How to Optimize Website Images for SEO : 12 Image SEO Tips

Website content and blog posts need images to make them more descriptive and engaging to users. Images help to illustrate content, break up blocks of text, and provide a better user experience. Image SEO ensures that images are properly optimized to improve SEO performance.

Images also help to increase traffic to your website from Image search, and help to make your website more accessible to people using screen readers.

However, images have a large impact on site speed and can negatively impact SEO rankings if they are not optimized. All website images need to be optimized for SEO to ensure that they do not slow down the page load speed.

This post discusses 12 best practices to optimize images for SEO.

What is Image SEO?

Image SEO is the process of optimizing images so that they are easy to read and understand by search engines. This is achieved by optimizing the image file size, alt text, load time and more. Image SEO helps to improve the search rankings and visibility of your content on the search engines.

Why is Image SEO important?

Site speed is a critical part of image SEO. In 2021, Google introduced the Page Experience Update which made website page speed a search ranking factor on both desktop and mobile. Sites have to load fast for good SEO rankings.

If images are loaded on a website without optimization, they can be very large and load slowly. This can slow down the page load speed and cause the SEO rankings of your website to be negatively impacted.

A slow loading website will also cause people to abandon the site before it loads. This increases the website bounce rate and decreases the traffic, click-through rate and conversions.

53% of visits are abandoned if a mobile site takes longer than 3 seconds to load. (Google)

Image SEO also helps to make a website more accessible. This helps people who are using screen readers to read the website.

Image search is becoming more important on Google. Image search helps people visually search for information on the web. Proper optimization of images ensures that they rank well and can be easily found when people search on Google with relevant keywords. This results in more targeted website traffic.

Images are returned for 22.4% of searches on Google. (Moz)

For certain keywords, Google shows image packs with direct links to the websites from where the images are taken as shown in the figure.

Image packs in Google image search

Image packs in Google image search

New AI-based image technologies have been announced by Google such as MUM (Multitask Unified Model) which allows users to search visually and is coming soon. Google Lens is available now and enables you to search online with an image or your camera.

12 Optimization tips for Image SEO

1. Select the right image formats

Most of the images that are used on websites are in JPEG or PNG format.

  • The JPEG format is good for photographs and most website images. JPEG images use a lossy format. You can adjust the image quality with a compression tool to reduce the file size and the image will still look good.
  • PNG is good for images like logos where you want to preserve the transparency of the image background. It uses a lossless image format. PNG images will have a large file size.

Google images also supports additional image formats including GIF, SVG and WebP.

2. Compress all images to reduce file size

Image file sizes are a very important factor for SEO. Images can directly impact page load speed and make web pages slow to load. This negatively impacts the SEO rankings and performance of the web page.

Most website issues with slow page speed are caused by large images. Uploading large images without compression can result in very large files that will slow down page speed and negatively impact SEO. Plus, no one will wait around for the images to load.

A fast page load speed is very important for mobile users who may be accessing the website on a slow connection.

To ensure that images do not slow down the page speed of your website,

  • We recommend compressing all images to be less than 100k in file size before loading them on your website.
  • Use image compression tools like Photoshop to compress the image before it is loaded on the website.
  • Once you upload your compressed images, test the website page speed using Google’s Page Speed Insights or GTMetrix.

Read our article on Speed Matters: 5 Reasons Why Web Page Speed Impacts SEO Rankings for more information.

3. Use descriptive image file names

Image file names are important for SEO. Search engines scan the image file names to determine the subject matter of the image.

  • File names should be specific and describe the image. E.g. cute-puppies.jpg instead of the generic IMG_0650.jpeg
  • Use relevant keywords in your image file names if they apply to the image.
  • Use hyphens to separate the words in your file name.

4. Use descriptive Alt Text

Alt text describes the contents of the image. This is one of the most important meta tags for image SEO that has many SEO benefits.

Google uses the alt text along with the page content to determine what the image is about when indexing the image. Alt tags can also be used as anchor text if the image is used as a link.

Alt tags are also important for accessibility. They are used by visually impaired users who are using screen readers.

