Alt Text Best Practices Guide

Learn how to write effective alt text that improves accessibility and SEO. Want to improve your content writing? Check out ReachWriter for AI-powered content creation.

What Makes Good Alt Text?

Good alt text serves two purposes: it helps screen reader users understand your images, and it provides context for search engines. The best alt text is:

Descriptive: Clearly describes what's in the image
Concise: Typically under 125 characters (screen reader limit)
Contextual: Relevant to the page content and purpose
Meaningful: Adds value for users who can't see the image
Natural: Sounds like normal human language, not keyword stuffing

Do's and Don'ts

Do's

✓Be specific and descriptive
✓Include relevant details (colors, people, actions)
✓Match the image's purpose on the page
✓Keep it under 125 characters when possible
✓Use decorative images with empty alt (alt="")
✓Include text visible in the image if important

Don'ts

✗Start with "image of" or "picture of"
✗Stuff keywords for SEO
✗Leave alt text empty on meaningful images
✗Use file names (IMG_1234.jpg)
✗Write novels (keep it concise)
✗Repeat surrounding text content

Examples

[IMG]

Bad

alt="business meeting"

Good

alt="Five diverse professionals collaborating around a conference table reviewing marketing charts"

[IMG]

Bad

alt="product.jpg"

Good

alt="Blue wireless headphones with noise cancellation and folding design"

[IMG]

Decorative Image (border, icon, etc.):

Correct

alt=""

Empty alt tells screen readers to skip decorative images

[IMG]

E-commerce Product:

Bad

alt="running shoes"

Good

alt="Nike Air Zoom Pegasus 40 men's running shoes in black and white"

[IMG]

Blog Post Photo:

Bad

alt="recipe image"

Good

alt="Freshly baked chocolate chip cookies on cooling rack with melted chocolate chips visible"

[IMG]

Social Media Post:

Bad

alt="sunset photo"

Good

alt="Orange and pink sunset over mountain peaks with silhouetted pine trees in foreground"

[IMG]

Documentation Screenshot:

Bad

alt="screenshot"

Good

alt="Settings menu showing Enable Notifications toggle switch in the on position"

[IMG]

Infographic with Data:

Bad

alt="statistics"

Good

alt="Bar chart showing website traffic increased 45% in Q4 2024 from 10K to 14.5K monthly visitors"

WCAG 2.1 Accessibility Guidelines

The Web Content Accessibility Guidelines (WCAG) provide standards for accessible web content. For images:

Level A (Required): All non-decorative images must have alt text
Decorative Images: Use empty alt (alt="") to indicate the image is purely decorative
Complex Images: Provide longer descriptions using aria-describedby or longdesc when needed
Text in Images: Avoid using images of text; if unavoidable, include the text in alt attribute
Functional Images: Describe the function/action, not the image itself (e.g., "Search" not "Magnifying glass icon")

Learn more: WCAG 2.1 Text Alternatives Guidelines

Alt Text for SEO

Alt text helps search engines understand your images and can improve your SEO:

Include Target Keywords Naturally: Use relevant keywords, but don't force them
Be Descriptive: Detailed descriptions help Google Images index your content
Context Matters: Match alt text to the page topic and surrounding content
Avoid Keyword Stuffing: Google penalizes unnatural keyword repetition
File Names Also Matter: Use descriptive file names like "blue-wireless-headphones.jpg"

Balance is Key: Good alt text serves both accessibility AND SEO. Prioritize users first, search engines second.

Common Mistakes to Avoid

1. Keyword Stuffing

Bad: "Buy blue headphones best headphones wireless headphones sale discount"

Good: "Blue wireless headphones with noise cancellation"

2. Being Too Vague

Bad: "A person"

Good: "Woman smiling while working on laptop at coffee shop"

3. Repeating Context

Bad: Adding "Image of a blue car" when the caption already says "Our new blue car model"

Good: Add unique details like "Sleek sedan with chrome accents parked in showroom"

4. Using "Image of" or "Picture of"

Bad: "Image of a sunset over the ocean"

Good: "Sunset over calm ocean with orange and purple sky"

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