Regenerate Thumbnails


Regenerate Thumbnails は画像添付ファイルのサムネイルを再生成します。画像をすでにアップロードした後に「設定 メディア」画面からいずれかのサムネイルサイズを変更した時や、アイキャッチ画像サイズの異なるテーマに切り替えた時などにとても便利です。



  • サムネイルを再生成するプラグイン
  • メディアライブラリーの行にカーソルを置くと、1つの画像のサイズを変更できます
  • チェックボックスと[一括操作]プルダウンを使用して、複数の画像をサイズ変更することができます


  1. 管理画面に移動し、メニューからプラグイン 新規追加を選択してください。
  2. “Regenerate Thumbnails” で検索します。
  3. インストールをクリックします。
  4. 有効化をクリックします。


Installation Instructions
  1. 管理画面に移動し、メニューからプラグイン 新規追加を選択してください。
  2. “Regenerate Thumbnails” で検索します。
  3. インストールをクリックします。
  4. 有効化をクリックします。



Ottimo plugin, molto utile per riaggiornare le immagine nel Template dopo modifiche. +++


It’s amazing how obviously ancient this plugin is if you look at the screenshots, yet it still keeps being updated and it still works great. Nice dedication, thanks for the great plugin.

Always in my design toolkit

When I design custom themes for clients, this plugin is a necessity. Its part of my default ‘install plugins’ pack when I start with a new project. A lot of the times it is necessary to tweak the size of Featured Images, especially testing the responsive side of things.

Useful plugin

After 5 month of usage i can say that it is one of the useful plugin and also i can give my rating as 5 stars.
useful to re generate thumbnails.

Does a decent job of doing what I don’t want to do

I needed a plug-in to regenerate image thumbnails for a client. They have roughly 1,300 images stored and served through AWS/CloudFront. We only needed thumbnails regenerated, but this plug-in is regenerating ALL image sizes, not just thumbnails. As a result, it’s doing 5-10x more work than it should, and it’s timing out without any error messages after the first few hundred. It also failed to generate thumbnails for one of our images and gave reasons as “unknown” – not very helpful. I think it’s because the image is a tif, but that would be pretty easy to return as useful error message, so I’m not sure that’s it.

WordPress refers to its images as “Image Sizes” and specifically the smallest of those is “Thumbnail.” The plug-in should be called “Regenerate Image Sizes” so its name matches what it actually does. Or at least make it clear on the plug-in page that your plug-in is using terminology differently from WordPress to avoid confusion.

I gave this two stars because at least it did perform image resizing, even if it was for a bunch of image sizes it wasn’t meant to resize.



Regenerate Thumbnails はオープンソースソフトウェアです。以下の人々がこのプラグインに貢献しています。


“Regenerate Thumbnails” has been translated into 23 locales. 翻訳者のみなさん、翻訳へのご協力ありがとございます。

“Regenerate Thumbnails” をあなたの言語に翻訳しましょう。

開発に興味がありますか ?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.


Version 2.3.0

Maintenance release. A major rewrite is in the works on GitHub.

  • Add “Regenerate Thumbnails” button to the Edit Media submit metabox. Props Brian Alexander for inspiration.
  • Bump required WordPress version to v3.2 so that we don’t need to bundle jQuery’s progress bar plugin anymore.
  • Context for translators.

Version 2.2.6

  • PHP 7との互換性。

Version 2.2.5

  • プラグイン言語パックサポートに関する更新。

Version 2.2.4

  • Better AJAX response error handling in the JavaScript. This should fix a long-standing bug in this plugin. Props Hew Sutton.

Version 2.2.3

  • Make the capability required to use this plugin filterable so themes and other plugins can change it. Props Jackson Whelan.

Version 2.2.2

  • Don’t check the nonce until we’re sure that the action called was for this plugin. Fixes lots of “Are you sure you want to do this?” error messages.

Version 2.2.1

  • Fix the bottom bulk action dropdown. Thanks Stefan for pointing out the issue!

Version 2.2.0

  • Changes to the Bulk Action functionality were made shortly before the release of WordPress 3.1 which broke the way I implemented the specific multiple image regeneration feature. This version adds to the Bulk Action menu using Javascript as that’s the only way to do it currently.

Version 2.1.3

  • Move the error_reporting() call in the AJAX handler to the beginning so that we’re more sure that no PHP errors are outputted. Some hosts disable usage of set_time_limit() and calling it was causing a PHP warning to be outputted.

Version 2.1.2

  • When regenerating all images, newest images are done first rather than the oldest.
  • Fixed a bug with regeneration error reporting in some browsers. Thanks to pete-sch for reporting the error.
  • Supress PHP errors in the AJAX handler to avoid sending an invalid JSON response. Thanks to pete-sch for reporting the error.
  • Better and more detailed error reporting for when wp_generate_attachment_metadata() fails.

Version 2.1.1

  • Clean up the wording a bit to better match the new features and just be easier to understand.
  • スクリーンショットを更新。

Version 2.1.0


  • Thanks to a lot of jQuery help from Boris Schapira, a failed image regeneration will no longer stop the whole process.
  • The results of each image regeneration is now outputted. You can easily see which images were successfully regenerated and which failed. Was inspired by a concept by Boris.
  • There is now a button on the regeneration page that will allow you to abort resizing images for any reason. Based on code by Boris.
  • You can now regenerate single images from the Media page. The link to do so will show up in the actions list when you hover over the row.
  • You can now bulk regenerate multiple from the Media page. Check the boxes and then select “Regenerate Thumbnails” form the “Bulk Actions” dropdown. WordPress 3.1+ only.
  • The total time that the regeneration process took is now displayed in the final status message.
  • jQuery UI Progressbar version upgraded.

Version 2.0.3

  • Switch out deprecated function call.

Version 2.0.2

  • Directly query the database to only fetch what the plugin needs (the attachment ID). This will reduce the memory required as it’s not storing the whole row for each attachment.

Version 2.0.1

  • I accidentally left a check_admin_referer() (nonce check) commented out.

Version 2.0.0

  • Recoded from scratch. Now uses an AJAX request per attachment to do the resizing. No more PHP maximum execution time errors or anything like that. Also features a pretty progress bar to let the user know how it’s going.

Version 1.1.0

  • WordPress 2.7 updates — code + UI. Thanks to jdub and Patrick F.

Version 1.0.0

  • 最初のリリース。