John's Metric System Reference Page

I am a believer. I believe that the world would be a better and simpler place to live if we could all agree on our system of units! We would also crash fewer spacecraft into Mars... So, as a public service, I am providing this handy reference page for the Système Internationale (SI).

Metric System Base Units

These are the only base units recognized by the SI. All other units (joules, becquerels, watts, coulombs) are derived units. A comprehensive and handy one-page chart showing the derived units and their relationships to the base units is available in this pdf file: derived_units.pdf

Quantity measured Unit Abbreviation
length meter m
mass kilogram kg
time second s
electric current ampere A
temperature kelvin K
(not °K)
luminous intensity candela cd
amount of substance mole mol
Note that K is for kelvin, not "degrees kelvin".

Prefixes for expressing powers

 Multiplier   Prefix   Symbol 
1024 yotta Y
1021 zetta Z
1018 exa E
1015 peta P
1012 tera T
109 giga G
106 mega M
103 kilo k
102 hecto h
10 deca da
10-1 deci d
10-2 centi c
10-3 milli m
10-6 micro μ
10-9 nano n
10-12 pico p
10-15 femto f
10-18 atto a
10-21 zepto z
10-24 yocto y
Anything greater than 1024 is a "lotta"
and anything less than 10-24 is "notta".
That's a joke, son. That's a joke.

Some Handy Metrication Links