Selection of dice cubes with letters and dots on, on white background, with centre dice spelling out 'ALT TEXT'

How to write alt text for website images

Writing good alt text for images on your website is really important for accessibility. There is also a small advantage for search engine optimisation (SEO), but I don’t want you to do it for that reason only!

Let’s explore what alt text is and how to write this essential piece of copy to help our websites to be accessible to all, particularly those with a visual impairment.


What is alt text?

Alt text is a short written description that accompanies an image on a website. Functionality to also add text is available on other platforms too, such as when you add images to a LinkedIn post -look out for the ‘alt’ option.

Your alt text should clearly describe what the image is. It is used by reader software to help those with visual impairments to know what the images portray.

Why is it important?

Accessibility is so important and we all have a responsible to make our businesses accessible to all. This is no different for content marketing and, in particular, our website.

I’m really passionate about this. And for me, when uploading an image to my website, it really does not take much (especially when you have a good guide) to write a short description. Yet, it can make a massive difference to an individual and their access to the internet and websites that they wish to visit and explore.

The alt text can also be used by search engines to get a better understanding of a webpage’s content – both text and visual. It should never be the primary reason for including it, but by default, it does have some SEO benefits too.

Learn more here:

How can I see alt text?

Alt text can be added when an image is uploaded to a website, and can also be added retrospectively. So, there is no excuse not to do it.

It can usually be found in the ‘information’ section of each image you have uploaded to your media library or gallery, as it may be known.

Alt text can appear when you hover over an image (or sometimes the filename is shown – which also should be a clear title relating to the content of the image).

You can also right click on an image to reveal a menu (see below). Click ‘inspect’ and alongside a lot of other information, under the label ‘accessibility’, you should see the alt text for an image, if the website owner has added it.

Importantly, if it is there, the alt text will be automatically identified and read out when a webpage is visited and read out loud by specialist screen reader software, for those that need it.

ChatGPT (Open AI) open on a phone which is placed on top of an open book showing just text in background, with right click menu listing items including 'inspect' which you click to see alt text, amongst other information.
Click ‘inspect’ and then ‘accessibility’ to find the alt text for an image

What to consider when writing alt text

For accessibility

If the image serves no informational purpose and is only decorative then the advice is to leave the alt text clear. However, I wonder if this does a disservice to many webpages,where the image does add something to the content. Therefore, I think when it is decorative, but is showing something of interest, a short description is worth adding.

However, as a priority, you should always focus on writing alt text for informative images, especially those that include important data, text, numbers, figures, graphs, etc.

The text should be clear but brief – around 125-150 characters. Aim for accuracy above anything else. You can also add some context for how the image fits with the rest of the page’s content.

For search engine optimisation (SEO)

Explaining how the image fits with the page can benefit your SEO.

This should never be the priority for alt text. And a alt text description should never be written for SEO purposes to the detriment of the description for accessibility purposes.

However, if the image really does fit the context and content of a webpage, including your keywords can have SEO benefits.

A search engine will ‘read’ the alt text to get a good understanding of the complete content on a webpage. With this in mind, it is important that your description is clear.

As a side note, the search engine will also ‘read’ the file name of an image so it’s good practice to make this descriptive too – not “PN19045.jpg” for example!

How to write good alt text

Step 1 – Consider the essential information that the image conveys and what key things you need to include in the description. If the image is absolutely decorative, such as a pattern or abstract image you can use the “empty alt attribute”, which is simply alt=” ” . For accessibility, this tells a screen reader to ignore the image.

Step 2 – Write the description containing the keywords identified. You will need to be concise because the number of characters is limited to around 125 characters. So, do not waste words. You don’t have to state things like “this is a picture of” or “image contains” – go straight in.

Step 3 – Check priorities. Once you have written your first draft of alt text, just go back and put yourself in the shoes of someone who may have a visual impairment. What would be the most pertinent thing for them to know to truly understand the image? If you have any important text or numbers on the image, ensure these are included. Some detail about background or distinctive details is also helpful for visualisation. Edit as you see fit.

If you want to ‘test’ the effectiveness, you can access your own screen reader to check how the alt text sounds. You can also simply ask for feedback. Test your descriptions on people if haven’t seen the page and its images and see if they feel they match/are a good description.

However, don’t let this stop you doing it! Something is so much better than nothing. We all learn as we go.

How to cheat…

Use AI.

If you search “ai alt text generator” you will find a number of content generators that can “see images”. These can write the alt text for you.

As with all content generators, they are not perfect but can give you a starting point. They can be particularly helpful if you have a lot of images on your website and have never written a single line of alt text for any of them!

Obviously, be very wary of the T&Cs of needing to upload imagery or allowing AI software to view images. Particularly be aware if you own the copyright or the images are of people, children etc. before giving access.

Website copywriting best practice and other support

I am passionate about including alt text and considering accessibility because it is such an important ‘value add’ to my copywriting services, and it is easy enough for me to do. However, I know the difference it can make.

I see part of my role as a professional content writer of websites is to understand and offer to support my clients with every element of their written content.

This means that whilst I will happily write the main body of content I am also happy to help with ‘extras’. This includes meta descriptions, call to action buttons and alt text, so that you get a comprehensive website copywriting services.

Together, we can help make the internet a bit more accessible to all.

Learn more about my website copywriting experience and services:

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