trade in the UK, is a question for a legal adviser, not an SEO.
How to Write Good Alt Text
Describe what the image shows and why it is on this page, in a short phrase. Google’s SEO starter guide calls alt text short but descriptive, and the best example in its image guidance is four words: “Dalmatian puppy playing fetch”. The right answer depends on the job the image does, so start with the image, not the keyword.
| Type of image | What to do | Example wording (illustrative) |
|---|---|---|
| Photo or graphic that adds information | Write a short, specific description that fits the page. Use a keyword only where it genuinely describes the image. | Red trail running shoe with deep tread |
| Keyword-filled description | Avoid it. Google warns that stuffing keywords into alt attributes gives a poor experience and may cause your site to be seen as spam. | Not: running shoes cheap running shoes buy trail shoes online |
| Purely decorative image | Leave the alt attribute empty (alt=””). The W3C says to use an empty alt for images that are only decoration or not meant for users. | A divider line or background flourish |
| Image of text, such as a banner | If the same words appear as real text nearby, leave the alt empty. If the text appears nowhere else, put it in the alt text. | Spring sale: 20% off all trainers |
| Chart or diagram | Say briefly what it shows, and put the full information in the page text, not only in the alt attribute. | Line chart showing monthly enquiries rising through the year |
| Image used as a link | Describe where the link goes or what it does. Google says alt text is useful as anchor text here. | Download the 2026 pricing guide |
We would also leave out “image of” and “picture of” at the start. They add length without telling the reader anything. For image topics beyond alt text, such as file names, sitemaps and page speed, see our wider guide to how important images are for SEO.
Common Alt Text Mistakes
- Leaving it out. Google’s own guidance lists an image with no alt text as a bad example. Check informative images first.
- Using the file name or the same text everywhere. Alt text such as IMG_2034 or the page title repeated on every image tells nobody anything.
- Trusting auto-generated text without checking it. A generic description such as “photo of a beach” won’t reflect why the image is on that page. Read what your tool has produced.
“The mistake I see most when reviewing client sites is the same alt text repeated across every image on a page. A screen reader user can’t tell those images apart, and search engines get no signal about what each one shows. It’s one of the quickest fixes there is, so it’s the first thing I check.”
Eviee Taylor, SEO Senior Executive
Top Tip: Pick your five most important pages and read the alt text on each image without looking at the image. If you can’t tell what the image shows or why it is on that page, rewrite it. If you can’t think of anything useful to say, the image may be decorative and should have an empty alt attribute.
“On one client’s services pages, most of the images had alt text written to hit the keyword they wanted to rank for, not to describe the picture. Most of the time it didn’t match what the image showed, and when I hovered over images on the live page, the description that came up was long. I can’t say I’ve seen a change in the search results, but the pages feel less bloated when you hover over the images. For me, that’s the real test of alt text: does it help the person looking at the page, not just the crawler? Fixing it is a quick job, and it’s worth doing for the user even if the rankings never move.”
Lucy Young, SEO Senior Executive
Alt Text FAQs
How long should alt text be?
Google’s image SEO guidance gives no length limit. Its SEO starter guide calls alt text short but descriptive, and for most images a short phrase is enough. For a complex chart, keep the alt text brief and put the detail in the page itself.
Should every image have alt text?
Every image should have an alt attribute, but not every image needs a description. Informative images need a short description. Purely decorative ones should have an empty alt attribute, which is the W3C’s recommended way to mark an image as decorative. Leaving the attribute out altogether is different, and is what Google lists as a bad example.
How do I check what alt text my images have?
For one image, right-click it, choose Inspect and look for the alt attribute on the img tag. For a whole site, a common approach is a site crawl that lists images with a missing alt attribute. An empty alt attribute is not an error if the image is decorative.
How Wildcat Handles Alt Text and Image SEO
Alt text is one of the smaller jobs within technical SEO, so it rarely needs a project of its own. Our technical SEO page explains that an audit early in a campaign gauges the health of your website and sets priorities for the first few months, and it lists compressing images and lazy-loading among the ways we can help with site speed.
If you’d like a second opinion on how your images are handled, get in touch with our team. You can book a free 30-minute consultation with our growth team, tell us which pages matter most, and we’ll give you an honest view of where we think the biggest opportunities are.
Kezia Humphries
SEO Executive
