If you have ever run a Google PageSpeed test on your Shopify store, you have likely seen the warning: "Serve images in next-gen formats" or "Efficiently encode images."
High-resolution product photography is essential for selling, but it is also the number one reason Shopify stores load slowly. A slow store means lower rankings on Google and, more importantly, lost sales from mobile customers who won't wait for a page to load.
The solution is image compression. But manually resizing thousands of product photos is impossible for a busy merchant. In this guide, we will look at how to enable automatic image compression so every new product you upload is optimized instantly in the background.
Why You Cannot Rely on Shopify's Default Settings
Many merchants assume Shopify handles this automatically. While Shopify does generate different image sizes for thumbnails, it does not always aggressively compress the file size for bandwidth optimization.
Without a dedicated compression engine, you are often serving files that are 2x or 3x larger than they need to be, without any noticeable difference in visual quality. To fix this, you need a "set and forget" automation tool.
Step 1: Choose an Automation App
To automate this workflow, you need an app that hooks into Shopify's "file upload" events. There are several options on the market, but for this tutorial, we will use Auto Media Optimizer because it focuses specifically on background automation without complex configurations.
Install link: https://apps.shopify.com/auto-media-optimizer
Step 2: Install and Sync Your Library
Once you have installed the app from the Shopify App Store, the first step is usually a "Sync" or "Scan."
The app will look through your Products, Collections, and Files API to build a list of unoptimized assets. Do not worry—this doesn't change anything on your live site yet; it just calculates how much space you can save.
Step 3: Enable "Auto-Optimize" Mode
This is the most critical step for automation. Look for the setting labeled "Automatic Optimization" or "Autopilot."
When you turn this on, the app creates a background listener. Here is what happens next:
- You upload a new product photo to Shopify.
- The app detects the new image instantly.
- It compresses the image according to your settings (we recommend "75-80" for the best mix of quality and speed).
- The optimized version replaces the heavy original automatically.
You no longer need to use Photoshop or online compressors before uploading. You just upload, and the app handles the rest.
Step 4: Bulk Optimize Existing Images
Enabling automation handles future images, but what about the thousands of images already on your store?
Navigate to the Dashboard and click "Optimize All" or "Start Bulk Task." This process runs in the cloud, so you can close the window and turn off your computer. The app will work through your catalog image by image.
Note: We always recommend backing up your theme or ensuring the app has a "Restore" function before running a bulk action, just in case you prefer the original version.
Step 5: Check Your New Speed Score
After the optimization is complete (it might take a few hours depending on your store size), head back to Google PageSpeed Insights.
You should see a significant drop in "Total Page Size" and a faster "Largest Contentful Paint (LCP)" score. Faster loading times directly correlate to better ad performance and higher conversion rates.
Conclusion
Speed is a competitive advantage in 2025. By automating your image compression, you remove a tedious manual task from your to-do list and ensure your store is always fast, no matter how many products you add.
Ready to speed up your store? Try Auto Media Optimizer for free on the Shopify App Store.