Simple Rules for Writing Alt Text That Helps

8 min read

Last updated November 12, 2026

Alt text is a short written description of an image. Screen readers read it aloud, so people who cannot see the picture still understand it.

Good alt text says what matters about the image in a few words or a short sentence. Decorative images get none at all.

These simple rules will help you write alt text for websites, blogs and social media posts.

The Core Rules in One Table

Rule	What to do
Be brief	Use a few words or a short sentence
Describe the meaning	Say what the image shows and why it is there
Skip “image of”	Screen readers already announce an image
Include text in the image	Repeat any important words shown in it
Describe the action for links	Say where a linked image goes
Leave decorative images empty	Use an empty alt so readers skip them

Key Takeaways

Alt text helps blind and low-vision readers understand images.
Keep it short and focused on what matters.
Never start with “image of” or “picture of”.
Linked images need alt text that names the action.
Purely decorative images need empty alt text.

Quick links

What alt text is for
How to write it step by step
Alt text for different image types
Good and bad examples
Alt text on social media
Alt text and search
Write alt text in seconds
Frequently asked questions

What Alt Text Is For

Millions of people use screen readers to browse the web. When the software reaches an image, it reads the alt text instead.

Without alt text, the reader may say only “image” or read a file name. That leaves a gap in the story.

Alt text also appears when an image fails to load. Slow connections and broken links happen to everyone.

Search engines read it too. Clear alt text helps them understand what each image shows.

Good to know. Alt text is not a caption. A caption is for every reader, while alt text describes the image for people who cannot see it.

How to Write Alt Text Step by Step

The World Wide Web Consortium (W3C) sets web standards. It offers an alt decision tree for tricky cases, and these steps follow its logic.

Ask why the image is on the page.
Check whether the image is only decoration.
If it links somewhere, describe where it goes.
If it contains words, include those words.
Otherwise, describe the subject, action and setting briefly.
Read the page aloud with your alt text to test it.

Context changes the answer. The World Wide Web Consortium (W3C) images tutorial gives a bird photo as an example.

A park website may need only a brief note. A bird-watching site may need far more detail.

1,000The number of characters X allows for each image description, per the X help center.

That limit is generous, but short still wins. Most images need far fewer words.

Alt Text for Different Image Types

Informative images

Photos and illustrations that add meaning need a short description of that meaning. Focus on the detail that matters for the page.

Decorative images

Borders, background patterns and mood photos that add nothing get an empty alt attribute. Screen readers then skip them quietly.

Functional images

A logo that links home or an icon inside a button needs alt text that names the action. “Search” beats “magnifying glass icon”.

WebAIM is a respected accessibility group. Its alternative text guide says to avoid “link to” or “click here” in alt text.

Images of text

If an image shows words, such as a quote card, put those words in the alt text. Better yet, use real text on the page when you can.

Charts and complex images

A short alt text can name the chart. Then give the full data or a summary in nearby text, so everyone gets the same information.

Do you add alt text to your images today?

Always
Sometimes
Never
Not sure

Good and Bad Alt Text Examples

Image	Weak alt text	Better alt text
A dog on a beach	Image of dog	Golden retriever running along a sandy beach at sunset
Product photo	IMG_4021	Yellow raincoat with a hood and front pockets
Search icon button	Magnifying glass	Search
Quote card	Quote	Start where you are. Use what you have.
Decorative swirl	Swirl design	Leave empty

The better versions say what a sighted reader would notice first. They skip filler words and stay focused.

File names and camera codes are never good alt text. Always replace them with real words.

X

Tap the “+Alt” button on each picture before posting, type your description and tap Done. The X help center notes that videos cannot have descriptions.

Instagram

Instagram creates automatic alt text with object recognition, as its alt text help page explains. You can replace it with your own words in the advanced settings.

Your own text is usually far better. The automatic version often says only “may be an image of one person”.

Facebook, LinkedIn and Pinterest

These apps also let you add or edit alt text when you upload a photo. Look for “alt text” or “edit” on the image before you post.

