The Galaxy S5 ROM uses almost 8 GB of storage
While the Galaxy S5 made away with most of the bloat that was seen in the Galaxy S4, it looks like the official ROM still takes up a lot of space. The 16 GB variant of the Galaxy S5 will only have 7.8 GB available to the user, according to the storage page of a stock 16 GB Galaxy S5. The page mentions that the minimum amount of space that is required to run the system is 5.28 GB, with miscellaneous files accounting for another 2.33 GB. A similar situation was seen on the 16 GB Galaxy S4, which only had 8.8 GB available to users.
A stock 16 GB Nexus 5 on the other hand has about 12.1 GB available the user, which means that TouchWiz and other Samsung utilities account for another 3.6 GB of storage. The Galaxy S5 does come with a micro-SD card slot that accommodates SD cards with 128 gigs of storage, so if you’re keen on using the Galaxy S5 for shooting 4K video, you’d best get one of those as even the 32 GB variant will likely not be sufficient.