Table 1 SI Prefixes - Base 10
| Factor |
Prefix |
Symbol |
Ordinary Notation1 |
English (US2) |
| 101 |
deca |
da |
10 |
ten |
| 102 |
hecto |
h |
100 |
hundred |
| 103 |
kilo |
k |
1 000 |
thousand |
| 106 |
mega |
M |
1 000 000 |
million |
| 109 |
giga |
G |
1 000 000 000 |
billion2 |
| 1012 |
tera |
T |
1 000 000 000 000 |
trillion2 |
| 1015 |
peta |
P |
1 000 000 000 000 000 |
quadrillion2 |
| 1018 |
exa |
E |
1 000 000 000 000 000 000 |
quintillion2 |
| 1021 |
zetta |
Z |
1 000 000 000 000 000 000 000 |
sextillion2 |
| 1024 |
yotta |
Y |
1 000 000 000 000 000 000 000 000 |
septillion2 |
| |
|
|
|
|
| 10–1 |
deci |
d |
0,1 |
tenth |
| 10–2 |
centi |
c |
0,01 |
hundredth |
| 10–3 |
milli |
m |
0,001 |
thousandth |
| 10–6 |
micro |
µ |
0,000 001 |
millionth |
| 10–9 |
nano |
n |
0,000 000 001 |
billionth2 |
| 10–12 |
pico |
p |
0,000 000 000 001 |
trillionth2 |
| 10–15 |
femto |
f |
0,000 000 000 000 001 |
quadrillionth2 |
| 10–18 |
atto |
a |
0,000 000 000 000 000 001 |
quintillionth2 |
| 10–21 |
zepto |
z |
0,000 000 000 000 000 000 001 |
sextillionth2 |
| 10–24 |
yocto |
y |
0,000 000 000 000 000 000 000 001 |
septillionth2 |
| 1 |
Use space to separate numbers into groups of three digits
- never comma or dot. See also ISO-31 and Writing
Guidelines.
|
| 2 |
Terms like billion, trillion, etc are ambiguous. A Billion
in English English differ from a Billion in US English. See also What's
a Billion...? |
The SI prefixes above refer strictly
to powers of 10. They should not be used to indicate powers of 2 (for example,
one kilobit represents 1000 bits and
not 1024 bits).
Table 2 IEC Prefixes - Base 2 Binary
| Factor |
Name |
Symbol |
Origin |
Notes |
| 210 |
kibi |
Ki |
kilobinary: (210)1 |
1024 |
| 220 |
mebi |
Mi |
megabinary: (210)2 |
100 |
| 230 |
gibi |
Gi |
gigabinary: (210)3 |
1 048 576 |
| 240 |
tebi |
Ti |
terabinary: (210)4 |
1 073 741 824 |
| 250 |
pebi |
Pi |
petabinary: (210)5 |
1 099 511 627 776 |
| 260 |
exbi |
Ei |
exabinary: (210)6 |
1 125 899 906 842 624 |
| Examples and comparisons with SI prefixes |
| one kibibit |
1 Kibit = 210 bit = 1024 bit |
| one kilobit |
1 kbit = 103 bit = 1000 bit |
| one mebibyte |
1 MiB = 220 B = 1 048 576 B |
| one megabyte |
1 MB = 106 B = 1 000 000 B |
| one gibibyte |
1 GiB = 230 B = 1 073 741 824
B |
| one gigabyte |
1 GB = 109 B = 1 000 000 000 B |
From physics.nist.gov/cuu/Units/binary.html retrieved
2005-11-26
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