Measure · 22 special names

Derived units

Every other SI unit is a product of powers of the seven base units. Twenty-two of them have their own names, from the radian to the katal; the rest are written out, like metre per second.

Symbol	Name	Quantity	In other SI units	In base units
rad	radian	plane angle	m/m	1
sr	steradian	solid angle	m²/m²	1
Hz	hertz	frequency	—	s⁻¹
N	newton	force	—	kg m s⁻²
Pa	pascal	pressure, stress	N/m²	kg m⁻¹ s⁻²
J	joule	energy, work, heat	N m	kg m² s⁻²
W	watt	power	J/s	kg m² s⁻³
C	coulomb	electric charge	—	A s
V	volt	electric potential difference	W/A	kg m² s⁻³ A⁻¹
F	farad	capacitance	C/V	kg⁻¹ m⁻² s⁴ A²
Ω	ohm	electric resistance	V/A	kg m² s⁻³ A⁻²
S	siemens	electric conductance	A/V	kg⁻¹ m⁻² s³ A²
Wb	weber	magnetic flux	V s	kg m² s⁻² A⁻¹
T	tesla	magnetic flux density	Wb/m²	kg s⁻² A⁻¹
H	henry	inductance	Wb/A	kg m² s⁻² A⁻²
°C	degree Celsius	Celsius temperature	—	K
lm	lumen	luminous flux	cd sr	cd sr
lx	lux	illuminance	lm/m²	cd sr m⁻²
Bq	becquerel	activity of a radionuclide	—	s⁻¹
Gy	gray	absorbed dose	J/kg	m² s⁻²
Sv	sievert	dose equivalent	J/kg	m² s⁻²
kat	katal	catalytic activity	—	mol s⁻¹

Source: The International System of Units (SI), 9th edition (2019), with later updates, Table 4.

Same unit, different quantity

The gray and the sievert are both J/kg, and the hertz and the becquerel are both s⁻¹. The special names exist precisely so that a dose or a radioactivity is never confused with something else of the same dimension.