Dimensionless units

NOTE The units ppb and ppt are deprecated because the names "billion" and "trillion" are ambiguous.

Symbol (c/s)

Display Name

Print Symbol

Kind of Quantity

Metric

10* 

the number ten for arbitrary powers 

10n 

no

10^ 

the number ten for arbitrary powers 

10n 

no

[pi] 

the number pi 

π 

no

percent 

no

[ppth] 

parts per thousand 

ppth 

no

[ppm] 

parts per million 

ppm 

no

[ppb] 

parts per billion 

ppb 

no

[pptr] 

parts per trillion 

pptr 

no

SI units

NOTE Defined by CGPM (General Conference on Weights and Measures).

Symbol (c/s)

Display Name

Print Symbol

Kind of Quantity

Metric

mol 

mole 

mol 

amount of substance 

yes

sr 

steradian 

sr 

solid angle 

yes

Hz 

hertz 

Hz 

frequency 

yes

newton 

force 

yes

Pa 

pascal 

Pa 

pressure 

yes

joule 

energy 

yes

watt 

power 

yes

ampère 

electric current 

yes

volt 

electric potential 

yes

farad 

electric capacitance 

yes

Ohm 

ohm 

Ω 

electric resistance 

yes

siemens 

electric conductance 

yes

Wb 

weber 

Wb 

magnetic flux 

yes

Cel 

degree Celsius 

°C 

temperature 

yes

tesla 

magnetic flux density 

yes

henry 

inductance 

yes

lm 

lumen 

lm 

luminous flux 

yes

lx 

lux 

lx 

illuminance 

yes

Bq 

becquerel 

Bq 

radioactivity 

yes

Gy 

gray 

Gy 

energy dose 

yes

Sv 

sievert 

Sv 

dose equivalent 

yes

Other units from ISO 1000, ISO 2955, and some from ANSI X3.50.

Symbol (c/s)

Display Name

Print Symbol

Kind of Quantity

Metric

gon 

gon, grade 

□g 

plane angle 

no

deg 

degree 

° 

plane angle 

no

minute 

plane angle 

no

'' 

second 

'' 

plane angle 

no

liter 

volume 

yes

liter 

volume 

yes

ar 

are 

area 

yes

min 

minute 

min 

time 

no

hour 

time 

no

day 

time 

no

a_t 

tropical year 

at 

time 

no

a_j 

mean Julian year 

aj 

time 

no

a_g 

mean Gregorian year 

ag 

time 

no

year 

time 

no

wk 

week 

wk 

time 

no

mo_s 

synodal month 

mos 

time 

no

mo_j 

mean Julian month 

moj 

time 

no

mo_g 

mean Gregorian month 

mog 

time 

no

mo 

month 

mo 

time 

no

tonne 

mass 

yes

bar 

bar 

bar 

pressure 

yes

unified atomic mass unit 

mass 

yes

eV 

electronvolt 

eV 

energy 

yes

AU 

astronomic unit 

AU 

length 

no

pc 

parsec 

pc 

length 

yes

Natural unit

NOTE Fundamental constants of nature and units derived from these constants.

Symbol (c/s)

Display Name

Print Symbol

Kind of Quantity

Metric

[c] 

velocity of light 

velocity 

yes

[h] 

Planck constant 

action 

yes

[k] 

Boltzmann constant 

(unclassified) 

yes

[eps_0] 

permittivity of vacuum 

ε0 

electric permittivity 

yes

[mu_0] 

permeability of vacuum 

μ0 

magnetic permeability 

yes

[e] 

elementary charge 

electric charge 

yes

[m_e] 

electron mass 

me 

mass 

yes

[m_p] 

proton mass 

mp 

mass 

yes

[G] 

Newtonian constant of gravitation 

(unclassified) 

yes

[g] 

standard acceleration of free fall 

gn 

acceleration 

yes

atm 

standard atmosphere 

atm 

pressure 

no

[ly] 

light-year 

l.y. 

length 

yes

gf 

gram-force 

gf 

force 

yes

[lbf_av] 

pound force 

lbf 

force 

no

CGS units

NOTE The units of the older Centimeter-Gram-Second (CGS) system.

Symbol (c/s)

Display Name

Print Symbol

Kind of Quantity

Metric

Ky 

Kayser 

lineic number 

yes

Gal 

Gal 

Gal 

acceleration 

yes

dyn 

dyne 

dyn 

force 

yes

erg 

erg 

erg 

energy 

yes

Poise 

dynamic viscosity 

yes

Bi 

Biot 

Bi 

electric current 

yes

St 

Stokes 

St 

kinematic viscosity 

yes

Mx 

Maxwell 

Mx 

flux of magnetic induction 

yes

Gauss 

Gs, G 

magnetic flux density 

yes

Oe 

Oersted 

Oe 

magnetic field intensity 

yes

Gb 

Gilbert 

Gb 

magnetic tension 

yes

sb 

stilb 

sb 

lum. intensity density 

yes

Lmb 

Lambert 

brightness 

yes

ph 

phot 

ph 

illuminance 

yes

Ci 

Curie 

Ci 

radioactivity 

yes

Roentgen 

ion dose 

yes

RAD 

radiation absorbed dose 

RAD 

energy dose 

yes

REM 

radiation equivalent man 

REM 

dose equivalent 

yes