My internet isn’t really good so I want to know,how much is the (the latest version of) UE4 download size and after downloading it in the launcher how much will its install size be? I will definitely also download some assets and want to know how much bandwidth that will need.So in summary,I want to know UE4 download size with assets and after the decompressing (if there is) install size.Thanks for the help 
I believe the download is about 6GB–at least
You can download it directly which is round about 7gb.
Or you can download the source from GitHub which is about 30mb + 1,5gb dependencies. (You need to have Visual Studio installed).
Here is a video on how to install from GIT - YouTube
4.9 was around 5gb for me.
But for some reason it was 7gb when I downloaded 4.8.