– What’s the Practical Purpose for Using MiB (Mebibytes) Over MB (Megabytes) or Vice Versa?
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It’s easier to understand for a smaller number like the kB and kiB. A kB is, strictly speaking, 1000 bytes whereas a kiB is 1024 bytes. The reason we might use the second is that, if we had a computer with 10 address bits (10 wires coming out telling the memory which byte it wanted) then it could choose amongst 1024 bytes. That’s because each address wire has either a high or low voltage—two possibilities—and two possibilities to the power of ten wires is 2^(10)=1024 possibilities.
* 1 MB is 1000^2 bytes or 1000000 bytes.
* 1 MiB is 1024^2 bytes or 1048576 bytes.
Originally computer scientists just said MB when they meant MiB, assuming you could tell by context what they meant, but later MiB was created to make the meaning unambiguous.
MiB used to be used for things like hard disk drives too but now it’s more restricted to CPUs, memory (RAM) and some devices. Hard disks have mostly changed to being sized by GB and TB rather than GiB and TiB, even though the smallest unit of disk drive storage, the block, is still 0.5kiB or 4kiB.
A reason for preferring MB over MiB is mostly that it’s a real round number in our familiar base ten. Communications tends to work in multiples of ten, like Fast Ethernet is exactly 100Mbps (bit per second). The kiB, MiB, GiB and TiB units are messy because they get farther from their base ten equivalents with each step up:
* 1 kiB = 1.024 kB
* 1 MiB ≈ 1.049 MB
* 1 GiB ≈ 1.074 GB
* 1 TiB ≈ 1.100 TB
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