Alt tags also describe the image in cases where users have image display turned off or are on low bandwidth connections.

Example of Image Alt text for Image SEO

Example of Image Alt Text

  • Use short, descriptive text in the alt tags to describe the image. Eg. “Cute puppies playing in the park”. Do not leave it blank.
  • Use relevant keywords in the alt text if they apply to the image.
  • Do not keyword stuff your alt text.

If you have a WordPress site, it is easy to fill in the alternative text, titles and captions for the image when you upload the image into the media library. No coding knowledge is required.

Image Alt tags and title markup on WordPress media library

Image Alt tags markup in WordPress sites

5. Use Responsive images

Most online users now use mobile devices to search the web. All website images must be responsive and mobile friendly. Responsive images ensure that visitors are shown images of the right size for their device screens whether they are on computers or mobile devices.

Websites use the img srcset attribute to specify several images of different sizes for the browser to select from, depending on the size of the visitor’s screen size.

Image Srcset code example for responsive images in image SEO

Image Srcset code example for responsive images

6. Load images in the right dimensions

Images should be uploaded in the right dimensions to be shown on the website. If the image to be shown on the page is 600px by 400px, upload the image in those dimensions.

Uploading a larger image which will have to be fully loaded and resized before it is shown on the page will slow down the page speed.

Also the width and height dimensions of all images have to be defined before they are loaded. This prevents CLS (cumulative layout shift) which is caused by images shifting around while the page is loading.

Image elements should have explicit width and height to reduce layout shifts - recommendation from Page Speed Insights

Image dimensions recommendation from Page Speed Insights

7. Use image captions & titles

Image captions and titles do not directly affect SEO rankings. However, since the captions are visible under the image, they help to describe the image to the reader and improve the user experience.

8. Use high-quality unique images

The images on your website should be high-quality, unique and original to provide a good user experience to visitors.

Use pictures that you have taken. Avoid using generic stock photos that are used on hundreds of sites.

9. Image placement & surrounding text

Place the most important image at the top of the web page or blog post.

The content of the web page must complement the image. Images must be placed near text that is relevant to the image. Search engines will scan the page content to understand the subject matter of the image.

10. Use Lazy Loading for images

Use lazy loading for images on your website. Lazy loading helps to speed up page load time by deferring the loading of images that are not visible or “below the fold” until the user scrolls near the images. Only the images that are visible are loaded.

Lazy loading helps to improve page speed on long pages which have lots of images below the fold.

Consider lazy loading offscreen and hidden images to lower time to interactive - recommendation from Google Page Speed Insights

Lazy-loading images recommendation from Page Speed Insights

11. Use Structured Data

Use structured data markup for images. Search engine spiders like Google read the structured data to understand the images and the content of the page for search indexing.

Structured data markup uses markup. You may need the help of a developer to implement this.

When you use structured data, your image may be displayed as rich results with a badge which can increase targeted customers to your website.

Google supports structured data markup for:
• Product
• Videos
• Recipes

Image SEO: Example of Rich Results in Google search

Example of Rich Results in Google search

12. Use Image Site Maps

If you have a lot of images on your site, you can use a separate image site map, in addition to your regular XML site map for your website.

Image sitemaps allow you to add URLs from other domains such as images that are hosted on a Content Delivery Network (CDN).

Adding images to a sitemap helps Google discover images that they may not have found otherwise.
Here is more information on Google image site maps.


Image SEO is very important to improve SEO rankings and website performance. All images need to be optimized for SEO before they are loaded on your website to reduce the file size and loading speed.

By following these 12 image SEO best practices to optimize your images before you add them to your website, you can ensure that your website images will help to improve your SEO visibility and performance.

Related Articles

  1. What is SEO and Why is it Important?
  2. What is Local SEO? Why is Local Search Important?
  3. What is On-Page SEO? Plus SEO Best Practices.
  4. Gold Mango Design, 10 Local SEO Tips to Boost Local Search Rankings
  5. Speed Matters: 5 Reasons Why Web Page Speed Impacts SEO Rankings

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