How To Optimise Images For SEO

How To Optimise Images For SEO

Image optimisation is one of the most underused strategies in SEO. Images make your content more accessible, attractive and engaging to users. If you optimise images for SEO, your images to display more prominently in image SERP results can help your website pull in more traffic - and thus potentially increase your leads.

There are many areas of image optimisation that need to be actioned to ensure you correctly optimise images for SEO, below we look at the image SEO best practices that need to be considered when uploading new images onto your website.

Choose the right image

The first consideration in image optimisation is the actual image itself. You will need to choose a relevant, and ideally, unique image to be used on the page or blog post. Stock images are fine to use, however, if other websites have used them before, you may find getting it to rank highly in image results difficult.

When choosing the image to use, it is important to potential copyright infringements, as you dont want to find yourself in the middle of a lawsuit for using a copyrighted image!

Choose the right image file name for SEO

Image optimisation starts with the image’s file name. You’ll want to make it as easy for Google to know what the image is about without even looking at it, so naming image files for seo using your focus keyphrase in the image file name can let you tell them what it is from the file name.

Choose the right format

Depending on the image and how you want to use it, there are different file formats that should be considered.

  • JPEG for larger photos or illustrations as the colours and clarity will be kept in smaller files.
  • PNG for background and large images - if you want to preserve background transparency in your image
  • SVG for logos and icons as they can be resized without any loss of image quality

Image sizing

Ensuring that you use the correct image size is vital as it helps with the page load times and thus the overall user experience of your website. If you upload a 1500x750 pixel-sized image but display it as a 150x75 pixel image on your website, the larger image will be loaded needlessly - slowing your load speed of the page.

Use responsive images

Depending on how your website is built, you may need to ensure that your images are responsive so that they load correctly on mobile and desktop devices alike. If you are using the WordPress CMS, this is done automatically for you, however, if you are not, you will need to add the ‘srcset’ attribute to your image’s CSS code.

File Sizes

To ensure that you optimise images for SEO correctly, we would recommend that you look at your file sizes. There are 2 options for this, firstly you can upload the image in the correct size and thus a much smaller file image or you can use a compression tool.

There are many compression tool options for image optimisation, including WPSmush, ImageOptim, Gimp or Squoosh. You can set these to run audits periodically to ensure that all your images - new and old - are compressed at all times, helping with load speeds.

When the images have been uploaded onto your site, there are more SEO image best practice actions to complete to ensure that your image optimisation for SEO is complete…

Image ALT Tags

The image alt tags (or ALT text) is added to an image so there will be descriptive text in place if the image can’t be displayed to the visitor for any reason. The image ALT text is also there to enhance your website’s accessibility as it helps the visually impaired - and is an excellent opportunity to utilise ALT tags for SEO by adding the keyphrase for that page if it’s appropriate to do so.


The image caption is the text that usually accompanies the image on the page in a box underneath the images. According to Kissmetrics in a 2012 survey, captions are read on average 300% more than the body copy itself, so this is a vital opportunity that needs to be used to hook in potential readers.

This is a caption.

Title Text

Title text appears when your mouse hovers over the image. Most people will simply copy the ALT tag to use as this title text, which is fine to do, however, we would recommend using a unique description of the image for the title.

Utilise image-structured data

Adding structured data to your images and pages will help Google (and other search engines) display your images as rich results. While Google says structured data doesn’t help with rankings, it does help to achieve a more ’complete’ listing in image searches as well as helping you stand out and improve your CTR%.

XML image sitemaps

Google themselves say it is a good idea to “use Google image extensions for sitemaps to give Google more information about the images available on your pages. Image sitemap information helps Google discover images that we might not otherwise find”, so with this in mind, it would be foolish to exclude your image files from sitemaps.


As you can see, there are many actions to take to ensure that your images are optimised on your website. Keep the 10 things below in mind when adding an image to an article and you should find your images helping your overall SERPs performance

  • Use relevant images for your page copy
  • Pick a good, relevant, file name for your image
  • Make sure you upload an image with the image dimensions that match the size displayed
  • Use ‘srcset’ if necessary
  • Reduce file size for faster loading
  • Add a caption, using keywords if appropriate
  • Use image alt tags
  • Add structured data to your images
  • Add images in your XML sitemaps
  • Provide all the context you can to help not only Google but also your website users

How Can Bidmark Help You

Our image optimisation service team in Leeds can help you understand how your images are currently performing and how you can further optimise images for SEO to ensure optimum performance. Contact us to discuss how our image optimisation service could help you conquer your targeted search results.


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