Image SEO: How to Optimize Images

Image SEO: How to Optimize Images

In this article, we are going to cover how you can optimize images for SEO.

Image SEO

Google has its own guide for this, Google Image best practices, in which they state:

“By adding more context around images, results can become much more useful, which can lead to higher quality traffic to your site. You can aid in the discovery process by making sure that your images and your site are optimized for Google Images.”

There are a number of things that you can do to your images to optimize them for SEO. For the purpose of 5 Min SEO, we are going to break these down into different steps. We will cover:

1 – Alt Text

2 – File Names

3 – File Type

4 – Image File Size

5 – Image Sitemap

1 – Optimize Image Alt Text

If you are following along with the emails, we are going to start here. 

What is Alt Text?

Alt text is used to describe what is in an image. From Google, “The “alt” attribute allows you to specify alternative text for the image if it cannot be displayed for some reason.”

Why is Alt Text important?

The most practical use of alt text, and why you should genuinely try to do this well, is for helping the visually impaired. If someone has trouble seeing, or cannot see at all, they can use a screen reader which will read to them what is on the page. When the screen reader comes to an image, it will read the alt text to describe the image.

Secondarily, alt text can help improve your SEO by:

  • Increasing the relevance of your web page, by including content related to your topic
  • Acting as anchor text if the image is used as a link
  • Helping your image to rank for specific keywords in Google Images

Best Practices for Alt Text

  • Alt text should be short and descriptive. 
  • You want it to describe the image (remember the visually impaired when you are writing your alt text)
  • Try to include your keyword in your alt text, but don’t go overboard or force it

How do you add Alt Text to an image?

This will depend on what CMS (content management system) you are using (WordPress, Squarespace, Shopify, etc…).

In WordPress, when you add an image, there is a field in the image settings where you can enter the alt text:

Adding alt text to an image

Here is a guide to adding alt text in Squarespace

Here is a guide to adding alt text in Shopify

Additional Resources for Alt Text

Ahrefs has a great guide on image Alt Text.

For a deeper dive into accessibility issues, you can check out WebAIM’s page on alt text

2 – Optimize Image File Names

If you are following along with the emails, this is the second day of Image SEO.

Image file names are another aspect of images that can be optimized for SEO. 

From Google, “Likewise, the filename can give Google clues about the subject matter of the image. For example, my-new-black-kitten.jpg is better than IMG00023.JPG.”

You will want to go through each of your images and update their file names to something that is short and descriptive. Similar to alt text, if you are naturally able to include a keyword, go for it, but don’t force it and over-optimize.

How do I change my image file name?

WordPress – There is currently, no native way to change a file name in WordPress. So, you have two options:

1 – You can download the image, rename it on your computer, and then reupload it to your WordPress site.

2 – You can use a plug-in like Phoenix Media Rename which will allow you to rename your media files from within WordPress.

Squarespace – Squarespace allows you to rename media from within their platform. Here is there guide on how to do that.

3 – Optimize Image File Types

There are 3 main types of image files: JPEG, PNG, and GIFs. The main considerations between these come down to file size and image quality.  A small file size helps your web page to load faster, which helps SEO, but a smaller file size also means a lower quality image. This is a balancing act that you have to determine as a site owner.


JPEG images will have the smallest file size, but also the lowest quality. They are best used for actual photographs, as typically, there is not a large noticeable difference in image quality.


PNG images will be the largest file type and are best for images with text and lines in them.  Here is a good illustration from on why in some cases you would want to use PNG files, even though they are larger:


GIFs are best for moving images. If you want to waste time and browse through more GIFs that you can image, head over here.


There is a new image file type, WebP, that is essentially better than both JPEG and PNG, but there are not as many tools out there that easily convert or create WebP images at this point and so it is good to be aware of, but unless you want to dive fully into learning this, for now, it is easier to stick with PNG and JPEG.

How do I change image file types?

There are a number of tools that allow you to change your image file types and which one you use will depend upon your operating system and what tools you already have installed. This is something that you will need to do on your computer and then re-upload to your website.

Here are some ways to change your image file types:

4 – Reduce Image File Size

Reducing the file size of your images helps your site to load faster, which helps improve your SEO. Smaller files take less time to load than larger ones and so you want to optimize the size of your images.

From Google: “Images are often the largest contributor to overall page size, which can make pages slow and expensive to load.”

Google also has a pretty technical guide on image optimization if you are interested in diving deep into image SEO.

How to reduce the file size of your images 

You will want to use a plugin or tool to do this. If you have a WordPress site, it will be easier and quicker for you to use a plugin (there are a few we recommend in just a second).  If you don’t have a WordPress site, here are some of the best options:

  • ImageOptim – An online tool that allows you to upload images and then it will automatically resize them for you (There is also a downloadable Mac version).
  • ShortPixel – Another online image optimization tool.
  • TinyPNG – Another online image optimization tool.

If you use one of these options, you would want to first optimize the image and then upload it to your website.

WordPress Image Optimization Plugins

If you already have a bunch of pictures up on your WordPress site and you don’t want to find them, resize them, and then upload them again, you can use a plugin that optimizes images on your site. Here are three of the most popular ones:

For these plugins, typically, once you install them, you can go to their settings page and optimize current images, as well as, setting them up to optimize any new images that you upload.

5 – Create an Image Sitemap

From Google: “Images are an important source of information about the content on your site. You can give Google additional details about your images, and provide the URL of images we might not have otherwise discovered by adding information to an image sitemap.”

If you are using an SEO plugin like Yoast or RankMath to create a sitemap, then they should automatically include images in your site map. You can always check the settings for this. Here is what it looks like in RankMath:

Images included in sitemap settings for Rank Math

Likewise, Squarespace also includes images in their sitemaps.

If you are using a different platform or plugin, go and make sure that your images are being included in your site map or you may have a separate sitemap specifically for images, either works fine.

If images are included, you are good to go. If not, check their documentation or head over to the Facebook group and we can try and help out.

Additional Resources

This is all we are going to cover in this guide, but if you would like to dive further into image SEO, here are some great resources:

As always, head over to the 5 Min SEO Facebook Group and post any questions you have there.

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