Looks great, thanks!
On 25/1/26 12:32, Travis Briggs wrote:
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
<http://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/>
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