Oh, Those Terrible Units

Author: Szymon Lipiński
Published at: 2010-05-06

There are some numbers and units. Numbers are numbers. Units are units. Numbers informs how many. Units inform about two things:

The SI Base Units

Name Unit Symbol Quantity
metre m length
kilogram kg mass
second s time
ampere A electric current
kelvin K thermodynamic temperature
candela cd luminous intensity
mole mol amount of substance

IT Base Units

Name Unit Symbol Quantity
bit b number of bits
byte B number of bytes
bits per second bps number of bits per second

Have you seen the difference? BYTES and BITS?

The Word Of Truth

SI Prefixes

name sumbol factor
kilo k 10^3
mega M 10^6
giga G 10^9
tera T 10^12
peta P 10^15
exa E 10^16

These symbols are used for avoiding too many zeros. So instead of 1000m you can write 1km and instead of 1000000B you can write 1GB. This is another problem. Normally 1 kilobyte = 1024 bytes. Yea, the IT world is wierd. For distinguishing between 10^3 = 1000 and 2^10 = 1024 someone created some binary system:

name sumbol factor
kibi Ki 1024^1
mebi Mi 1024^2
gibi Gi 1024^3
tebi Ti 1024^4
pebi Pi 1024^5
exbi Ei 1024^6

Now we’ve got 1024B = 1KiB and so on.

The Problem

Why am I writing all that? Because I don’t understand why many people in the IT world, including many programmers, still don’t know that this is important to write according to some standards. This is like a language: you have to use the correct grammar so others have the chance to understand correctly what you say.

Some Examples From Web

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