×
SI Prefixes
Prefix
Base
Decimal
English word
Name
Symbol
1000
10
Short scalea
Long scalea
yotta
Y
10008
1024
1 000 000 000 000 000 000 000 000
septillion
quadrillion
zetta
Z
10007
1021
1 000 000 000 000 000 000 000
sextillion
trilliard
exa
E
10006
1018
1 000 000 000 000 000 000
quintillion
trillion
peta
P
10005
1015
1 000 000 000 000 000
quadrillion
billiard
tera
T
10004
1012
1 000 000 000 000
trillion
billion
giga
G
10003
109
1 000 000 000
billion
milliard
mega
M
10002
106
1 000 000
million
kilo
K
10001
103
1 000
thousand
hecto
h
10002/3
102
100
hundred
deca
da
10001/3
101
10
ten
10000
100
1
one
deci
d
1000-1/3
10-1
0.1
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
0.000 001
millionth
nano
n
1000-3
10-9
0.000 000 001
billionth
milliardth
pico
p
1000-4
10-12
0.000 000 000 001
trillionth
billionth
femto
f
1000-5
10-15
0.000 000 000 000 001
quadrillionth
billiardth
atto
a
1000-6
10-18
0.000 000 000 000 000 001
quitillionth
trillionth
zepto
z
1000-7
10-21
0.000 000 000 000 000 000 001
sextillionth
trilliardth
yocto
y
1000-8
10-24
0.000 000 000 000 000 000 000 001
septillionth
quadrillionth
Metric prefixes in everyday use
Text
Symbol
Factor
Power
yotta
Y
1 000 000 000 000 000 000 000 000
1024
zetta
Z
1 000 000 000 000 000 000 000
1021
exa
E
1 000 000 000 000 000 000
1018
peta
P
1 000 000 000 000 000
1015
tera
T
1 000 000 000 000
1012
giga
G
1 000 000 000
109
mega
M
1 000 000
106
kilo
K
1 000
103
hecto
h
100
102
deca
da
10
101
(none)
(none)
1
100
deci
d
0.1
10-1
centi
c
0.01
10-2
milli
m
0.001
10-3
micro
µ
0.000 001
10-6
nano
n
0.000 000 001
10-9
pico
p
0.000 000 000 001
10-12
femto
f
0.000 000 000 000 001
10-15
atto
a
0.000 000 000 000 000 001
10-18
zepto
z
0.000 000 000 000 000 000 001
10-21
yocto
y
0.000 000 000 000 000 000 000 001
10-24
Standard prefixes for the SI units of measure
Multiples
Prefix name
deca
hecto
kilo
mega
giga
tera
peta
exa
zetta
yotta
Prefix symbol
da
h
k
M
G
T
P
E
Z
Y
Factor
100
101
102
103
106
109
1012
1015
1018
1021
1024
Submultiples
Prefix name
deci
centi
milli
micro
nano
pico
femto
atto
zepto
yocto
Prefix symbol
d
c
m
µ
n
p
f
a
z
y
Factor
100
101
102
103
106
109
1012
1015
1018
1021
1024
Click to enlarge .
^ 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.
The long scale is based on powers of one million, whereas the short scale is based on powers of one thousand.
The short scale has an offset, unlike the long scale.[4]
