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Understanding Smush Image Resizing: Why Some Images Don't Resize and How to Fix It

21 threads Sep 9, 2025 Plugin → Smush image optimization – optimize images | compress & lazy load images | convert webp & avif | image cdn

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Many WordPress users rely on the Smush Image Optimization plugin to automatically resize their uploaded images to more manageable dimensions. However, a common point of confusion arises when certain images are successfully resized while others, seemingly at random, are not. This article explains the most likely causes for this behavior and provides steps to resolve it.

Why Doesn't Smush Resize All of My Images?

Based on community support threads, the Smush plugin's resize functionality has specific parameters that determine when it will process an image. The most frequent reasons an image might not be resized are:

  • File Size Limits: The free version of Smush has a file size limit for optimization. If an image exceeds 5MB, the plugin will not be able to process it, which includes resizing.
  • Resize Threshold: The 'Resize my full size images' option is designed to only shrink images that are larger than the dimensions you specify. For example, if you set a maximum size of 2048x2048, an image that is 2000x2000 will be ignored, while a 4000x4000 image will be resized down.
  • Image Already Processed: If an image was already optimized or resized by Smush during a previous upload or bulk smush, it will not be processed again unless you use the 'Re-check images' button in the Bulk Smush area.
  • Conflicts with Other Code: Custom code snippets, like the add_filter('jpeg_quality', function($arg){return 100;}); filter mentioned in a support thread, can sometimes interfere with how WordPress handles images before Smush can process them.

Troubleshooting Steps: Getting All Your Images to Resize

If you find that Smush is not resizing some of your images, follow this troubleshooting guide.

  1. Check the Image's Original Size: Before uploading, verify the file size and dimensions of the problematic image. Ensure it is under the 5MB limit for the free version and is indeed larger than the maximum dimensions you have configured in Smush > Bulk Smush > Resize my full size images.
  2. Review Your Resize Settings: Double-check the settings you have entered. The plugin will only resize an image if its width or height exceeds your set values. It maintains the aspect ratio, so the final image might have one dimension at your maximum value and the other slightly smaller.
  3. Run a Manual Bulk Smush: Navigate to Smush > Bulk Smush and click 'BULK SMUSH NOW'. This process will attempt to optimize and resize all images that meet the criteria and haven't been processed before.
  4. Check for Plugin or Theme Conflicts: A common cause of unexpected behavior is a conflict with another plugin or your theme. To test for this, temporarily deactivate all other plugins and switch to a default WordPress theme (like Twenty Twenty-Four). Then, upload a new test image that should be resized. If it works, reactivate your plugins one by one to identify the culprit.
  5. Inspect Custom Code: If you have added custom PHP code to your theme's functions.php file to adjust image quality or handling, try temporarily removing it to see if it resolves the resizing issue.

Important Notes on What Smush Resizing Can and Cannot Do

  • No Cropping: It is crucial to understand that Smush resizes images but does not crop them. Resizing scales the entire image down proportionally. Cropping involves cutting away parts of the image to change its aspect ratio, which is a function of the WordPress core media editor or other dedicated plugins.
  • Original Images Only: The resize feature typically only affects the original, full-size image uploaded to the media library. The various thumbnail sizes generated by WordPress are optimized for compression but are not individually resized by this specific Smush setting.
  • DPI is Unchanged: Smush does not alter the DPI (dots per inch) resolution of an image. A 300 DPI image will remain 300 DPI after being resized. This metadata has no bearing on web display but can be important for print. Adjusting DPI must be done manually in an image editor before upload.

By understanding these parameters and following the troubleshooting steps, you should be able to resolve most issues related to images not being automatically resized by the Smush plugin.

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