How should I best optimize images on my website for SEO?

Not only do images make your website more visually appealing but they also have an impact on SEO. For this reason it’s important to ensure you’re optimizing images as part of your SEO activities. In this article we’ll cover the key requirements to ensure images are best optimized for SEO.

Use unique images not found on other websites

Google likes websites that have unique original content. Whenever possible you should avoid using stock images that can often be found on 100s of other websites and instead opt for unique imagery. If you must use a stock image you won’t get the same SEO benefits but you should still optimize with the other tips contained in this article.

Use the correct image file format

There are a number of different file formats for images used on the web:

  • WEBP – modern format designed for the web, best format to use if possible.
  • GIF – good for simple images (not photos) when transparency isn’t required.
  • JPG – good for photos but doesn’t support transparency.
  • PNG – best format for when transparency is required.

Using the correct file format allows you to compress images to the smallest file size possible.

Optimise the image file size

When it comes to optimizing the file size of an image you first need to ensure that the image dimensions aren’t larger than they need to be. For example if you have a featured image on a blog post that will never need to be displayed wider than 960 pixels resize the image width to be that size.

With the image at the correct dimensions you also need apply some compression. You can upload images to be compressed to one of the many free online tools like this one. Alternatively most image editing software will have an option that allows you to tinker with the compressions levels before saving.

Use descriptive file names

When saving an image you should use a descriptive file name. For example if you had an image of a blueberry cupcake you should use a descriptive filename like freshly-baked-blueberry-cupcake.jpg.

Provide descriptive alt text

Alt text stands for alternative text. It’s displayed in the browser if for some reason an image can’t be rendered. It’s also important for accessibility as it helps visually impaired users understand the content of an image. Good alt text should describe the image as best possible, for example:

<img src="/images/white-candle.jpg" alt="Small white candle burning on a shelf" />

Most popular content management systems will allow you to input your desired alt text and then output that text into the HTML of your website.


Before adding images to a website it’s important to follow the tips provided here. It’s also strongly recommended that existing images on a website are also optimised inline with these tips to ensure your website is as SEO friendly as possible.