Which itself is for marketing reasons, a manufacturer would find it difficult to compete with others using units that make their drives look larger or cheaper at “same capacity”.
There is also the smaller amount w!ndows will secretly waste for its own pleasure (few GiB iirc). And an even smaller amount that gets wasted in partitioning. Usually around 5MiB, you can reduce it to 16kiB with some manual configuration in gdisk, or you can skip partition tables entirely for some end-game cursedness. And then the filesystem will take some. ext4 takes based on the number of inodes, for large drives that can be tens of GiB. Btrfs takes almost nothing (though in the background allocates in steps of 1GiB, so some tools might show 2GiB used as soon as data is written). Then if you try to sum all files on disk, that will land even lower for many more reasons.
Which itself is for marketing reasons, a manufacturer would find it difficult to compete with others using units that make their drives look larger or cheaper at “same capacity”.
There is also the smaller amount w!ndows will secretly waste for its own pleasure (few GiB iirc). And an even smaller amount that gets wasted in partitioning. Usually around 5MiB, you can reduce it to 16kiB with some manual configuration in gdisk, or you can skip partition tables entirely for some end-game cursedness. And then the filesystem will take some. ext4 takes based on the number of inodes, for large drives that can be tens of GiB. Btrfs takes almost nothing (though in the background allocates in steps of 1GiB, so some tools might show 2GiB used as soon as data is written). Then if you try to sum all files on disk, that will land even lower for many more reasons.