Mass Effect Legendary Edition will release within seven days of this article going up and players can already check out the download size as well as preload date and time.
Preloads for Mass Effect will kick off on Wednesday, May 12, 2021.
The game will be quite chunky as the PS4 version will require downloading about 80 GB for the US version or over 100 GB for EU version. Xbox file size will be slightly larger, with 83 GB in US, with probably more in EU.
You might be asking yourself why the EU file size is bigger and the reason is probably localisation since the package will include more than just English language. That said, it remains to be seen if we will get the option to not install them in the EU version and only go for English in order to get a smaller download and file size.
Furthermore, it appears that the download will be separated in two packs - the base game and the Day 1 patch, known as update 1.01.
PC version's download size is not known at this point but the Steam store lists 120 GB of free space as one of the requirements. Keep in mind that the store often asks for more disk space than the game actually ends up requiring so it's possible that the PC version is around the same numbers as the console one.