There is no universal law that alt text must be exactly 125 characters. That number is a practical guideline because many screen reader users prefer brief descriptions, and short alt text is easier to maintain across large websites.
Recommended alt text length
- Target one clear sentence when possible.
- Rough guide: about 125 characters or fewer for most images.
- Prioritize essential information over visual minutiae.
- If the image is complex, keep alt text short and add a longer description on the page.
Good length example (98 characters): Bar chart showing email sign-ups rising from 120 in January to 410 in June.
Too short: chart. Too long: a detailed paragraph repeating every axis label, color, and pixel-level detail when the page already explains the chart below.
Why shorter alt text is usually better
Screen reader users often navigate pages quickly. Long alt text slows them down, especially on pages with many images such as product galleries, blog archives, and social feeds. Concise alt text respects their time while still conveying meaning.
Platform and CMS limits to know
- Some CMS fields truncate alt text silently if you exceed their limit.
- Etsy listing images allow longer alt text, but concise descriptions still work best.
- Social platforms may crop or limit metadata differently than your website CMS.
- API and bulk workflows benefit from consistent short descriptions across channels.
Generate consistent, concise alt text across pages with the Free Alt Text Generator or scale production with paid plans.
When to use a longer description
Maps, scientific diagrams, infographics, and dense data visuals may need more than one sentence. In those cases, use short alt text for the image itself and place the full explanation in visible page content or an aria-describedby target. See our alt text best practices guide for examples by image type.