You pay for a 100 megabit internet connection, start a download, and the browser reports 12 megabytes per second. Nothing is broken and nobody is cheating you — you have just met the factor of eight that separates bits from bytes, hidden behind the difference between a lowercase b and an uppercase B. It is probably the most consequential capitalization rule in all of computing.
A bit is the smallest unit of digital information: a single 0 or 1. A byte is a group of eight bits, and it became the standard chunk because eight bits comfortably encode one character of text in classic encodings.
Why eight, anyway?
Early computers experimented with byte sizes from 4 to 9 bits, but 8 won decisively during the 1960s, helped by influential mainframe designs and the convenience of a power of two. Eight bits give 256 possible values — enough for the Latin alphabet in both cases, digits, punctuation, and control codes. Once memory chips, processors, and file formats all standardized on 8-bit bytes, the convention became effectively permanent, and today “byte” means 8 bits everywhere outside of historical trivia. The term “octet” survives in networking standards precisely because it is unambiguous.
Two units for two jobs
The split persists because the two units naturally measure different things. Transmission is a stream of individual bits on a wire or radio channel, so network speeds are quoted in bits per second: megabits (Mbps) and gigabits (Gbps). Storage holds data in byte-addressed chunks, so files and disks are measured in bytes: megabytes (MB), gigabytes (GB), terabytes (TB). Both camps are being internally consistent; confusion only arises at the boundary, when a download moves data from the bits world into the bytes world.
The conversion in practice
To translate a connection speed into file-transfer terms, divide by eight. A 100 Mbps connection moves at most 12.5 megabytes per second, so a 1 GB file needs at least 80 seconds under perfect conditions — real transfers add protocol overhead, so expect a bit longer. Going the other way, a game that downloads at 60 MB/s is consuming 480 Mbps of bandwidth. Watch the capitalization in specs: “Mb” is megabits, “MB” is megabytes, and marketing materials do not always use them carefully.
Whenever a speed and a size appear in the same sentence, check the case of the b, divide or multiply by eight as needed, and the numbers will finally agree with each other.
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