Social Media Alt Text Guide 2026: Write Descriptions That Work
Quick answer: Good alt text communicates the information a sighted viewer gets from the image. Lead with the subject and action, include meaningful text shown in the image, describe relevant context, and omit decorative detail. Do not stuff keywords or begin with “image of.”
Last verified: September 5, 2026.
A four-part formula
- Subject: who or what is central?
- Action: what is happening?
- Context: which setting or visual relationship matters?
- Visible text: what words must the reader know?
Example: “Bar chart comparing four AI tools. Tool A scores highest for accuracy; Tool D is fastest. Heading: Accuracy versus speed.” That is more useful than “colorful AI tools infographic.”
What to include by image type
| Image | Prioritize | Avoid |
|---|---|---|
| Photo | People, action, setting | Every color and object |
| Chart | Trend, axes and conclusion | Dumping every data point |
| Screenshot | Relevant control and state | Unrelated interface chrome |
| Text graphic | Exact essential wording | Repeating a nearby caption |
Platform-aware publishing checklist
Instagram, Threads, LinkedIn and X expose accessibility features differently, and interfaces can change. Before posting, look for “accessibility,” “alt text,” or image-edit options. Confirm the text survived scheduling or cross-posting. A scheduler that copies the caption may not transfer platform-specific alt text.
Keep the post caption readable on its own. Alt text should fill the visual gap, not hide important facts from everyone else. For multi-image posts, describe each image separately and make the sequence clear: “Slide 1 of 4,” followed by the unique information on that slide.
Mistakes that reduce usefulness
- Keyword stuffing for SEO.
- Copying the entire caption into every image.
- Writing “photo of” without adding information.
- Ignoring text embedded in the graphic.
- Adding subjective claims such as “beautiful” when appearance is not relevant.
- Letting AI invent names, identities or emotions that are not known.
Pair accessible descriptions with correctly sized assets. Use our Instagram image size guide when preparing feed and vertical formats.
FAQ
How long should alt text be?
Use the shortest description that transfers the important information. Complex charts may need a concise summary in alt text and a fuller explanation in the post or linked article.
Can AI write alt text?
It can draft a description, but the creator should verify names, text, relationships and intent. Automated vision can miss the point of a chart or screenshot.
Should hashtags go in alt text?
No. Keep discovery metadata in the caption and reserve alt text for access to the image’s meaning.
Before-and-after examples
Weak: “Screenshot of analytics.” Better: “GA4 line chart for August 21–September 2. Sessions rise from zero to a peak near 48 after Threads promotion begins.” The improved version transfers the trend and its relevant context.
Weak: “Woman at computer.” Better: “A video editor compares two vertical exports on a laptop; the left preview clips the subtitles and the right keeps them above the interface controls.” Do not infer the person’s identity, emotion or disability unless that information is known and relevant.
Team review checklist
- Read the description without viewing the image.
- Confirm all visible words and numbers.
- Remove redundant decorative detail.
- Check every image in a carousel separately.
- Verify the publishing tool retained the description.
