How to Write Alt Text That Makes Your Social Posts Work for Everyone

Alt text is a written description of an image, read aloud by screen readers so that people who are blind or have low vision know what a post shows. Writing it well means describing what matters in a photo or graphic, in plain language, without turning it into a hashtag dump. HW Media Management put this guide together because alt text gets treated as an afterthought on most accounts, when it takes less effort than writing the caption itself.

What alt text actually does on a social post

Every major platform lets you attach a text description to an image when you post it. A screen reader reads that description aloud, so someone who can't see the image still knows there's a dog on a beach, a product shot on a white background, or a quote graphic with three bullet points.

Without it, a screen reader either skips the image entirely or reads out the file name, something like "IMG4821.jpg". That tells a follower nothing and quietly excludes them from a post everyone else can read.

Why alt text matters for accessible social media posts, not just compliance

Treating accessible social media posts as a box-ticking exercise misses the point. A follower who relies on a screen reader is still a customer, still a potential client, still someone deciding whether to trust a brand. Good alt text is the difference between them following the whole conversation and following half of it.

There's a practical side too. Some platforms use alt text as another signal for what an image contains, alongside the caption and any text layered onto the graphic. Writing it properly supports how the post performs, even though it was never built as a ranking trick.

Writing alt text that describes the image, not the caption

The most common mistake is repeating the caption word for word in the alt text field. The caption carries the hook, the voice, the call to action. The alt text has one job: describe what's visually in the frame.

• Name the subject first: a person, product, graphic, or scene.
• Add the detail that matters to understanding the image, not every detail.
• Mention text that appears in the image itself, such as a headline on a quote card.
• Skip phrases like "image of" or "picture of" – the screen reader already announces it's an image.

A photo of a barista steaming milk doesn't need "a lovely candid shot of our wonderful team member". It needs "a barista steaming milk behind a counter, espresso machine in the background". That's enough for someone to picture the scene and move on.

A short method for any image

1. Look at the image for five seconds and note the first three things you'd mention to a friend.
2. Write one sentence using those three things, subject first.
3. Add any visible text from the graphic, in quotation marks.
4. Cut anything that describes feeling rather than content, such as "stunning" or "amazing".
5. Read it back without looking at the image – if it still makes sense, it's ready.

Handling graphics with text on them

Quote cards, carousel slides and infographics carry their own words, and those words need to be in the alt text too, because a screen reader can't read pixels. If the graphic says "5 ways to grow your email list", that line belongs in the description, followed by a short note on any icons or imagery around it.

Image descriptions for accessibility across different post types

Different formats call for a different level of detail. A single product photo needs a short, direct line. A carousel of six slides needs a separate description for each one, because a reader working through the post one swipe at a time needs each slide to stand on its own.

For a chart, the goal is the takeaway, not a transcription of every axis label. If you're already thinking hard about how a graphic communicates, it's worth reading up on what sentiment analysis measures, since the two skills (reading what an image says and reading what a comment means) draw on the same instinct for context.

Where to add alt text on each platform

Most platforms hide the alt text field inside the posting flow rather than putting it front and centre. On image-led platforms, it usually sits under an "accessibility" or "edit alt text" option before you publish. On others, it's buried in advanced settings, which is exactly why it gets skipped.

Scheduling tools often carry their own alt text field too, separate from the caption box, so if you're managing several accounts through one dashboard, check that the field is actually being sent through to each platform and not left blank by default.

Common mistakes that undo good intentions

Stuffing alt text with keywords is the biggest one. A description written as "social media marketing digital marketing content creation tips strategy" tells a screen reader user nothing and reads as nonsense out loud. Alt text is written for a person, not scanned for terms.

• Writing alt text identical to the caption, missing the chance to add real visual detail.
• Leaving the field blank and relying on the caption alone.
• Over-describing minor details like exact colours or brand logos nobody needs to know about.
• Using the field to sneak in extra hashtags or a sales line.

If you're building out a full content calendar for the weeks ahead, it's worth adding an alt text line to the planning template itself, so it gets written alongside the caption rather than bolted on at the last minute.

Checking your alt text is doing its job

Before publishing, read the alt text out loud without looking at the image. If it makes sense on its own and gives a clear picture of what's there, it's doing what it should. If it reads like a list of tags or just repeats the caption, it needs another pass.

Alt text written for a search engine helps nobody. Alt text written for a person who can't see the image is the only version worth publishing.

Start today

You don't need a new workflow to begin, just the next post you publish.

• Open your last three posts and check whether the alt text repeats the caption.
• Rewrite one of them using the five-second method above.
• Add an alt text column to your content calendar template.
• Check where the alt text field sits on each platform you post to, so it stops getting skipped.

#Visual content #Content strategy #Content calendar #Bio optimisation

Download PDF: Alt text checklist for social posts PDF, 29 KB