Regenerate Thumbnails Review: Fix Broken Image Sizes in WordPress (2026)
What Is It?
Rebuilds all image sizes in Media Library after theme changes or custom size additions. 1M+ installs, 4.6/5 stars (395 reviews). By Alex Mills / Automattic.
When You Need It
- Switched themes — images stretched/cropped wrong
- Added custom image size — existing uploads missing it
- Changed thumbnail dimensions in Settings
- Images look distorted in post grids
Key Features
- Bulk regeneration with progress bar
- Single image regeneration
- WP-CLI support (
wp media regenerate) - Skip existing option
- REST API based — no timeouts
Free vs Premium
100% free. Maintained by Automattic.
Pros and Cons
Pros: Does one thing perfectly, Automattic maintained, WP-CLI, safe to deactivate after use
Cons: Does not delete old sizes, slow on 5K+ images without CLI, infrequent updates
Who Should Use It?
Anyone with broken image sizes after a theme change. Install, run, deactivate. It is a maintenance tool, not permanent.
Best Alternatives
- Force Regenerate Thumbnails — Also deletes old unused sizes (saves disk space)
- WP-CLI —
wp media regenerate --yes, no plugin needed, fastest
FAQ
Deactivate after?
Yes — recommended. Run-once tool.
Deletes originals?
No — only regenerates additional sizes.
How long?
500 images: 5-10 min. 5K images: use WP-CLI (5-10 min vs 30-60).
Saves disk space?
No — use Force Regenerate Thumbnails for cleanup.
Sources: WordPress.org, Alex Mills
Written by Marvin
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