How to Write SEO-Friendly Alt Text for Images

SEO Friendly Alt Text Header

Alt text is a phrase that is thrown around a lot in SEO articles and audit recommendations, but many are still unclear about its relevance or how to implement it in a beneficial way. If this sounds familiar, this guide is going to clarify things for you. Read on to find out all you need to know about alt text and the best way to optimise your images for search engines. 

What is alt text?

Alternative text, most commonly known as alt text, is used to describe the contents of an image on a webpage. Alt text is part of the HTML and was initially created for screen readers. Screen readers are software applications that help visually impaired people use a computer. The software reads out the content from the page either via audio or braille. Since it is impossible for the machine to read an image, alternative text was inserted so that the contents, and therefore the purpose, of the image can be understood by those who cannot see it.  

How does alt text help SEO?

Similarly to screen readers, search engines cannot read or understand images, but they can understand text. So, alternative text helps Google and other search engines to understand the content of your images and therefore their relevance to the search query. In other words, alt text is a prime position for keywords.

Is it a priority?

As an experienced SEO I must be honest and say that alt text is not a priority if your website has lots of critical issues. For example, if you have a site that has weak content, confusing structure and lots of technical errors then optimising your images is not going to make much difference to your organic rankings. In this case, you should prioritise bigger problems first and look at images later. However, as alt text is an opportunity for keyword placement, there are many circumstances in which optimising your image could improve rankings. 

How do I put it into practice?

So, the best way for you to think about alt text is the same way you think about page titles or meta descriptions. Every time you upload a new image you must always add alternative text and never leave it blank. If you haven’t been doing it thus far, don’t panic – but start doing it now. 

If you audit your site and it shows you have little alt text set up for your images, then you should tackle these after you correct the main problems. Once you move on to alternative text you should prioritise first your pages, then your images on the page. For example, if you have an “About Us” page with photos of your team, you can move them to the bottom of the list since they don’t have any relevance to your SEO campaign.

Conversely, your top landing page containing images of your best selling products are extremely relevant, so should optimise them first. Another tip is to avoid distraction by the multitude of images on each page (logos and nondescript graphics etc.). Instead, focus solely on the images that provide opportunity for keyword placement. However, it’s essential that the keyword is relevant to the image. If not, this is keyword stuffing and therefore bad practice. 

How do I write good alt text?

Unfortunately, keyword stuffing in alternative text is a common mistake. In fact, once they become aware of the opportunity, SEOs can be tempted to add superfluous, keyword-rich alt text that ultimately fails to describe the contents of the image. This is known as black hat SEO and is a waste of valuable time. To avoid this pitfall, think about alternative text as the process of describing the image in the most concise way possible. In other words, keep it short and sweet. When writing alt text, keep these two questions in mind:

  1. What is the main feature of this image?
  2. How is this image relevant to my customer’s experience?

Reduce your answer to one short sentence and if there is a keyword relevant to both the image and the page it is on, use it.

Alt Text Examples

Finally, here is an example of good alternative text. Let’s say you have an image of a basketball made by Slazenger for children, and you want to rank for the keyword kids basketball. Your alt text could be “Kids Basketball by Slazenger”. It’s that simple.

Where it gets complicated is when you have multiple images of the same (or similar) things on one page. Avoid repetition. This is something I advise when optimising all types of meta data. If you have mentioned it already in the text on the page, do not repeat it again in the alt text. Try using synonyms and secondary keywords instead. After all, we want our customers to have a great user experience. Read the alt text like it’s part of the content, if it doesn’t sound good to you it won’t sound good to the customer. 

Kirsty Beth McLennan
I’m an SEO Specialist from Glasgow, Scotland. Starting out in agencies and working my way up to head of the SEO team for a large UK retailer, I have almost three years of experience in digital marketing. When I’m not working I enjoy travelling, reading, and drinking wine with friends.