SI defines 7 base units: s, m, kg, A, K, mol, cd.
There are 22 of derived units with their own symbols defined.
These correspond to the base ones like so:
Derived unit | Equivalent using base units |
---|
rad | 1 |
sr | 1 |
Hz | s^-1 |
N | kg m s^-2 |
Pa | kg m^-1 s^-2 |
J | kg m^2 s^-2 |
Derived unit | Equivalent using base units |
---|
W | kg m^2 s^-3 |
C | A s |
V | kg m^2 s^-3 A^-1 |
F | kg^-1 m^-2 s^4 A^2 |
Ω | kg m^2 s^-3 A^-2 |
S | kg^-1 m^-2 s^3 A^2 |
Derived unit | Equivalent using base units |
---|
Wb | kg m^2 s^-2 A^-1 |
T | kg s^-2 A^-1 |
H | kg m^2 s^-2 A^-2 |
°C | K |
lm | cd |
lx | cd m^-2 |
Derived unit | Equivalent using base units |
---|
Bq | s^-1 |
Gy | m^2 s^-2 |
Sv | m^2 s^-2 |
kat | mol s^-1 |
SI further defines 24 prefixes denoting exponents of 10:
Symbol | Quantity |
---|
Q | 10^30 |
R | 10^27 |
Y | 10^24 |
Z | 10^21 |
E | 10^18 |
P | 10^15 |
Symbol | Quantity |
---|
T | 10^12 |
G | 10^9 |
M | 10^6 |
k | 10^3 |
h | 10^2 |
da | 10 |
Symbol | Quantity |
---|
d | 10^-1 |
c | 10^-2 |
m | 10^-3 |
μ | 10^-6 |
n | 10^-9 |
p | 10^-12 |
Symbol | Quantity |
---|
f | 10^-15 |
a | 10^-18 |
z | 10^-21 |
y | 10^-24 |
r | 10^-27 |
q | 10^-30 |
Each input comprises of a (optional) prefix and one of the base or derived
units symbol, except that symbols for decimal multiples and sub-multiples
of "kg" are formed by attaching prefixes to the unit symbol "g". For
example, "10^−6 kg" is written as "mg", not as "µkg". Each such input
should be convert to product of a power of 10 and a product of base units,
as described in the tables above. If the unit is "1", only the power of
ten should be printed. Furthermore, "10^1" should be printed as "10" and
"10^0" as "1". For example, "MJ" should be converted to "10^6 kg m^2 s^-2".