Alt text no more than 100 characters

Definition The text alternative for an image must be no more than 100 characters in length.
Purpose
  • A text alternative should summarize the purpose of an image as succinctly as possible for people with visual impairments.
  • Overly long text alternatives can reduce usability by increasing the time it takes to read a web page and understand the significance of the included images.
  • An image with a text alternative that is an empty string (e.g. alt="") is ignored by assistive technologies, and indicates that it is being used for purely decorative, spacing or stylistic purposes rather than for meaningful content.
Required No for HTML4 Legacy Techniques ruleset mapping
WCAG 2.0 Success Criteria

1.1.1 Non-text Content (Level A, Primary Success Criterion)

Rule Category Images
Scope Element
Target Resources img, area and [role="img"] elements
  • area
  • img
Techniques
  • A text alternative (e.g. in English and many other Western languages) should describe the purpose of an image as succinctly as possible (preferably with no more than 100 characters).
  • If a text alternative requires more than 100 characters, consider using the aria-describedby, title or longdesc attribute for a longer, more detailed description of the image, along with shortening the text alternative content.
Informational Links