How to Make Social Media Posts Accessible with Effective Alt Text
Social media is visual by design. Photos, screenshots, infographics, and memes drive engagement across every platform. But when you skip alt text, you're excluding millions of people who use screen readers from participating in conversations.
Alt text on social media isn't just a checkbox for compliance—it's how you make your content accessible to blind and low-vision users, help people on slow connections, and improve discoverability. This guide covers platform-specific best practices for Bluesky, LinkedIn, and Instagram so you can write alt text that actually works.
Why Social Media Alt Text Is Different
Alt text on social platforms serves the same core purpose as alt text on the web, but the context changes how you should write it.
Social posts are conversational. Your alt text should match the tone of your post. If you're joking, the alt text can be casual. If you're sharing professional insights, keep it professional.
Context matters more. The same photo needs different alt text depending on your caption. A sunset photo on a travel account might focus on location details. The same sunset in a motivational post needs alt text that supports the message.
Character limits vary. Some platforms have generous alt text limits (1,000+ characters), while others cap at 100. Know your platform's constraints.
Screenshots and text-heavy images are common. Social media is full of tweets, messages, and text graphics. Your alt text must include all visible text for screen reader users.
Best Practices for Bluesky
Bluesky allows up to 1,000 characters for alt text and makes it easy to add during composition.
How to Add Alt Text on Bluesky
When composing a post with an image, click the "ALT" badge on the image thumbnail. A dialog opens with a text field for your description.
Bluesky Alt Text Best Practices
Match your post's tone. Bluesky culture is conversational and informal. Your alt text can be too.
Example post: "just planted my first garden and i'm unreasonably proud of these tomatoes"
Alt text: "Hands holding three large red tomatoes in a backyard garden with raised beds visible in background"
Include text from screenshots. Bluesky is full of screenshot threads. Every word needs to be in your alt text.
Example: Screenshot of a tweet
Alt text: "Tweet from @username: 'The problem with debugging is that you have to understand the code you wrote six months ago when you were a different person.'"
Describe memes completely. Meme formats are visual jokes. Describe both the image structure and the text overlays.
Example: Distracted boyfriend meme
Alt text: "Distracted boyfriend meme. Man in red shirt looking back at woman in red dress while his girlfriend in blue looks annoyed. Top text: 'Me.' Woman he's looking at: 'Starting a new project.' Girlfriend: 'Finishing my existing projects.'"
Keep context from your caption in mind. If your post already describes what's happening, use alt text to add details, not repeat yourself.
Post caption: "New coffee shop opened downtown with the best matcha latte I've ever had"
Alt text: "Green matcha latte with latte art in white ceramic cup on wooden table, natural light from window visible"
Best Practices for LinkedIn
LinkedIn allows 300 characters for alt text. Professional context means your descriptions should be clear and informative.
How to Add Alt Text on LinkedIn
When uploading an image to a post, click the pencil icon or "Edit" button on the image preview. The alt text field appears in the editing dialog.
LinkedIn Alt Text Best Practices
Be professional and specific. LinkedIn is a professional network. Your alt text should reflect that.
Example: Photo at a conference
Alt text: "Three software engineers reviewing code on laptop at Tech Summit 2024, conference badges visible"
Describe charts and data visualizations clearly. LinkedIn posts often include graphs and metrics. State the key insight, not every data point.
Example: Bar chart showing growth
Alt text: "Bar chart showing quarterly revenue growth from Q1 to Q4 2024, increasing from $2M to $5.5M"
Include visible text from slides and presentations. If you're sharing presentation screenshots, include the slide title and key bullet points.
Example: Presentation slide
Alt text: "Slide titled 'Q4 Strategy Priorities' with three bullet points: Expand enterprise sales team, Launch mobile app beta, Improve customer onboarding experience"
Add context for headshots and team photos. Identify people when relevant, describe professional settings.
Example: Team photo
Alt text: "Marketing team of six people standing in modern office space, floor-to-ceiling windows with city view in background"
Don't repeat your post caption verbatim. If your caption says "Excited to share our new product launch," your alt text should describe the product image, not announce excitement.
Best Practices for Instagram
Instagram allows up to 100 characters for alt text and auto-generates descriptions for images without manual alt text. The auto-generated descriptions are usually inadequate.
How to Add Alt Text on Instagram
When creating a post: After selecting your photo and filters, tap "Advanced Settings" at the bottom of the caption screen. Tap "Write Alt Text" and enter your description.
For existing posts: Go to the post, tap the three dots menu, select "Edit," then tap "Edit Alt Text."
Instagram Alt Text Best Practices
Work within 100 characters. Instagram's limit is strict. Be concise but specific.
Example: Product photo
Good: "Woman wearing oversized cream sweater and black jeans, sitting on gray sofa"
Bad: "Beautiful lifestyle shot of a woman modeling our new fall collection in a modern minimalist living room with natural light"
Focus on the visual, not the vibe. Describe what's in the image, not the feeling you want it to convey.
