Video quality explained: 720p vs 1080p vs 4K
p numbers are vertical pixels: 720, 1080, 1440, 2160 (often called 4K). They are not a promise of sharpness if the original upload was smaller.
What the labels mean
720p is a common HD size for phones. 1080p is Full HD and still the default for most people. 1440p and 2160p (4K) are larger still. Bitrate matters as much as resolution: a poorly encoded 1080p file can look worse than a clean 720p file.
File size and limits
Higher resolutions grow quickly. A few minutes of 4K can exceed a mobile plan or YTSave’s maximum download size. If a job fails for size, pick a lower rung on the list.
You cannot invent 4K
If the uploader published 720p, no downloader can honestly offer 4K. YTSave only lists renditions the source returned. Upscaling in an editor is not the same as downloading a real 4K master.