SEOBestie*
SEO · Search Engine Optimisationbeginner3 min read

What is Alt Text?

Alt text (alternative text) is an HTML attribute added to image tags that describes the content of an image. It serves two purposes: accessibility (screen readers read alt text to visually impaired users) and SEO (it tells search engines what an image depicts, since they can't truly 'see' images). Good alt text improves image search rankings, contributes to page relevance, and is required for accessibility compliance.

Fact-checked against 3 sourcesLast updated 8 June 2026
Key Takeaways
  • Alt text should describe what's in the image specifically and concisely — not stuff keywords.
  • Decorative images (dividers, background patterns) should have empty alt text (alt='') so screen readers skip them.
  • In Next.js, the next/image component requires an alt prop — making good alt text a mandatory practice.
  • Images without alt text are invisible to Google Image Search — a meaningful source of traffic for visual content.
  • Alt text is one of the fastest accessibility and SEO wins: audit missing alt text with any crawler and fix in bulk.
In this article
  1. 01Writing Good Alt Text
  2. 02Alt Text and SEO

Writing Good Alt Text

Describe what you actually see: 'Bar chart showing organic traffic growth from 1,000 to 15,000 monthly visitors between January and December 2024' is good alt text. 'Graph' is not. 'SEO traffic growth chart keyword keyword' is keyword stuffing.

Be specific about context: 'Person using Google Search Console on a laptop' is more useful than 'person on laptop'. The alt text should convey what a sighted user would take from the image.

For product images: include the product name, key attributes, and colour. 'Nike Air Max 90 running shoe in white and black, side profile view' is complete.

Keep it under 125 characters when possible — screen readers typically truncate at that length.

Alt Text and SEO

Google uses alt text as a primary signal for understanding image content. Pages with descriptive alt text on relevant images rank better in image search and the images can appear in Google Discover and visual carousels.

Alt text also contributes to overall page relevance — an article about Core Web Vitals with an image alt-texted 'screenshot of PageSpeed Insights score' reinforces the page's topical relevance.

For programmatic SEO sites: if you're auto-generating pages, ensure alt text is also generated dynamically based on image content, not left as a generic placeholder or left empty.

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✓ DO
✓

Describe the image content specifically: 'Red bar chart showing 40% conversion rate increase after site redesign'

✓

Include product name, colour, and angle for e-commerce images: 'Adidas Stan Smith trainers in white and green, front-facing view'

✓

Use your target keyword naturally when it genuinely describes the image

✓

Write alt text for decorative infographics as if describing it to someone over the phone

✓

Keep alt text under 125 characters to avoid screen reader truncation

✗ DON'T
✗

Stuff keywords: 'SEO tips SEO guide SEO checklist SEO 2024 best SEO'

✗

Use filename as alt text: 'IMG_4872.jpg' or 'screenshot-final-v3.png'

✗

Write 'image of' or 'picture of' — screen readers already announce it as an image

✗

Leave alt text empty on informational images (reserve empty alt only for purely decorative elements)

✗

Use the same alt text for different images on the same page

22.6%
of Google search results include an image pack or image carousel
~1%
of images on the web have descriptive, meaningful alt text
7.6M
visually impaired internet users in the US relying on screen readers
125
characters — typical screen reader truncation limit for alt text
WEAK VS. STRONG ALT TEXT EXAMPLES
Weak Alt TextStrong Alt Text
graphBar chart showing organic traffic growth from 1,000 to 15,000 monthly visitors, Jan–Dec 2024
shoesNike Air Max 90 running shoe in white and black, side profile view
screenshotScreenshot of PageSpeed Insights showing a Core Web Vitals score of 94 on mobile
team photoFive-person marketing team collaborating around a whiteboard in an open-plan office
logoAcme Corp logo — blue circle with white letter A and company name in sans-serif font
ALT TEXT AUDIT CHECKLIST
0/8 complete
Every non-decorative image on the page has a non-empty alt attribute
Alt text describes what is visually shown, not just the image topic
No alt text contains keyword repetition or unnatural phrasing
Product images include name, colour, and view angle
Charts and graphs describe the data trend or key takeaway, not just the chart type
Purely decorative images use an empty alt attribute (alt="") so screen readers skip them
Programmatically generated pages auto-generate contextual alt text, not generic placeholders
No alt text begins with 'image of', 'photo of', or 'picture of'
⚠️
Empty Alt Text ≠ Missing Alt Text

There is a critical difference between alt="" (empty, intentional — tells screen readers the image is decorative and to skip it) and a missing alt attribute entirely (causes screen readers to read out the file name, creating a poor experience). Always include the alt attribute on every image tag; use empty string only for images that add no informational value.

REAL-WORLD EXAMPLE
How John Lewis Structures Alt Text for E-Commerce SEO

Large e-commerce retailers like John Lewis dynamically generate alt text at scale using a template: '[Brand] [Product Name] [Product Type] in [Colour/Variant], [View Angle or Key Feature]'. For example: 'KitchenAid Artisan Stand Mixer in Almond Cream, front view with mixing bowl attached'. This approach serves three goals simultaneously: it gives Google's image search enough signal to rank product images, it provides screen reader users a complete mental picture of the product, and it naturally incorporates long-tail commercial keywords without stuffing. The template is applied programmatically via the product catalogue attributes, meaning thousands of SKUs have accurate alt text without manual copywriting.

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Frequently Asked Questions

It contributes to image search rankings and reinforces page relevance, but it's not a primary organic ranking factor. The bigger SEO impact of alt text is accessibility compliance (which affects E-E-A-T signals) and image search traffic. The biggest impact is simply not having a common technical issue flagged in audits.

SVG images inline in HTML can have a title element for accessibility. CSS background images have no alt text equivalent — any image that conveys meaningful information should be an HTML img element, not a CSS background. Pure decorative images are fine as CSS backgrounds.

Sources & Further Reading
  • 1.Google — Image SEO best practices
  • 2.WebAIM — Alternative Text guide
  • 3.Next.js — Image component documentation

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