MediaWiki extensions manual
Release status: beta
Implementation Media
Description Provides a maintenance script for pre-rendering thumbnails.
Author(s) (Samwilsontalk)
Compatibility policy Master maintains backward compatibility.
License GNU General Public License 2.0 or later

The RenderThumbnails extension provides a maintenance script with which to render thumbnails of uploaded files. This can reduce the load on the web server by making sure the rendered thumbnails are already rendered before being requested, which can be useful in some hosting environments. It is compatible with alternate file backends such as Extension:AWS.

Thumbnails will still be rendered at request time if their sizes are not found, but for common thumbnails such as those on File pages or that are of the default thumb width pre-rendering can be worthwhile.


  • Download and place the file(s) in a directory called RenderThumbnails in your extensions/ folder.
  • Add the following code at the bottom of your LocalSettings.php file:
    wfLoadExtension( 'RenderThumbnails' );
  •   Done – Navigate to Special:Version on your wiki to verify that the extension is successfully installed.



Thumbnail sizes are controlled by various configuration settings, and RenderThumbnail uses these to determine what thumbnails to render.

  • $wgImageLimits — the sizes available on File pages (below the thumbnail), as well as in the "Image size limit on file description pages:" preference.
  • $wgGalleryOptions — the default sizes for gallery thumbnails are set by the imageWidth and imageHeight keys of this array.