How to write good alt text

Everywhere you go on the internet, it’s awash with images. It could be anything from a meme of a kitten doing something cute or an important statement from the government.

But what if you’re blind? How can we make the visual world of the internet more accessible for people like me?

Well, fortunately, there is a really simple thing we can all use when posting pictures online. It’s called alt text.

What is alt text?

Alternative (or alt) text is literally a description of an image that will be read out by a screen reader.

Screen readers are specialist programmes that convert what is on the screen into speech. They’re often used by blind people like me.

By adding alt text to your images, you make them accessible for people who are using screen readers.

Some social media apps (for example, X) will even remind you when you’re posting an image to make it accessible by adding alt text. It’s really simple to do and will make a world of difference.

Why is alt text important?

“Using alt text when uploading an image means I’m included, I know what’s going on and can join in. I want to know about the cute kittens as well!”

I believe that for the most part, the internet is a force for good. It’s helped me personally remain connected to the world.

Whether that’s chatting to friends or catching up with the latest Olympics news, I’m online an awful lot.

Using alt text when uploading an image means I’m included, I know what’s going on and can join in. I want to know about the cute kittens as well!

Beyond it being the right thing to do to be more accessible and inclusive, alt text may also improve your website traffic. Good alt text can improve your ranking in search results, meaning more people are likely to find your page when they’re searching online.

How to write alt text

So what makes good alt text? Below are some top tips, based on my own experiences, for writing great alt text.

Be succinct – you don’t need to write a novel!

Good alt text should clearly set out specifically what’s in the image, so that someone using a screen reader gets the same key information that someone looking at the image will get.

But don’t go overboard with the amount of detail. You shouldn’t need to write more than one or two sentences, or 125 characters.

Give me the necessary context

I need alt text to give me enough information to fully understand the context of the image, while considering what is relevant and important.

For example, if I was posting a picture of my delicious stuffed crust pizza, unhelpful alt text would say something vague like: “Some food on a plate”.

Helpful alt text would add a bit more context: “A slice of Steven’s favourite pizza on a blue plate”.

Tell me if it’s a logo or an icon

It helps when alt text is clear about what on the page is a logo, icon or symbol signifying something.

If the image is linked to a webpage, then it’s also helpful to be told what will happen if I click the link.

For example, if your image links to the “Help” page on your website, then it would be useful for the alt text to state: “Get help”.

Don’t tell me it’s an image

One of the most common pitfalls when writing alt text is starting with “A picture of…” or “An image showing…”

You don’t need to write anything like that in your alt text. My screen reader will tell me it’s an image, so if it’s also added into the alt text, it can be quite frustrating.

Include text that’s in the image

If your image has words in it, please include the text in your alt text.

There is nothing more annoying than alt text that says something like “Statement from the Prime Minister”, but doesn’t share the content of the statement.

Recently, US president Joe Biden announced that he wouldn’t be seeking re-election in November 2024. He did this via a post on X. The alt text description provided by the White House simply stated: “A letter from President Biden”. Utterly unhelpful.

Don’t add alt text to every single image

I know, it sounds like a bit of a contradiction to everything I’ve just said. But not every image online needs alt text.

If an image is purely for decoration, and doesn’t add anything to the page in terms of information or user experience, then it’s not important for me to know about. In fact, having to read unnecessary alt text can be annoying and slow me down.

In conclusion…

Alt text is a vital tool in making the internet more accessible for people like me. Please consider using it when you next post an image, so we can all laugh at memes and keep up with the day’s news!