Write better alt text

Alternative text, or alt text, is the written equivalent of an image for people who can't see it: screen reader users, people on slow connections, and search engines. Writing it well is less about rules and more about one question: why is this image on the page? This guide explains how to answer that question and how to use the Image alt-text generator as a starting point.

Start with the image's purpose

The same photo can need different alt text in different places. Decide which of three cases you are in.

Informative images

They add information that the surrounding text doesn't already give. Describe what matters in that context.

Example: on a recipe page, a photo of a finished dish might have the alt text "A bowl of tomato soup topped with basil and a swirl of cream".

Functional images

They act as a button or link, like a magnifying-glass icon that opens search. The alt text should say what happens, not what the picture looks like: "Search", not "Magnifying glass".

A tool can't know where your link goes. Give it page context, such as "This icon opens the search box", and check the result.

Decorative images

They add no information, like a flourish between sections. These should have an empty alt attribute, alt="", so screen readers skip them. The tool explains this when you choose Decorative.

Keep it as short as the context allows

There is no universal character limit. The length options in the tool (short, medium, long) are guidance. Short is fine for a simple photo with a caption next to it. Longer descriptions suit images that carry information, such as a chart. For complex images, put the full explanation in the page text and keep the alt text brief.

Habits that make alt text better

• Don't begin with "image of" or "picture of": screen readers already announce an image.
• Describe, don't interpret feelings that aren't visible.
• Avoid keyword stuffing. Alt text written for people helps search engines too; alt text written for search engines helps nobody.
• Don't assume identity, age or other personal traits. Say what's visible, and name people only when you know and it matters to the content.
• Include text that appears in the image if it's important.

A worked example

Context: a blog post about breakfast ideas, with a photo of oranges in a bowl.

• Too long: "Image of a beautiful, fresh, juicy, delicious bowl of oranges, fruit, citrus, breakfast, healthy food, vitamin C on a table."
• Better: "A ceramic bowl of oranges on a wooden table beside a sunny window."

(Example written for this guide.)

Using the tool

1. Upload the image.
2. Pick the purpose and, when useful, add a sentence of page context.
3. Choose a length preference.
4. Read the suggestion in the context of your page, and edit it.

The tool also gives an accessibility note and, when an image is complex, an extended description you can place in the page text.

A final check

Read the page aloud with the alt text in place of each image. If it still makes sense and nothing is repeated or missing, you're done. For high-stakes pages, test with a real screen reader or ask someone who uses one.