Editorial

How to write alt text for social media images and why it matters

Learn how to write clear, accessible alt text for Instagram, LinkedIn, and web images. A practical guide covering what to include, what to skip, and how to make it part of your workflow.

Alt text is the single most skipped field in social media publishing, and it takes less than thirty seconds to fill in.

Every image you post on Instagram, LinkedIn, or your website can carry a short text description that screen readers announce to visually impaired users. That same description helps search engines understand what the image shows, which feeds into image search rankings and page relevance.

Despite being quick to write and high in impact, most posts go out with the alt text field blank. The usual reasons are habit, uncertainty about what to write, or not knowing the field exists. All three are fixable.

This guide covers how to write useful alt text, what to include and what to leave out, the character limits that matter, and how to build the habit into your publishing workflow.

What alt text does and who it helps

Alt text (alternative text) is a short written description attached to an image. When a screen reader encounters the image, it reads the alt text aloud so the listener understands what the image shows without seeing it.

Beyond accessibility, alt text serves a second audience: search engines. Google, Bing, and other crawlers cannot see images the way humans do. They rely on alt text, surrounding copy, and file names to determine what an image depicts and how relevant it is to a search query.

On social platforms, alt text also appears as fallback text when an image fails to load. It is a small, invisible layer of polish that signals professionalism and care.

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How to write good alt text in practice

Good alt text is specific, concise, and describes what matters most about the image. It should give a screen reader user enough context to understand the image's role in your post without restating the caption.

The most common mistake is writing alt text that is too vague. Saying 'photo of a meeting' is less useful than 'four people reviewing a whiteboard with a content calendar drawn in marker'. The second version helps a listener picture the scene.

Describe the subject and action Start with what is in the image and what is happening. A person speaking at a podium, a flat lay of skincare products, a chart showing engagement growth.
Include relevant context If the setting, colours, or text in the image matter to understanding the post, include them. If they do not, skip them.
Keep it under 125 characters when possible Most screen readers handle longer alt text, but shorter descriptions are easier to listen to and less likely to be cut off on certain platforms.
Do not start with 'image of' or 'picture of' Screen readers already announce that the element is an image. Starting with those words is redundant and wastes characters.
Skip decorative images If an image is purely decorative and adds no information (a divider line, a background gradient), mark it with an empty alt attribute so screen readers skip it entirely.

Alt text on Instagram, LinkedIn, and the web

Each platform handles alt text slightly differently, but the core principles are the same. The main variation is where you find the field and whether it has a character limit.

Instagram

Hidden under Advanced Settings

When creating a post, tap Advanced Settings, then Write Alt Text. Instagram also auto-generates alt text using object recognition, but the auto-generated version is almost always too generic to be useful. Write your own.

LinkedIn

Available on image posts and articles

When you add an image to a LinkedIn post, click the alt text icon on the image preview. LinkedIn does not auto-generate alt text, so if you skip it, the image has no description at all.

Websites and blogs

The alt attribute on the img tag

Every CMS has an alt text field in the image upload dialog. This is also where search engine image indexing is strongest, so include relevant keywords naturally without stuffing.

Making alt text part of your publishing workflow

The easiest way to make alt text consistent is to write it at the same time you write the caption. If you batch your content creation, add an alt text column to your content calendar or planning spreadsheet.

Using a guided alt text tool can speed up the process. Instead of staring at a blank field, you answer short prompts about the subject, action, and setting, and the tool assembles a description you can refine and copy.

Over time, writing alt text becomes automatic. The mental cost drops to near zero once you have a pattern: subject, action, relevant context, done.

Alt text is one of the smallest changes you can make to your publishing process with one of the widest impacts. It improves accessibility for the estimated 2.2 billion people worldwide with a vision impairment, it strengthens your image SEO, and it signals to platforms and audiences that your content is built with care.

Start with your next post. Write one sentence describing what the image shows, check the character count, and paste it in. That is the entire habit.

Images described. Now schedule the post.

Once your images have proper alt text and captions, schedule them across Instagram, LinkedIn, and every platform from one calendar.

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