Image Alt Text for SEO Guide: SEO Guide

What Is Alt Text and Why Does It Matter?

Alt text (alternative text) is an HTML attribute that provides a text description of an image. It appears in place of an image when the image cannot be displayed and is read aloud by screen readers for visually impaired users. In the context of SEO, alt text is one of the primary signals search engines use to understand image content.

<img
  src="seo-audit-dashboard.png"
  alt="Auditite SEO audit dashboard showing Core Web Vitals scores and technical issues"
/>

Alt text serves three critical functions:

Accessibility — screen readers rely on alt text to describe images to visually impaired users. This is not optional — it is a legal requirement under accessibility laws like the ADA and WCAG
SEO — search engines cannot see images the way humans do. Alt text is the primary way Google understands what an image depicts and how it relates to the surrounding content
User experience — when images fail to load (slow connections, blocked resources, email clients), alt text provides context so users understand what they are missing

How Google Uses Alt Text

Google Image Search drives billions of queries every month, and alt text is the single most important ranking factor for image search results. Beyond image search, alt text helps Google understand the content of a page. An image of a graph showing “organic traffic growth” with appropriate alt text reinforces the page’s relevance for traffic-related queries.

Google specifically recommends:

Writing useful, information-rich alt text that uses keywords appropriately
Avoiding keyword stuffing in alt attributes
Keeping alt text concise but descriptive
Not using alt text on purely decorative images

How to Write Effective Alt Text

Be Descriptive and Specific

Good alt text describes what the image actually shows, not what you wish it showed. Be specific enough that someone who cannot see the image understands its content and purpose.

Weak: alt="chart" Better: alt="bar chart comparing page load times across five CDN providers" Best: alt="bar chart showing Cloudflare delivers 45ms average TTFB compared to 120ms for self-hosted servers"

Include Relevant Keywords Naturally

Alt text is a legitimate place to include target keywords — but only when they genuinely describe the image. If the image shows an SEO audit report, including “SEO audit” in the alt text is natural and appropriate. If the image shows a team photo, forcing “SEO audit” into the alt text is keyword stuffing.

Guidelines for keyword inclusion:

Use your target keyword if it accurately describes the image content
Use variations and related terms rather than repeating the exact same keyword on every image
Place the most important descriptive words at the beginning of the alt text
Never sacrifice accuracy for keyword inclusion

Keep It Concise

Screen readers read alt text in a continuous stream. Excessively long alt text becomes difficult to follow. Aim for 125 characters or fewer — this is the point where many screen readers truncate the text.

For complex images like infographics or data visualizations that require more explanation, use a brief alt text and provide a detailed description in the surrounding text or a longdesc attribute.

Context Matters

The same image may warrant different alt text depending on where it appears. A photo of running shoes on a product page should describe the specific product:

alt="Nike Air Zoom Pegasus 41 running shoes in black and white colorway"

The same image used in a blog post about shoe materials might be:

alt="Running shoe with visible Flyknit mesh upper and ZoomX foam midsole"

Match the alt text to the context and purpose of the image on that specific page.

Alt Text Best Practices by Image Type

Product Images

Product images need detailed, specific alt text that helps both accessibility and e-commerce SEO:

Include the product name, brand, and key identifying features
Mention color, size, or variant if the image shows a specific option
Describe what makes this image different from other product images (front view, side view, detail shot)

Example: alt="Leather bifold wallet in cognac brown, showing interior card slots and bill compartment"

Informational Graphics and Charts

Charts, graphs, and diagrams need alt text that conveys the key takeaway — not every data point:

State the type of visualization and its main conclusion
Include the most significant data point if relevant
Provide full data in a table or description elsewhere on the page

Example: alt="Line graph showing 47% increase in organic traffic over 6 months after implementing technical SEO fixes"

Screenshots

Screenshots need enough context for the reader to understand what they are seeing:

Identify the tool or interface shown
Describe what the screenshot demonstrates
Mention key elements or data visible in the screenshot

Example: alt="Google Search Console performance report showing 12,000 impressions and 850 clicks for the past 28 days"

Decorative Images

Purely decorative images — backgrounds, spacers, ornamental borders — should have empty alt attributes:

<img src="decorative-divider.svg" alt="" />

An empty alt="" tells screen readers to skip the image entirely. Do not omit the alt attribute — a missing alt attribute causes screen readers to read the file name, which is worse than no description at all.

Icons

Functional icons (like a search icon or menu icon) need alt text that describes their function, not their appearance:

Correct: alt="Search" or alt="Open navigation menu"
Incorrect: alt="magnifying glass icon" or alt="three horizontal lines"

If the icon is accompanied by visible text that already describes its function, use alt="" to avoid redundancy.

Common Alt Text Mistakes

Keyword Stuffing

Cramming keywords into alt text is the most common abuse:

Bad: alt="SEO audit tool best SEO audit software free SEO audit website audit tool"

This helps neither users nor search engines. Google explicitly warns against keyword-stuffed alt text, and screen readers will subject visually impaired users to a stream of repetitive keywords.

Using “Image of” or “Photo of”

Screen readers already announce that an element is an image before reading the alt text. Starting alt text with “image of” or “photo of” is redundant:

Redundant: alt="Photo of a website dashboard showing SEO metrics" Better: alt="Website dashboard showing SEO metrics including organic traffic and keyword rankings"

The exception is when the medium itself is relevant — for example, alt="Oil painting of a landscape" on an art gallery site.

Identical Alt Text on Multiple Images

Using the same alt text for every image on a page (or across the site) is a missed opportunity. Each image should have unique alt text that describes its specific content.

Ignoring Alt Text Entirely

Many sites have hundreds or thousands of images with no alt text at all. This is an accessibility violation and an SEO miss. Audit your entire site for missing alt text and prioritize fixing images on your most important pages first.

Auditing Alt Text at Scale

For sites with thousands of images, manual alt text review is impractical. Use automated tools to identify:

Images with missing alt attributes — the highest priority fix
Images with empty alt text — verify these are genuinely decorative
Images with excessively long alt text — flag anything over 125 characters for review
Images with keyword-stuffed alt text — detect repetitive keyword patterns
Images with generic alt text — flag common patterns like “image1.jpg” or “untitled”

Auditite’s image optimization audit automatically scans every image on your site and flags alt text issues alongside file size, format, and loading performance problems.

After identifying issues, prioritize fixes by page importance:

Homepage and main landing pages
Top-traffic blog posts and content pages
Product and category pages
All remaining pages

Alt Text and Image Search Rankings

Optimizing alt text is the single most impactful thing you can do for image search visibility. To maximize image search traffic:

Use descriptive file names in addition to alt text — seo-audit-dashboard.png is better than IMG_4521.png
Place images near relevant text content — Google considers surrounding text as additional context
Use structured data where applicable — product images, recipe images, and article images can all be enhanced with schema markup
Optimize image technical factors — file size, format, and lazy loading affect whether images are indexed at all

Key Takeaways

Image alt text is where accessibility and SEO align perfectly. Every image on your site needs thoughtful, descriptive alt text:

Write alt text that accurately describes the image content in context
Include relevant keywords naturally, without stuffing
Keep alt text concise — aim for 125 characters or fewer
Use empty alt attributes for purely decorative images
Audit your entire site for missing and problematic alt text
Match alt text to the image’s purpose on each specific page

Well-optimized alt text improves your site’s accessibility compliance, strengthens your page-level SEO signals, and opens up image search as a traffic channel.