Quick tip. Write alt text at the same moment you write the caption. It takes ten extra seconds once it becomes a habit.

Alt Text and Search

Search engines use alt text to understand images. A clear description can help your pictures appear in image search.

Use your main keyword only when it fits naturally. “Vegan chocolate mug cake topped with raspberries” works, while a list of keywords does not.

Keyword stuffing hurts readers and looks spammy to search engines. Always write for the person first.

Working on a blog post? Our guide to writing search engine optimization (SEO) titles covers the rest of the page.

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Alt Text for Product Photos and Shops

Online shops rely on photos to sell. Shoppers who use screen readers need those details in words.

Describe what a buyer would want to know at a glance. Color, style, material and key features matter most.

Product	Helpful alt text
Running shoe	White running shoe with a blue sole and mesh upper
Coffee mug	Matte black ceramic mug with a wooden handle
Backpack	Green canvas backpack with two side pockets

Give each photo of the same product its own alt text. A side view and a back view show different things, so describe each one.

Avoid repeating the full product name in every image. The page title already says it, so focus on what each photo adds.

Test Your Alt Text With a Screen Reader

The best check is to listen. Most phones and computers include a free screen reader.

On iPhone, turn on VoiceOver in the accessibility settings.
On Android, turn on TalkBack in the accessibility settings.
On Windows, try Narrator, which comes built in.
On a Mac, press the shortcut for VoiceOver.

Close your eyes and let it read your page. If an image description leaves you confused, rewrite it.

Listen for repeats too. If the alt text repeats the caption right below it, one of them is doing no work.

Testing takes only a few minutes per page. Do it once, and you will notice weak alt text everywhere you browse.

Common Alt Text Mistakes

Starting with “image of” or “photo of”.
Using file names like IMG_4021.
Writing long paragraphs for simple photos.
Stuffing keywords into every image.
Describing decorative images that add nothing.
Adding details you cannot see in the image.

Accuracy matters most. Describe only what is truly there, without guessing feelings or adding facts.

Write Alt Text in Seconds

Finding the right few words takes practice. The free Postlume alt text generator gives you a strong start.

Describe your image in plain words and add a keyword if you like. You get a short version and a search-friendly version to copy.

Your picture is never uploaded, because you only type a description. The Digieh AI option adds a detailed version too.

Preparing images for your site? The AI Background Remover cleans product photos, and our guide to reducing photo size in kilobytes (KB) keeps pages fast.

Captions still matter for sighted readers. Write those with the description generator.

Your Alt Text Checklist

Decide if the image is decorative
Describe the main subject and action
Include any important text in the image
Name the action for linked images
Keep it short and accurate
Read it aloud to test it

Try this today. Pick three images on your website or profile and write fresh alt text for each. Read them aloud with your eyes closed.

Test Yourself

What alt text should a purely decorative image have?

A long description
The file name
An empty alt attribute

Decorative images get empty alt text so screen readers skip them.

What should alt text for a search button icon say?

Search
Magnifying glass icon
Image of a button

Functional images need alt text that names the action, not the look.

Frequently Asked Questions

How long should alt text be?

Usually a few words or a short sentence. Complex images may need more detail in nearby text.

Is alt text the same as a caption?

No. A caption is for everyone, while alt text describes the image for people who cannot see it.

Does every image need alt text?

Every meaningful image does. Decorative images should have an empty alt attribute.

Does alt text help search rankings?

It helps search engines understand images and can help image search. Write it for people first.

Conclusion

Good alt text is short, accurate and focused on why the image is there. Decorative images get none, and linked images name their action.

Your next step is simple. Try the free Postlume alt text generator on the next image you post.

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Editor’s Note

This guide is accurate as of November 12, 2026. It follows guidance from the World Wide Web Consortium (W3C), WebAIM, the X help center and Instagram Help.

Platform features can change. We will update this page when alt text tools or guidance change.

Spot an error in this article? Please contact us at support@digieh.com or read our Corrections Policy.

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