Regenerate Thumbnails
by Alex Mills
Rebuilds all image sizes after a theme change so pages stop serving oversized or missing crops.
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What Regenerate Thumbnails does
Rebuilds all image sizes after a theme change so pages stop serving oversized or missing crops.
It sits in the images part of a WordPress stack and is sold by Alex Mills on a free basis. We recommend it in our images guides because it does that one job well without asking you to rebuild the rest of the site around it.
Every plugin adds work to a page request, so treat this as a decision with a cost. Record a speed test before you install it and run the same test afterwards, on the same page, so you know exactly what it charged you.
Real user ratings
Score
4.6/5
Reviews
395
Active installs
1,000,000+
Downloads
22.8M
Latest version
3.1.6
Last updated
2025-08-20
These figures come straight from the public WordPress.org plugin directory API for version 3.1.6, not from us. Check them yourself on the WordPress.org listing. Our own editorial score is 4.6/5.
Where Regenerate Thumbnails ranks elsewhere
Regenerate Thumbnails does not appear in the published "best of" lists we track from WPBeginner, TechRadar, Kinsta, Themeisle and similar sites. That is not a mark against it - those roundups are short and skew towards the biggest names.
What changed in the latest version
- Fix: Respect "Skip regenerating existing correctly sized thumbnails" setting.
- Fix: Don't delete all thumbnails when deleting old unregistered thumbnails size.
- Fix: Don't overwrite 'All X Attachment' button label with featured images count.
- Tested successfully with PHP 8.1.
- Tested successfully with PHP 8.2.
- Fix: Don't attempt to regenerate SVG's.
- Bump tested version.
- Update dependencies.
Release notes are the developer's own words, published on WordPress.org. Read the full changelog
Pros and cons
- Fixes broken image sizes after any theme switch
- Free with no licence to renew
- Actively maintained and used on production sites we test
- Bulk runs are heavy, so schedule them off-peak
- Support is community-led rather than guaranteed
How to use it
- 1Back up the media library, or confirm the plugin keeps restorable originals.
- 2Set a sensible compression level and a maximum image width.
- 3Enable WebP or AVIF delivery and check a page in a real browser.
- 4Run bulk optimisation outside your busiest traffic hours.
- 5Re-test the heaviest page to confirm the weight reduction.
How it compares
Other images plugins we recommend, with their rating and pricing model.
| Plugin | Our rating | WordPress.org | Pricing | Best for |
|---|---|---|---|---|
| Regenerate Thumbnails | 4.6 | 4.6 (395) | Free | Fixes broken image sizes after any theme switch |
| EWWW Image Optimizer | 4.5 | 4.8 (1,839) | Freemium | Unlimited local compression at no cost |
| Imagify | 4.6 | 4.3 (1,653) | Freemium | Simple three-level compression choice |
| ShortPixel | 4.7 | 4.5 (819) | Freemium | Compression happens off your server |
Alternatives
Other images plugins
EWWW Image Optimizer
Exactly WWW
Compresses images locally on your own server or through its cloud service, with no per-image credit counting in local mode.
1,839 reviews · 49.8M downloads · v8.7.7
Imagify
WP Media
Image optimisation from the WP Rocket team, with three compression levels and automatic next-gen format delivery.
1,653 reviews · 21.0M downloads · v2.3.4
ShortPixel
ShortPixel
Remote image compression with WebP and AVIF delivery that keeps a restorable copy of every original file.
819 reviews · 19.9M downloads · v6.5.6