Image Optimization and Alt Text Best Practices

Image search can generate a ton of traffic. Not all that traffic is going to be worthwhile, but in many niches you can find ways of turning that into leads, subscribers or, if nothing else, a sweet link opportunity.

However, to generate that traffic to your images, you need to understand alt text.

The purpose of alt text is to provide an alternative description for an image, specifically so that a search bot can better understand what the image is and context behind it. Additionally, alt text is a user-experience booster, providing users that can’t see, or choose not to view images within their browser, an idea of what should be in its place.

Think of it from the standpoint of a visually impaired reader. Those with visual impairments use screen readers, which are unable to portray images, but will allow the user to read the title, alt text and captions – if they are provided.

With image search providing additional means of funneling traffic to your site – all with minimal time commitment – it would be silly not to optimize your images. Below are some alt text best practices to start winning more traffic.

Image Optimization: Where to Begin?

Image optimization is very similar to video SEO. You want to align your signals for the best result, which means you want your URL to correspond with the alt text, which should correspond with the title attribute, which should correspond with the caption (if one is there).

Let’s use real estate for an example. If I were selling a home in Columbia, MO, and had an image of the home, it may look something like the following:

<img src=”columbia-home-for-sale.jpg” alt=”Columbia MO Home for Sale” title=”Three Bedroom Home for Sale”  />

I began by saving the file to my server with an appropriate URL structure (using dashes, not underscores), created alt text descriptive of the image – including keywords like Columbia MO to add more relevance – and finally added a title attribute that brought it all together. Notice how they all have a unified theme, but aren’t duplicated.

When used correctly, alt text contains the ability to provide organic search benefits, which means more exposure for your site, products, posts or even your own byline.

However, don’t go overboard here; just because it’s image search doesn’t mean Google forgets about keyword stuffing or fishy titles. My best advice is to do what is best for the reader. Think of it this way, in the previous example, if the image was of a for sale sign in front of the home, you immediately know what is happening, so tell it that way in the alt text.

Writing Alt TextAlt Key on Gray Keyboard

Alt text should be a natural language description of the image. It shouldn’t ever surpass a single sentence and from personal testing, it is best to keep it under 8-10 words or 120 characters in length, although 5 or 6 words is usually enough.

Take this image of a VA Loan guide: great alt text here would be something like “VA Loan Guide Cover.”

If you are using a popular CMS like WordPress, Drupal or Joomla this is easily inputted; however, if you are coding it in HTML, the format should look like what we had in the above example.

What to Avoid when Writing Alt Text

Alt text could be seen as the cross between a title tag and the anchor text of an html link. This combination leads to some dos and don’ts and the most common don’ts include:

Don’t stuff keywords

<img src=”columbia-missouri-como-mo-65203-home-for-sale.jpg” alt=”Columbia MO, COMO, 65203, Missouri Home for Sale | Residence for Sale | Homes Sales”  />

  • Can you tell I’m trying to get home searches in Columbia to see the house?

Limit the length

<img src=”columbia-home-for-sale.jpg” alt=”Thee bedroom two bathroom home for sale in the Columbia, Missouri area located in the south part of town next to the Break Time gas station that carries Big League Chew”  />

  • This is overkill, and leads in to the next point…

Don’t use alt tags out of context

  • In the previous example, you tell I went way off-base, going beyond what the image was about and into a load of other items that shouldn’t be included.

For additional information, see this video from Matt Cutts on writing great alt text:

  • Denice

    Thanks for putting this in plain language for non-developer types.

    I have a question. My clients – architects and designers, use extensive image galleries on their sites to showcase their completed projects. There may be 12 images of a kitchen renovation, so how different should each image name and alt text be? Would every image have practically the same alt text, such as alt=”Lake Forest kitchen renovation breakfast bar”,
    then the next photo in the gallery would have:
    alt=”Lake Forest kitchen renovation light fixtures”

    I’m still not sure if I understand how the image name and the alt text would be different. In the above example I would think that all 12 images would have the same file name, such as: ABC Kitchen Remodeling Lake Forest. How would I make the 12 image names different from each other without being redundant of the keywords used in the alt text?

  • Matt Polsky

    Sorry about the extreme delay on the response Denice. Duplicating the title and alt may seem like a low priority, but if your client works with many galleries on the same domain, then the duplicated alt tags and titles can actually prevent you from ranking in image search.

    There’s a couple options you have here. 1) find ways the images are different (even if it is very minimal) or 2), and my personal favorite, use semantic terms. Not everyone will search for kitchen renovation, but kitchen upgrade, kitchen remodel, kitchen restoration, galley renovation, etc. Go beyond the head terms and dig into all angles of the image. Not only will these keep things from being duplicate, but you’ll find your images ranking for more terms in image search.

  • Bruno Simon

    How to add Alt Text (as each Image File Name) to 1000 images with Lightroom or other app.? Please advise!