SI prefixes
| 1000m |
10n |
Prefix |
Symbol |
Since[1] |
Short scale |
Long scale |
Decimal |
| 10008 |
1024 |
yotta- |
Y |
1991 |
Septillion |
Quadrillion |
1 000 000 000 000 000 000 000 000 |
| 10007 |
1021 |
zetta- |
Z |
1991 |
Sextillion |
Trilliard |
1 000 000 000 000 000 000 000 |
| 10006 |
1018 |
exa- |
E |
1975 |
Quintillion |
Trillion |
1 000 000 000 000 000 000 |
| 10005 |
1015 |
peta- |
P |
1975 |
Quadrillion |
Billiard |
1 000 000 000 000 000 |
| 10004 |
1012 |
tera- |
T |
1960 |
Trillion |
Billion |
1 000 000 000 000 |
| 10003 |
109 |
giga- |
G |
1960 |
Billion |
Milliard |
1 000 000 000 |
| 10002 |
106 |
mega- |
M |
1960 |
Million |
1 000 000 |
| 10001 |
103 |
kilo- |
k |
1795 |
Thousand |
1 000 |
| 10002/3 |
102 |
hecto- |
h |
1795 |
Hundred |
100 |
| 10001/3 |
101 |
deca- |
da |
1795 |
Ten |
10 |
| 10000 |
100 |
(none) |
(none) |
NA |
One |
1 |
| 1000−1/3 |
10−1 |
deci- |
d |
1795 |
Tenth |
0.1 |
| 1000−2/3 |
10−2 |
centi- |
c |
1795 |
Hundredth |
0.01 |
| 1000−1 |
10−3 |
milli- |
m |
1795 |
Thousandth |
0.001 |
| 1000−2 |
10−6 |
micro- |
µ |
1960[2] |
Millionth |
0.000 001 |
| 1000−3 |
10−9 |
nano- |
n |
1960 |
Billionth |
Milliardth |
0.000 000 001 |
| 1000−4 |
10−12 |
pico- |
p |
1960 |
Trillionth |
Billionth |
0.000 000 000 001 |
| 1000−5 |
10−15 |
femto- |
f |
1964 |
Quadrillionth |
Billiardth |
0.000 000 000 000 001 |
| 1000−6 |
10−18 |
atto- |
a |
1964 |
Quintillionth |
Trillionth |
0.000 000 000 000 000 001 |
| 1000−7 |
10−21 |
zepto- |
z |
1991 |
Sextillionth |
Trilliardth |
0.000 000 000 000 000 000 001 |
| 1000−8 |
10−24 |
yocto- |
y |
1991 |
Septillionth |
Quadrillionth |
0.000 000 000 000 000 000 000 001 |
- The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM.
- The 1948 recognition of the micron by the CGPM was abrogated in 1967.
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