International Units : MB/GB or MiB/GiB

Standard IEC prefixes and descriptions for binary multiples were introduced in 1998/99 but are still widely misused.

Decimal numbers

Prefixes MB, GB, TB, PB, ...
Descriptive terms (mega, giga, tera, peta, exa - bytes).

Binary numbers (Power of 2)

Prefixes MiB, GiB,TiB, PiB, EiB, ZiB,YiB
Descriptive terms (mebi, gibi, tebi, pebi, exbi - bytes).

Decimal
Disk drives, DVD capacity
Power of 2 (binary)
RAM, CD capacity
KB 1000 bytes KiB = 2^10 =1,024 bytes
MB 1000^2 = 1000,000 bytes MiB = 2^20 = 1024^2 =1,048,576 bytes
GB 1000^3 =1000,000,000 bytes GiB = 2^30 = 1024^3 =1,073,741,824 bytes
TB: 1000^4 =1000,000,000,000 TiB = 2^40 = 1024^4 =1,099,511,627,776 bytes
PB: 1000^5 =1000,000,000,000,000 PiB = 2^50 = 1024^5
EB: 1000^6 =1000,000,000,000,000,000 EiB = 2^60 = 1024^6
ZB: 1000^7 ZiB = 2^70 = 1024^7
YB: 1000^8 YiB = 2^80 = 1024^8

Any of the above can be entered directly into a spreadsheet e.g. =1024^3 will give 1 GiB

In PowerShell you can enter units with the decimal shortcut notation 1MB, 1GB, 1TB, 1PB etc, however this will incorrectly expand to a Power of 2 value: 1024, 1048576 etc.

Hard drive manufacturers market disk drives in decimal (base 10) capacity GB.

Network speeds

A 100 megabit network has a capacity of 100,000,000 bits per second.
Data Transfer packets are normally 64 KB = 65,536 Bytes or 524,288 bits (bits = Bytes x 8 )

So in this example the network would transfer around 200 packets per second.

“Failure of the NASA Mars Climate Orbiter occurred because the flight system software was written using metric units, while the ground crew were entering course correction and thruster data using Imperial measures”

Related

Bytes.xls - Convert between KB/GB/KiB/GiB/PiB/Zib etc or use the web page version:
Convert bytes / KB/ MB / KiB / MiB / GB / GiB
The bash utility units can convert e.g. units -t '500GB' 'GiB'


 
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