Microsoft and Bethesda confirmed that Starfield will be available for preload on Xbox Series X (and S) first, starting on Thursday, Aug. 17. On Xbox platforms, Starfield weighs in at approximately 125 GB. That’s almost a third of the usable storage space on an Xbox Series S SSD, so you may want to look into a storage expansion card for your Xbox if you’re short on space.
Starfield on PC will be available to preload starting Aug. 30. That version of the game will eat up about 140 GB of storage space, according to the game’s listing on Xbox.com.
Pre-download from today on xbox
I DL'd on my XBox Series X and it was listed at 139GB. 
Had to move a bunch and make some hard choices about what stayed and went lol.
Had to move a bunch and make some hard choices about what stayed and went lol.