Image Alt Text for SEO: How to Write Alt Tags That Actually Help You Rank

What Alt Text Actually Does

Alt text (short for "alternative text") is the text description you attach to an image in HTML. It serves two purposes: screen readers use it to describe images to visually impaired users, and search engines use it to understand what an image shows.

Here's what it looks like in code:

<img src="warehouse-layout.jpg" alt="Overhead view of warehouse with labeled picking zones and shipping dock" />

Google can't "see" your images the way humans can. Alt text is how you tell Google what's in the picture. Without it, your images are invisible to search engines — and you're leaving image search traffic on the table.

Why Most Alt Text Is Terrible

The most common alt text patterns are also the worst:

• Empty alt text: alt="" — tells search engines nothing
• Filename stuffing: alt="IMG_4392.jpg" — useless to everyone
• Keyword spam: alt="best plumber plumbing services cheap plumber near me" — Google sees through this
• Overly generic: alt="image" or alt="photo" — why bother?

Google's John Mueller has said directly that keyword-stuffed alt text can be seen as spam. It won't help your rankings, and it might hurt them.

How to Write Good Alt Text (5 Rules)

1. Describe What You Actually See

Be specific. Don't say "a dog" when you can say "golden retriever puppy sitting on a red couch." The more specific your description, the more search queries it can match.

Bad: alt="team photo" Good: alt="Five-person marketing team standing in front of whiteboard with Q2 campaign timeline"

2. Keep It Under 125 Characters

Screen readers typically cut off alt text around 125 characters. If your description needs to be longer, you're probably over-explaining. Aim for one clear sentence.

3. Include Your Target Keyword — Once, Naturally

If the image genuinely relates to your target keyword, include it. The key word is "genuinely." An image of your product page should mention the product name. A decorative stock photo of a sunset doesn't need your keyword forced into it.

Natural: alt="SEO Toolkit dashboard showing keyword density analysis results" Forced: alt="best free SEO tools keyword density checker online free 2026"

4. Skip "Image of" and "Photo of"

Screen readers already announce that something is an image. Starting with "image of" or "photo of" wastes your 125 characters on redundant information.

Redundant: alt="Photo of a broken link error page" Better: alt="404 error page showing broken chain link icon"

5. Use Empty Alt for Decorative Images

Not every image needs alt text. Decorative elements — background patterns, spacer images, purely aesthetic icons — should use alt="" (empty alt). This tells screen readers to skip them entirely, which is the right behavior.

<!-- Decorative: skip it -->
<img src="divider-line.svg" alt="" />

<!-- Meaningful: describe it -->
<img src="quarterly-revenue-chart.png" alt="Bar chart showing Q1-Q4 revenue growth from $50K to $210K" />

Alt Text for Different Image Types

Different images need different approaches:

Product Images

Include the product name, color, size, or distinguishing features. Think about what a customer would search for.

alt="Nike Air Max 90 in white and university red, men's size 10"

Charts and Graphs

Describe the data trend, not just "a chart." The alt text should convey the insight the image communicates.

alt="Line graph showing organic traffic increasing 340% from January to June 2026"

Screenshots

Describe what the screenshot shows and why it matters in context.

alt="Google Search Console coverage report showing 12 pages with 'Crawled - currently not indexed' status"

Infographics

For complex infographics, keep alt text brief and use a text-based version elsewhere on the page for the full content.

alt="Infographic summarizing 7 on-page SEO factors — full text version below"

How Alt Text Impacts Image Search Traffic

Google Image Search drives more traffic than most people realize. According to Sparktoro's research, Google Images accounts for over 20% of all web searches. If your images have good alt text, they can show up in:

• Google Image Search results
• Google Lens visual searches
• Image packs in regular search results (those image thumbnails at the top of some SERPs)

Pages with properly optimized images see measurable lifts in total organic traffic. You won't get a #1 ranking from alt text alone, but combined with quality content and proper meta tags, it compounds.

Common Alt Text Mistakes That Hurt Rankings

Duplicate alt text across multiple images. If every product image on your page says alt="running shoes", Google can't differentiate them. Make each one unique.

Missing alt text on key images. Run your site through a heading and structure checker or use browser dev tools to find images without alt attributes. Missing alt text is one of the most common accessibility audit failures.

Alt text that doesn't match the page content. If your page is about email marketing but your image alt text mentions social media, that sends mixed signals. Keep everything aligned with the page's topic and target keywords.

Not updating alt text when you change images. Swapped out an old screenshot for a new one? Update the alt text too. Stale alt text that describes something no longer visible is confusing for screen readers and unhelpful for SEO.

Tools That Make Alt Text Easier

Writing alt text for dozens or hundreds of images gets tedious. A few approaches to speed it up:

AI-powered generation: Our AI Alt Text Generator analyzes your images and produces descriptive, SEO-friendly alt text automatically. It's especially useful for large batches — upload your images and get alt text suggestions you can review and tweak.

Bulk auditing: Use your browser's accessibility inspector (Chrome DevTools → Lighthouse → Accessibility) to find every image missing alt text. Fix the worst offenders first — hero images, product photos, and images near your H1.

CMS plugins: WordPress has several plugins (like Flavor's Alt Text AI) that can auto-generate alt text on upload. Useful if you're publishing frequently and don't want to slow down.

For deeper on-page analysis beyond images, tools like Semrush's Site Audit can flag alt text issues alongside other SEO problems in a single crawl.

Alt Text Checklist

Before you publish any page, run through this:

• Every meaningful image has descriptive alt text
• Decorative images use alt=""
• No alt text exceeds 125 characters
• Target keyword appears naturally in at least one image's alt text
• No duplicate alt text across images on the same page
• Alt text accurately describes what the image shows
• Product images include identifying details (name, color, model)
• Charts and graphs describe the data insight, not just "a chart"

Quick Wins

If you're starting from zero, prioritize these pages first:

1. Homepage — your most-visited page, often has the most images
2. Product/service pages — directly tied to revenue keywords
3. Blog posts with custom graphics — these have the best chance of ranking in image search
4. Landing pages — every element should support conversions, including image descriptions

Pair your alt text improvements with solid meta tags and proper structured data for the best compound effect on your organic visibility.