Image Alt Text Helper
Build structured, descriptive alternative text for any image.
Describe the image using the fields below. The helper combines them into a single alt text you can copy.
About This Tool
The Image Alt Text Helper guides you through writing effective alternative text (alt text) for images. Alt text is a short textual description embedded in HTML that screen readers read aloud to blind and low-vision users, and that search engines use to understand image content. Well-written alt text is one of the most impactful and straightforward accessibility improvements you can make.
Instead of staring at a blank field, this tool breaks the description into four structured components — subject, action, location, and details — and combines them into a complete, grammatical alt text string. This structured approach ensures your descriptions are consistent, descriptive, and contextually appropriate.
Tool Guide
Describe the subject
What is the main thing in the image? E.g., "A person using a smartphone" — start with the primary subject.
Add the action
What is happening? E.g., "reading the screen with a screen reader" — describe the activity or verb.
Specify the location
Where is this happening? E.g., "at a brightly lit desk" — provide environmental context when relevant.
Include key details
What important visual details would a sighted person notice? E.g., "headphones connected, one hand on the device."
How to Use
- Be concise: Aim for 100–125 characters. Alt text is meant to be brief — include only what's essential to understanding the content's purpose.
- Be accurate: Describe what's actually in the image, not what you wish it conveyed. Don't add interpretation or assumptions.
- Don't start with "Image of": Screen readers already announce "image," so saying "Image of a dog" becomes redundant: "Image. Image of a dog." Just say "A dog."
- Decorative images: If an image is purely decorative (a background swoosh, a spacer), use
alt=""(empty alt text) so screen readers skip it entirely. - Functional images: If an image is a button or link (e.g., a magnifying glass for search), describe the action, not the visual: "Search" not "Magnifying glass icon."
- Complex images: Charts, infographics, and diagrams often need longer descriptions. Consider providing both brief alt text and a separate detailed text description in the surrounding content.
Frequently Asked Questions
What is alt text and why does it matter?
Alt text (alternative text) is a short description of an image embedded in HTML code (alt="description"). It allows screen readers to describe images to blind users, helps search engines index images for SEO, and displays when images fail to load. It's a fundamental pillar of web accessibility.
How long should alt text be?
Aim for 100–125 characters (roughly one sentence). The key is to convey the image's purpose and essential content without overwhelming the listener. For complex images like charts, provide brief alt text plus a longer text description elsewhere on the page.
Should every image have alt text?
Not necessarily. Decorative images that add no informational value should use alt="" (empty alt attribute), which tells screen readers to skip them. Functional images (buttons, icons) should have alt text describing the action. Informative images need descriptive alt text.
Can I use this tool for complex charts and infographics?
This tool generates concise alt text suitable for most images. For complex data visualizations, use this tool for a brief summary, then provide a full text alternative (like a data table or detailed description) in the page content. WCAG requires both for complex images.
What's the difference between alt text and a caption?
Alt text describes the image for screen reader users and is not visible on screen. A caption is visible text that provides context, attribution, or commentary about the image. An image can have both — alt text for accessibility and a caption for all viewers.
Does good alt text help with SEO?
Yes. Search engines cannot "see" images — they rely on alt text to understand and index image content. Well-written, descriptive alt text improves image search rankings and helps your content appear in relevant image search results.