Metric Prefixes





Prefix Symbol 1000m 10n Decimal Short scale1 Long scale1
yotta Y 10008 1024 1,000,000,000,000,000,000,000,000.00 Septillion Quadrillion
zetta Z 10007 1021 1,000,000,000,000,000,000,000.00 Sextillion Trilliard
exa E 10006 1018 1,000,000,000,000,000,000.00 Quintillion Trillion
peta P 10005 1015 1,000,000,000,000,000.00 Quadrillion Billiard
tera T 10004 1012 1,000,000,000,000.00 Trillion Billion
giga G 10003 109 1,000,000,000.00 Billion Milliard
mega M 10002 106 1,000,000.00 Million
kilo k 10001 103 1,000.00 Thousand
hecto h 10002/3 102 100.00 Hundred
deca da 10001/3 101 10.00 Ten
    10000 100 1.00 One
deci d 1000-1/3 10-1 0.10 Tenth
centi c 1000-2/3 10-2 0.01 Hundredth
milli m 1000-1 10-3 0.001 Thousandth
micro µ 1000-2 10-6 0.000001 Millionth
nano n 1000-3 10-9 0.000000001 Billionth Milliardth
pico p 1000-4 10-12 0.000000000001 Trillionth Billionth
femto f 1000-5 10-15 0.000000000000001 Quadrillionth Billiardth
atto a 1000-6 10-18 0.000000000000000001 Quintillionth Trillionth
zepto z 1000-7 10-21 0.000000000000000000001 Sextillionth Trilliardth
yocto y 1000-8 10-24 0.000000000000000000000001 Septillionth Quadrillionth

Notes:

  1. The long and short scales are two of several large-number naming systems for integer powers of ten that use the same words with different meanings:
    Long scale: Every new term greater than million is one million times larger than the previous term. Thus, billion means a million millions (1012), trillion means a million billions (1018), and so on.
    Short scale: Every new term greater than million is one thousand times larger than the previous term. Thus, billion means a thousand millions (109), trillion means a thousand billions (1012), and so on.
    See Wikipedia for more information.