Writing Alt Text That Actually Helps Readers

Every picture in a post has a second, quieter life as words. Alt text, short for alternative text, is the description attached to an image in the page’s code. Most readers never see it. For some readers it is the only version of the picture they get: people using screen readers, people on a slow connection where the image fails to load, and anyone whose browser is set not to show images at all.

For a visual blog, that matters a great deal. If the photos carry half the story, the alt text has to carry that half for everyone who cannot see them. This is how we think about writing it well, in plain terms.

What alt text is for

Alt text answers one question: what would a reader miss if this image were not here? It is not a title, not a caption and not a place for keywords. It is a stand-in. Read the sentence before the image, then the alt text, then the sentence after. If the three flow together and nothing important has gone missing, the alt text is doing its job.

That test also explains why there is no single right length or formula. The same photo of a bowl of noodles might need different alt text in two different posts. In a recipe, the reader may need to know that the broth is clear and the herbs go on last. In a travel story, the reader may need to know that the bowl sits on a plastic stool at a pavement stall. The image is the same; what it contributes to the story is not.

Describe what matters, in order

Good alt text usually starts with the most important thing and stops before it runs out of usefulness. A few habits help:

• Lead with the subject. “Grandmother’s hands shaping rice cakes on a banana leaf” puts the point first. “A photo taken in the kitchen last Tết showing…” makes the listener wait.
• Include the detail the story relies on. If your paragraph says “you can see why the bridge floods”, the alt text should mention the water line on the pillars.
• Skip “image of” and “photo of”. Screen readers already announce that it is an image. Say what is in it.
• Keep it to a sentence or two. Long descriptions are tiring to listen to. If a picture genuinely needs a paragraph, that paragraph probably belongs in the body text, where every reader can benefit from it.
• Write in your own voice. Alt text is part of your post. It can be warm and specific rather than clinical, as long as it stays accurate.

A few examples, better and worse

It helps to see the difference side by side. Imagine a post about restoring an old bicycle.

• Weak: “Bicycle.” True, but it tells the reader nothing the sentence around it has not already said.
• Weak: “Vintage bicycle restoration DIY project old bike repair.” This is a list of search terms, not a description, and it is unpleasant to hear read aloud.
• Better: “The bicycle frame stripped back to bare steel, with rust still pitting the rear fork.” Now the reader knows what stage the project is at and what problem comes next.

Or a post about a hike:

• Weak: “Beautiful view from the top.” Beautiful to whom, and of what?
• Better: “Looking down from the summit at terraced rice fields, a thin path winding between them toward the village.” The listener gets the shape of the landscape and a sense of how far they have climbed.

Notice that the better versions are not dramatically longer. They are simply more specific about the part that matters.

Text, charts and pictures of words

Some images are mostly words: a screenshot of a menu, a hand-lettered sign, a page from a notebook, a simple chart. These need special care, because the information is locked inside the picture.

If the words matter to the story, put them in the alt text, or better still, in the body of the post where everyone can read and copy them. A recipe card photographed on the kitchen counter is lovely to look at; the ingredients typed out underneath are what readers will actually use. For a chart, describe the one thing it shows (“prices rose every month from March to June”) rather than reading out every number.

When an image needs no description

Not every picture carries information. A decorative divider, a texture used purely for mood or a second near-identical shot of the same scene may add nothing a listener would miss. In HTML, the convention for a purely decorative image is an empty alt attribute, which tells assistive technology to skip it. MDN’s reference page for the img element explains the details if you are curious.

Be honest with yourself about this, though. On a visual blog, most photos are there because they show something. If you find yourself labelling many images as decorative, it may be a sign that some of them could be cut, a question we come back to in our note on sequencing images in a post.

Alt text and captions are different jobs

It is easy to blur the two, so it is worth saying plainly. A caption is visible to everyone and adds something the picture does not show: a name, a date, a bit of context, a wry aside. Alt text is a substitute for the picture itself, for people who cannot see it. A screen-reader user will often hear both, so they should not repeat each other word for word.

A simple way to keep them apart: let the alt text describe what is in the frame, and let the caption say what is outside it. We go further into the second half in captions that add something the photo can’t.

Make it part of the routine

Alt text is easiest to write at the moment you place the image, while you still remember why you chose it. Left until the end, it turns into a chore, and chores get rushed. A habit we suggest: as you add each picture, ask yourself what you wanted the reader to notice in it, and write that down in a sentence. That sentence is usually your alt text, nearly finished.

It costs a few seconds per image. In return, the whole of your story reaches the whole of your audience, which, for writers who think in pictures, is rather the point.