Windows Central published a story that the Xbox Series X internal SSD has 802GB of usable storage.

Xbox Series X internal SSD has 802GB of usable storage

Xbox Series X packs 802GB of usable storage, while the 1TB expansion card features 920GB. What you need to know Xbox Series X launches with 802GB of usable storage, reports IGN. While the Xbox Series X launches with custom 1TB internal NVMe SSD, the operating system (OS) and system files occupy a portion of the drive. The Seagate Storage Expansion Card for Xbox provides an opportunity to upgrade your onboard SSD storage, available for preorder at $220 in the U.S. Microsoft launches the Xbox Series X console this November, and with devices now in the hands of select media outlets, we're gaining a clearer understanding of its launch offering. For both Xbox Series X and its affordable counterpart, Xbox Series S, some of the primary gains come from a custom NVMe solid-state drive (SSD) bolstering storage with faster speeds. 

Xbox Series X internal SSD has 802GB of usable storage