Ecommerce merchants are some of the most demanding customers out there. In a fiercely competitive market, online store owners are constantly looking for ways to deliver a better customer experience and drive sales and revenues. 

One of the quickest ways to please potential customers is to ensure that content loads as quickly as possible. Slow loading content (in particular images) can make the difference between a sale and someone leaving your online store for a competitor. Therefore, the quicker the site loads the more likely a customer is to browse and purchase. One way to achieve a faster loading store is by using a technique called “image compression”

Image compression is the process of minimizing the size (measured in bytes, kilobytes or megabytes) of a graphics file (.jpg, .png, .gif) without changing the physical dimensions or degrading the visual quality of the image to an unacceptable level. This process is often referred to as “image optimization”. If you are new to the concept of image compression you can learn more about it in our sister guide “The Guide to Image Compression”.

The Benefits of Image Compression

Image compression becomes even more important when we consider the growth of the smartphone. Today over half of all ecommerce sales are undertaken on a mobile device.

Depending on the purchaser’s location internet connection speeds will vary. It’s fair to say that not every potential customer will be sat at home with a fast broadband connection and 4k monitor). It’s therefore even more imperative that your images are optimised to ensure they download as quickly as possible.

Thankfully image compression isn’t complicated and thanks to tools like can be set up once and fully automated. It’s now easier than ever to benefit from the speed gains of image compression leaving you time to focus on running your store.

Shopify and Image Compression

If you’re familiar with Shopify you’ll be well aware that you can use a wide variety of image formats with the platform. 

These include:

  • JPEG or JPG
  • Progressive JPEG
  • PNG
  • GIF

It’s possible to upload other formats however Shopify will attempt to convert these into either a JPEG or PNG file format. If Shopify is unable to convert you will receive an error message. Except for these conversions, Shopify doesn’t modify images when uploaded.

After uploading an image Shopify checks the file format and depending on the result runs its own image compression algorithm on it. 

Shopify's image quality levels after compression are:

Between 65 - 90 No change in quality 90

For JPEG/JPG images, the quality level of a compressed image depends on the quality of the original image as well as the output size:

Original quality Output size Output quality
86 or more Height or width of 1024px or more 85
65 - 85 Height or width of 1024px or more Original quality
64 or less Height or width of 1024px or more 65
76 or more Height and width both less than 1024px 75
65 - 75 Height and width both less than 1024px Original quality
64 or less Height and width both less than 1024px 65

As you can see from the table there are certain conditions where compression isn’t applied and others where only minimal compression is achieved. There’s nothing wrong with Shopify’s approach but it does leave some potential gains on the table.

It’s for this reason that we created for Shopify — a dedicated Shopify app that allows merchants to further optimise their images to ensure the quickest download as possible.

The Approach

In “The Guide to Image Compression” we discussed how “Balanced Compression” helps achieve the best file size saving with the best visual image. 

To recap, here’s how “Balanced compression” works in the for Shopify app:

  1. An image is uploaded to Shopify (i.e. a product, collection, theme asset, or blog featured image)
  2. Shopify runs it’s own compression on the original image according to the rules outlined above
  3. If set to automatic compression for Shopify will pick up on the newly added image and will create a series of new images with varying degrees of compression applied
  4. Next, each image is compared to its closest neighbour using a technique called “structural similarity”. If the current image is structurally (i.e. visually) the same to a high degree moves along to see if a better saving can be had with the next image in line.
  5. If a better saving can be had will carry on comparing, if not it sends back the previous image knowing that it’s the best trade-off between visual similarity and file size savings.
  6. replaces the newly compressed image in Shopify 

This approach ensures that delivers the best trade-off between file size and the visual image — after all a highly compressed image that is illegible is rather pointless.

In summary, and to answer our hypothetical question “doesn’t Shopify do this for me already?”, while Shopify does offer a level of image compression better ultimate gains can be achieved using a dedicated image compression app for your store. Better gains equal a quicker image download and a better customer experience.

Automated Compression

The good news for you is that is designed to be “set it and forget it”. Setup takes a few minutes and once configured your Shopify stores images will instantly benefit. Set it to automatic compression and you’ll never have to worry about checking on your images ever again — compression will just happen. also offers another killer feature called “file renaming”. To learn more about the benefits of Image SEO read “The Guide to Image SEO”.


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