Everything we know about alt-texts, when to use them, and how to craft them.

An alt-text is a description of an image that’s shown to people who can’t see the image. Alt-texts help people with little or no vision who use assistive technologies, people who have turned off images, and search engines.

It might sound obvious, but an alt-text should describe the image in case an image doesn’t display or someone has trouble seeing it. The goal of alt-text is to give the necessary information from the image at a glance. It’s best to include only the necessary information.

Man and woman using laptops at a standing table, Illustration.
Don’t Do
“People using computers.” “Man and woman using laptops at a standing table, Illustration.”
“Man in a purple shirt and woman in blue pants are typing on laptops and there’s a plant on the floor nearby.”
“Man and woman using computers, illustrated by Jane Doe © 2019.”

Take context into account. For instance, if the image above is part of a blog post about standing tables, then it’s safer to skip the part about standing tables.

Don’t start alt-texts with things like “Image of” or “Photo of.”. Screen readers add that by default. If it’s a special type of image (like an icon), you can note that at the end.

Don’t Do
“Image of a rocket.” “A rocket.”
“Illustration of a rocket.”
Photo of a rocket.”
“Icon of a rocket.” “A rocket, icon.”

End the alt-text with a period. This makes screen readers pause a bit after the last word in the alt-text, creating a natural pause before the next bit of text.

In most cases you should use an alt-text for images, but there are some exceptions where you should leave the alt-text blank.

If an image does not convey any meaning to the user, leave the alt-text blank.

<img src="rocket.svg" alt="">

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The rocket here doesn’t add meaningful information.

If an image has a label nearby, leave the alt-text blank.

<img src="leaderboard.svg" alt="">


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The nearby text here already explains what the graphic illustrates. If there was alt-text here, screen readers would repeat information to the user.

Note: In these cases, leaving the alt attribute empty (alt="") will cause a screenreader to skip over the image. Never remove the alt-attribute. When a screenreader comes to an image without an alt attribute, it will dictate the filename (Eg. “SO underscore logo dot png”).

Inside an <img> tag, add the alt-text inside the alt attribute:

<img src="image.png" alt="The alt text.">
<img src="image.svg" alt="The alt text.">

Inline SVG doesn’t support the alt attribute, so instead add two wai-aria attributes: role="img" and aria-label="The alt-text.":

<svg role="img" aria-label="the alt-text" viewBox="…"></svg>

This content was adapted from Axess Lab.