Alt text for social media is a short written description of an image that screen readers announce to people who cannot see it. Good alt text states what matters in the image in one or two plain sentences, includes any text shown, and skips phrases like "image of." Pair it with captions on video for broader access.
Key takeaways
- Alt text for social media should describe what is visible and why it matters to the post, in roughly one or two sentences, not a keyword list.
- Video needs captions or a transcript so people who are deaf, hard of hearing or watching with sound off can follow it.
- Small habits, such as CamelCase hashtags, sparing emoji and readable contrast, make posts easier to use for everyone.
- AI-suggested alt text is a starting point only, because a person must check it against the image.
What alt text is and who it helps
Alt text (alternative text) is a written description attached to an image so that people using screen readers hear what the image shows. Screen readers are tools that read on-screen content aloud. Blind and low-vision people use them, along with some people with cognitive or learning differences.
The benefits reach further. Alt text can also display when an image fails to load, and some people find descriptions useful when they are on a slow connection. Writing it forces you to ask what the image is for, which tends to improve the post itself.
Most major platforms provide a place to add alt text. Instagram, X, LinkedIn, Threads, Bluesky, Facebook and Pinterest each have a field or setting for it, though names and menu locations differ and change. Pinterest, for example, allows alt text of up to 500 characters. If a platform offers no field, put the key description in the caption instead.
How to write alt text that helps
Good alt text answers one question: what would someone need to know to understand why this image is here? Follow these steps.
- Decide the image's job. Is it showing a product, a person, data, a mood or a joke? The job determines what to mention.
- Describe what is visible and relevant. Name the subject, action, setting and any detail the post depends on.
- Include any text in the image. If a graphic says "Sale ends Friday," the alt text should say so.
- Keep it short. One or two sentences is usually enough. Long descriptions belong in the caption.
- Skip the prefix. Screen readers already announce that it is an image, so "Photo of" and "Image of" waste words.
- Avoid keyword stuffing. Alt text is for people first. Naturally mentioning a product name is fine, but a list of search terms is not.
- Mark decoration honestly. If an image adds nothing, such as a purely decorative divider, a short description is still better than something misleading.
Examples
Weak: "Coffee."
Better: "A hand pouring steamed milk into a white cup, making a leaf pattern in the coffee."
Weak: "Chart."
Better: "Bar chart of monthly sign-ups rising from January to June, with the biggest jump in April."
Treat the numbers in any such description as your own. Describe the chart as it actually looks, and if the data matters, put the key figures in the caption as text.
Images that contain text
Avoid putting the entire message in an image where you can. If you post a quote graphic, an infographic or a screenshot, repeat the text in the caption or alt text. That also helps people who zoom, translate or search.
Captions and transcripts for video
Captions are on-screen text of spoken words and relevant sounds, and they help people who are deaf or hard of hearing, people in noisy or silent settings, and viewers who speak another language. Many people watch with sound off, so captions help reach them too.
You have a few options, depending on the platform:
- Platform auto-captions. Many platforms can generate captions automatically. Always review them, since names, jargon and accents are easy to get wrong.
- Caption files. Where a platform supports uploading one, such as YouTube, a reviewed caption file gives you full control.
- Burned-in captions. Text added in your video editor works everywhere, but viewers cannot turn it off or resize it, so keep it large, high contrast and away from interface elements.
- Transcripts. For longer videos and audio, link to a transcript in the description or on your website.
Describe important visuals, too. If a video relies on something shown rather than said, such as a product demo, say what is happening in the audio or the caption.
Other small accessibility habits
Accessibility is a set of small choices. Add the ones below to your posting checklist.
- Use CamelCase in multi-word hashtags, such as #SocialMediaTips instead of #socialmediatips, so screen readers can read each word separately.
- Limit emoji. Screen readers announce each one by name, so a string of 10 becomes noise. Put emoji after the text and avoid using them as bullets.
- Keep hashtags and mentions at the end where they do not interrupt reading.
- Choose readable contrast and size for text over images. Avoid thin fonts on busy backgrounds.
- Avoid decorative Unicode "fancy fonts." They are often read letter by letter or skipped by screen readers.
- Write in plain language and break long captions into short paragraphs.
- Avoid flashing or rapidly strobing effects in video.
- Put links in plain text and say what they lead to.
Build accessibility into your workflow
Accessibility is easier when it is part of the process, not a final check. Add a line to your content brief or approval checklist: "alt text written, captions reviewed, hashtags in CamelCase." For teams, assign one person to check these before sign-off. For a solo creator, keep the checklist beside your scheduler.
Write alt text when you pick the image, not at the moment of publishing, when you are in a hurry. If you keep a media library, store the alt text with the asset so it can be reused on future posts, and edit it for context when the same image appears in a different post.
If you use AI to draft descriptions, check them against the image. A tool can misread what is shown, miss text or add details that are not there. Treat the draft as a starting point and correct it.
Frequently asked questions
What is alt text for social media?
Alt text for social media is a brief written description of an image that screen readers read aloud. It helps blind and low-vision users understand images in posts.
How long should alt text be?
One or two plain sentences is usually enough. If an image needs a longer explanation, such as a detailed chart, summarise it in the alt text and put the full detail in the caption.
Do I need captions on every video?
It is a good habit. Captions help deaf and hard of hearing viewers, people watching without sound and viewers who prefer reading. Review auto-generated captions before you publish, since they can contain mistakes.
Is AI-generated alt text good enough to publish as is?
Not without a check. AI descriptions can miss context, misread text or invent details, so read each one against the image and edit it before publishing.
How MultiPost Studio helps
MultiPost Studio has an alt text field for each image in the composer and the media library, so descriptions are stored with the asset. An AI alt-text suggestion button gives you a starting draft, which is based on the file name and the post title and should be replaced with an accurate description of the actual image. See the features overview for the full composer workflow.