www.mattkprovideo.com/2024/09/26/youtube-1280-versus-4k/

I have always assumed I should be shooting and editing in 4K (3840 by 2160). I also did my Photoshop and After Effects work in 3840 by 2160.
I did this even for projects that I knew were only going to YouTube/Vimeo/Facebook video.

I recently had to do some projects that the client shot themselves on 1280 by 720.. I upscaled it to 4k and added lots of B Roll and graphics ( that were made at 4K dimensions) over the video.
When watched the finished projects on YouTube a few weeks later, the 1280 by 720 parts looked terribly stretched out.

This is the episode that started off in 1280 but bumped up to 4K, with 4K B roll:
https://www.youtube.com/watch?v=LGERTmLA8ss&t=2617s

But I also knew that when I download stock shots off of YouTube, they are in 1280 by 720. Even scaled up to 4K the footage looked… ok. Not great but just OK.

When I download old shots off my OWN YouTube channel, footage I created myself in 4k and uploaded in 4K (but somehow lost it) they are in 1280 by 720.

Does YouTube turn all footage uploaded to it, even 4K footage into 1280 by 720?

As an experiment, for one of the projects I was crafting from the 1280 by 720 footage, I kept everything in its original 1280 by 720 dimensions, The motion graphics and B Roll, that were created in true 4k? I downscaled them to 1280 by 720. I exported them as 1280 by 720 to YouTube.
The export and uploading times were much faster than 4K projects.

THIS is the show edited and exported in 1280 by 720:

https://www.youtube.com/watch?v=W9sk5pbuVJ4

When I looked at this project on YouTube a week after uploading and it looked fine. No signifigant difference in picture quality.

And I don’t mean just watching it on my phone or laptop. I watched it in the YouTube app on my 4k big screen TV. And it looked the same as my 4K projects. The projects that had 1280 by 720 footage stretched up to 4K looked bad, but the episode that was kept in 1280 looked ok.

Am I wasting my time rendering projects in my full 4K, if YouTube is just going to scale it down to 1280?