Added an "FAQ" section to that article. How does it look now? https://www.mediawiki.org/wiki/Common_thumbnail_sizes
Cheers, -Travis On Fri, Jan 23, 2026 at 10:38 PM Sam Wilson via Wikitech-l < [email protected]> wrote: > This is great, and I'm sure many 3rd party installs will be glad of it too > (to reduce their thumb storage requirements). > > A couple of times lately I've had the "429 Use thumbnail steps listed on > https://w.wiki/GHai"; message, and because I'm a bit slow on the uptake I > went looking for the steps to follow to get thumbnails. Has anyone else > been confused by this? If it's just me, ignore this, but perhaps we could > update the message to say "Use the values of $wgThumbnailSteps listed on…" > instead. > > > On 24/1/26 02:27, Amir Sarabadani via Wikitech-l wrote: > > Thumbnails shown on-wiki are already quantized to a set of standard sizes > (if a non-standard size is requested, the next-larger standard size is > used, and scaled to the requested size by the browser). We have recently > extended the set of standard sizes, and are now moving to only allow > standard sizes to be used. Regular editing and viewing will not be impacted > by this change at all. > > * What isn't changing? > > Thumbnails served on wiki (via the "thumb" argument to File:, and via the > Media API) will continue to behave as they do now - if you request a > non-standard size, the next-larger standard size will be provided, and > scaled in-browser if appropriate. > > * What is changing? > > Requests for non-standard thumbnail sizes using other methods (e.g. > constructing an upload.wikimedia.org URL with a non-standard thumbnail > size) will be blocked by our CDN. These are already being rate-limited for > requests that we assess are not coming from a web-browser. > > During this quarter, we will be broadening the scope of the existing > rate-limiting and making it increasingly strict, with the aim being to > refuse such requests entirely by the end of March 2026. > > * Why are WMF doing this? > > Historically, we have generated thumbnails of whatever size was requested; > this has been a drain on our thumbnailing infrastructure and cost us in > network bandwidth and storage volume. With the increasing prevalence of > highly aggressive scrapers, this has become an intolerable burden on our > network, infrastructure, and staff, who have spent a lot of time over the > holiday period working hard to keep the wikis available for people to read > in the face of automated abuse. > > * What do I need to do? > > Most likely, nothing: we have already tracked down some of the more > widely-deployed sources of nonstandard thumbnail requests (e.g. Popups > extension) and fixed them. If you own or operate something that requests > thumbnails by constructing a thumbnail URI directly, then now is the time > to either use the Media API instead or to make sure you only request > standard thumbnail sizes. > > * What are the standard thumbnail sizes? > > They are: 20px, 40px, 60px, 120px, 250px, 330px, 500px, 960px, 1280px, > 1920px, 3840px > > They are defined in config as $wgThumbnailSteps - > > https://gerrit.wikimedia.org/r/plugins/gitiles/operations/mediawiki-config/+/refs/heads/master/wmf-config/CommonSettings.php > > And also documented on MetaWiki - > https://www.mediawiki.org/wiki/Common_thumbnail_sizes > > To help fix the existing instances, please see > https://phabricator.wikimedia.org/T414805 for search-links, and examples > of how to fix them. > > Best > -- > *Amir Sarabadani (he/him)* > Staff Database Architect > Wikimedia Foundation <https://wikimediafoundation.org/> > > > > _______________________________________________ > Wikitech-l mailing list -- [email protected] > To unsubscribe send an email to > [email protected]https://lists.wikimedia.org/postorius/lists/wikitech-l.lists.wikimedia.org/ > > _______________________________________________ > Wikitech-l mailing list -- [email protected] > To unsubscribe send an email to [email protected] > https://lists.wikimedia.org/postorius/lists/wikitech-l.lists.wikimedia.org/
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