Amount Electric Current Luminosity Mass Temperature Time Length SI Units About Mole Mole Ampere Ampere Metre Metre Candela Candela Kilogram Kilogram Kelvin Kelvin Second Second
A metric prefix precedes a unit of measurement and indicates a multiple or fraction of that unit. For example, kilo may be added to metre to indicate 1000 metres, i.e. there are 1000 metres in a kilometre. Likewise, milli may be added may be added to metre to form the word millimetre, i.e. one thousandth of a metre. The table below gives the names and symbols of all metric prefixes in common use, together with their multiple or fraction quantity. These are given in the form 10^n, where, for example, 103 is written as 10^3, and 10-3 is written as 10^-3. In addition, the short and long scale names are given. The short scale names are now used in most English speaking countries. Note that there are some exceptions. For example, as a consequence of binary mathematics, when discussing a computer’s memory or storage capacity a kilobyte (kB, KB, kbyte or Kbyte) is 1,024 bytes, i.e. 2^10 bytes. Likewise, most standards bodies now regard a megabyte as being 1,024,000 bytes, i.e. 1000 x 1024 bytes.
Derived Units
Name / Symbol   10^n       Short scale       Long scale
SI Units Explained - Metric Prefixes
yotta Y 10^24       septillion           quadrillion Decimal    =    1000000000000000000000000 zetta Z 10^21       sextillion       thousand trillion (trilliard) Decimal =   1000000000000000000000 exa E 10^18      quintillion       trillion   Decimal   =   1000000000000000000 peta P 10^15      quadrillion       thousand billion (billiard)   Decimal   =   1000000000000000 tera T 10^12      trillion       billion   Decimal   =   1000000000000 giga G 10^9      billion     thousand million (milliard)   Decimal   =   1000000000 mega M 10^6     million     million   Decimal   =  1000000 kilo k 10^3     thousand     thousand   Decimal   =  1000 hecto h 10^2     hundred     hundred   Decimal   =  100 deca h         10^1      ten     ten   Decimal   =   10 Un-named 10^0              one     one   Decimal   =   1 deci d 10^-1             tenth     tenth   Decimal =   0.1 centi c 10^-2      hundredth    hundredth   Decimal =   0.01 milli m 10^-3     thousandth    thousandth   Decimal   =  0.001 micro μ 10^-6     millionth    millionth   Decimal  =   0.000001 nano n 10^-9     billionth    thousand millionth   Decimal  =  0.000000001 pico p 10^-12     trillionth    billionth   Decimal  =   0.000000000001 femto f 10^-15    quadrillionth    thousand billionth   Decimal  =   0.000000000000001 atto a 10^-18   quintillionth    trillionth   Decimal  =  0.000000000000000001 zepto z 10^-21   sextillionth         thousand trillionth   Decimal  =  0.000000000000000000001 yocto y 10^-24   septillionth   quadrillionth   Decimal  =  0.000000000000000000000001
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