2026-05-11
TL;DR:
Computers (like that storage device of yours) work in binary units (powers of 2), rather than decimal units (powers of 10). It's a good idea to switch your units to binary so that you know just how much space you're working with.
Storage devices write and erase data based on their specific "write block size" (WBS) and "erase block size" (EBS), respectively. If these values are known, then storage can be aligned to the greatest common factor of the WBS and EBS. I'll call that the "alignment unit" for now.
For example, if the storage is aligned to this "alignment unit" (let's say, 4KiB), and we do a write of 4KiB. Any data written to it lines up with erase block and write block boundaries. The device would be able to write to the exact number of blocks requested.
However, if the storage is not aligned, and that same write happens to straddle two write blocks, 8KiB must be written for 4KiB of useful work. It goes the same way for erase blocks, so when erasing that 4KiB of data, 8KiB is erased.
Most devices don't directly tell what their WBS and EBS are, so 1MiB has been used as a good estimate for our "allignment unit" that works for nearly all modern devices.
Further reading here.
This one's self explanatory. Just make sure you know how much space your desired filesystem requires before making the partition.