13 March 2020
Google has rolled out some new features and updates for Stadia and the most notable one is the ability to stream in 4K on the Chrome on the web. Up until now, the 4K visuals were available with the Chromecast Ultra and televisions only and now the addition to the web is a welcome change.
A Community Manager on the subreddit announced the availability and the requirements to have the best experience on the web. The main and the obvious requirement is a monitor with 4K resolution. Others include a GPU capable of decoding VP9 in hardware, selecting “Best visual quality” in Data Saver settings within the Stadia mobile app and an internet connection of 35Mbps or higher. However, 9to5Google noticed that 4K visuals can still be experienced in “good” connections too. So, the attaining the "best" or the mentioned Mbps speed may not be the hurdle for you to stream the Stadia on the web.
When enabled you will see the 4K icon visible under Connection setting.
Note that if you don’t have a 4K monitor then you won’t see Stadia pushing it further. It’s possible that your account receives the upgrade but having no capable device to churn its potential is a total waste.
According to Google’s support page for Stadia, the 4K streaming uses 20GB per hour (on TVs with Chromecast Ultra). You can also test your connection by going to the speed test page provided by Google for its Stadia.