Vague: "Cozy autumn aesthetic"
Specific: "Pumpkin spice latte with cinnamon stick on wooden table with fall leaves"
Include relevant emoji descriptions. If the caption uses emojis to convey meaning, describe them in alt text when they add context.
Post caption: "New studio space ✨🎨"
Alt text: "Bright art studio with paint-covered easel, canvases stacked against white wall, skylight overhead"
Don't over-describe aesthetic photos. Instagram leans heavily on mood and style. Focus on concrete details, not abstract interpretations.
Unnecessary: "Ethereal morning light creating a dreamlike atmosphere"
Better: "Empty beach at sunrise, pink and orange sky reflected in wet sand"
Include text from graphics. Instagram is full of quote graphics and infographics. Screen reader users need access to that text.
Example: Motivational quote graphic
Alt text: "Beige background with black text reading: 'Progress over perfection'"
Common Mistakes to Avoid on Social Media
Using Generic Descriptions
"Image" or "photo" tells screen reader users nothing. Be specific.
Bad: "Image"
Good: "Chocolate chip cookies cooling on wire rack"
Starting with "Image of" or "Photo of"
Screen readers already announce it's an image. Don't waste characters.
Unnecessary: "Image of sunset over ocean"
Better: "Sunset over ocean with orange and pink clouds"
Describing Feelings Instead of Facts
Alt text should describe what's visible, not how you want people to feel about it.
Vague: "Inspiring workspace"
Specific: "Standing desk with dual monitors, succulent plant, and notebook"
Skipping Text from Screenshots
If your image has text, that text must be in the alt text. All of it.
Writing Alt Text for the Algorithm
Don't stuff keywords into alt text hoping for better reach. Write for humans using screen readers.
Bad: "Coffee morning coffee latte art best coffee shop coffee beans artisan coffee"
Good: "Cappuccino with leaf latte art pattern in white cup"
Platform Comparison: Alt Text Features
| Platform | Character Limit | Auto-Generation | Editing After Post |
|---|---|---|---|
| Bluesky | 1,000 | No | Yes |
| 300 | No | Yes | |
| 100 | Yes (poor quality) | Yes | |
| Mastodon | 1,500 | No | Yes |
| 255 | Yes (poor quality) | Limited |
How Alt Kit Simplifies Social Media Alt Text
Writing thoughtful alt text for every post takes time. Alt Kit makes it effortless:
- One-click generation directly in your posting flow—no copy-paste needed
- Platform-aware descriptions that match character limits and context
- Perfect OCR for screenshots, memes, and text graphics
- Works on Bluesky, LinkedIn, Instagram, Mastodon, and Facebook
The extension is free to use. Bring your own API key from Google, OpenAI, or Anthropic, or subscribe to Alt Kit's hosted plan for instant access with no setup.
The Bottom Line
Alt text on social media isn't optional. Every image without alt text excludes someone from the conversation.
Bluesky gives you space to be descriptive. LinkedIn expects professionalism and clarity. Instagram demands brevity. But the core principle stays the same: describe what's visible in a way that makes sense for screen reader users.
You can write it manually, or you can let Alt Kit handle it with one click. Either way, make it standard.
Try our generator to get started.
Frequently Asked Questions
What is alt text and why does it matter?
Alt text (alternative text) is a written description of an image that screen readers read aloud to users who are blind or have low vision. Without alt text, these users miss the context and meaning of images in your posts. Over 2
billion people worldwide have some form of vision impairment.
How long should alt text be?
It depends on the platform. Bluesky allows up to 1,000 characters, LinkedIn caps at 300, and Instagram limits you to 100. A good rule: be as concise as possible while still conveying the essential information. Most images can be
described well in 1-2 sentences.
Should I start alt text with "Image of" or "Picture of"?
No. Screen readers already announce that something is an image, so starting with "Image of" is redundant. Jump straight into the description: "Golden retriever catching a frisbee at sunset" not "Image of a golden retriever catching a
frisbee."
What about images with text in them?
Include the text in your alt text. Screenshots of tweets, memes with captions, and infographics all contain text that screen reader users can't access otherwise. Transcribe the important text as part of your description.
Do decorative images need alt text?
Purely decorative images (borders, spacers, background patterns) can have empty alt text. But on social media, most images add meaning to your post and should be described. When in doubt, add alt text.
Can AI write alt text for me?
Yes. Tools like Alt Text Creator use AI to generate descriptive alt text from your images. This is especially helpful for complex images or when you're short on time. You can always edit the generated text to add context the AI
might miss.
Ready to make your social posts accessible? Install the free Alt Kit extension and start creating alt text for every platform with one click.
Photo by Collabstr