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Last updated: 04/09/2026

Regenerate Thumbnails

Regenerate all image thumbnails in your media library. Fix missing or broken thumbnails, generate new custom sizes for existing images, and update metadata.

Overview

Regenerate Thumbnails rebuilds WordPress image metadata and generated sizes across the Media Library when your registered image dimensions change or existing derivatives need to be recreated.

WP PowerSuite processes one image per AJAX request instead of trying to regenerate the entire library inside one long PHP execution. You can see the current registered sizes, start or stop the job, follow progress and activity, and continue past individual images that cannot be processed.

Regenerate Thumbnails is a Free module in WP PowerSuite.

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Who is this for?
  • Sites that changed themes or image-size registrations
  • Agencies rebuilding thumbnails after client redesigns
  • Developers adding custom WordPress image dimensions
  • Administrators recovering missing or outdated image derivatives
  • Sites coordinating image generation with Disable Thumbnail Generation

Features

Regenerate the Entire Image Library
Walk eligible image attachments and rebuild their WordPress metadata and generated sizes.
One Image Per Request
Process attachments incrementally through AJAX to reduce ordinary PHP timeout risk.
Registered Size Overview
See the image sizes WordPress currently expects before starting the regeneration.
Live Progress
Track completed images, current filename, total count, and activity while the job runs.
Stop Control
Stop an active browser-driven regeneration when needed.
Continue Past Failures
Missing files, permission problems, and other per-image failures return a next cursor so the broader job can continue.
Thumbnail Policy Awareness
Respect Disable Thumbnail Generation so suppressed sizes are not recreated during the job.
Safe Re-Run
Starting again walks the library from the beginning, making repeat runs predictable after configuration changes.

Rebuild Thumbnails After Image Size Changes

  • WordPress generates intermediate image files when an attachment is processed. If you later switch themes, register a new image size, change a dimension, or restore media from another environment, older attachments may not contain the derivatives your current design expects.
  • Regenerate Thumbnails walks existing image attachments and asks WordPress to generate fresh attachment metadata using the image sizes that are registered now. This gives older media a chance to catch up to the current configuration without requiring editors to re-upload every image.

Process the Library in Small AJAX Steps

  • Regenerating a large library in one HTTP request is unreliable because PHP execution limits, memory, image-processing time, and hosting restrictions vary widely. A site with thousands of high-resolution images can easily exceed a normal request timeout.
  • WP PowerSuite processes one attachment at a time through AJAX. After an image is handled, the response returns the next attachment cursor and the browser requests the following item. Individual failures can be logged while the cursor still advances, preventing one missing file or permission issue from automatically terminating the entire run.

See the Sizes WordPress Will Generate

  • Before starting, the module reports the number of eligible images and the currently registered image sizes, including their dimensions and crop behavior. This makes the regeneration job easier to understand before it begins.
If you recently created new dimensions with Custom Image Sizes, those registrations are part of the WordPress image-size list and can therefore be produced during regeneration for source images that support them.
After regeneration, Image Sizes Panel can be used on individual attachments to confirm which size URLs WordPress can actually resolve.

Respect Disabled Thumbnail Sizes

Regenerate Thumbnails works through WordPress's normal metadata filters, so Disable Thumbnail Generation still controls which intermediate files are allowed to be created.
If all thumbnails are disabled, the regeneration screen reflects that no generated sizes are active. If only selected sizes are disabled, those sizes are removed from the overview and the underlying generation filter prevents their files from being recreated.
This avoids a common conflict where a regeneration tool blindly recreates files an administrator intentionally disabled elsewhere.

Understand the Browser-Driven Workflow

  • The regeneration job is not a background cron process. The browser needs to remain open while requests continue, and closing the page stops the active sequence. WP PowerSuite warns about closing while the job is running.
  • If you start again later, regeneration begins from the first eligible attachment rather than resuming from a stored mid-library checkpoint. Re-running is safe because WordPress simply rebuilds metadata and current derivatives again, but large libraries should be planned accordingly.

Know What Regeneration Does Not Clean Up

  • Regenerate Thumbnails rebuilds current metadata and sizes. It is not an orphan-file cleaner. Image files belonging to dimensions that are no longer registered may remain in the uploads directory even after a regeneration run.
  • Likewise, the module does not let you choose a single size or arbitrary subset of attachments. Its purpose is a straightforward whole-library rebuild using the current WordPress image-size configuration.

Use Cases

  • Theme Changes
    Rebuild attachment sizes after switching to a theme with different image dimensions.
  • New Custom Sizes
    Generate newly registered dimensions for images that were uploaded before the size existed.
  • Missing Thumbnail Recovery
    Recreate image derivatives after files or attachment metadata were lost or incomplete.
  • Thumbnail Policy Changes
    Regenerate the library after re-enabling previously suppressed image sizes.
  • Agency Redesigns
    Run a controlled library rebuild after changing card, hero, or content-image dimensions.

Frequently Asked Questions

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