List of common physics notations

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This is a list of common physical constants and variables, and their notations. Note that bold text indicates that the quantity is a vector.

Latin characters[edit]

Symbol Meaning SI unit of measure
area meter squared (m2)
magnetic vector potential
amplitude meter
acceleration meters per second squared (m/s2)
magnetic flux density
also called the magnetic field density or magnetic induction
tesla (T), or equivalently,
weber per square meter (Wb/m2)
capacitance farad (F)
heat capacity joule per kelvin (J K−1), or equivalently, joule per degree Celsius (J °C−1)
constant of integration varied depending on context
speed of light (in vacuum) 299,792,458 meter per second (m/s)
speed of sound 340.29 meter per second (m/s)
specific heat capacity joule per kilogram per kelvin (J kg−1 K−1), or equivalently, joule per kilogram per degree Celsius (J kg−1 °C−1)
viscous damping coefficient kilogram per second (kg/s)
electric displacement field
also called the electric flux density
coulomb per square meter (C/m2)
density kilograms per cubic meter (kg/m3)
distance meter (m)
direction unitless
impact parameter meter (m)
diameter meter (m)
differential (e.g. )
differential vector element of surface area A, with infinitesimally

small magnitude and direction normal to surface S

square meter (m2)
differential element of volume V enclosed by surface S cubic meter (m3)
electric field newton per coulomb (N C−1), or equivalently, volt per meter (V m−1)
energy joule (J)
Young's Modulus Pascal (Pa) or Newton per square meter (N/m2) or kilogram per meter per second squared (kg·m−1·s−2)
eccentricity unitless
2.71828... (base of the natural logarithm), electron, elementary charge
force newton (N)
frequency hertz (Hz)
friction newton (N)
the gravitational constant newton meter squared per kilogram squared (N m2/kg2)
acceleration due to gravity meter per second squared (m/s2), or equivalently, newton per kilogramme (N/kg)
magnetic field strength
also called just magnetic field
ampere per meter (A/m)
Hamiltonian joule (J)
height meter (m)
Planck's constant joule second (J s)
reduced Planck's constant joule second (J s)
action joule second (J s)
intensity watt per square meter (W/m2)
sound intensity watt per square meter (W/m2)
electric current ampere (A)
moment of inertia kilogram meter squared (kg m2)
intensity watt per square meter (W/m2)
imaginary unit
Cartesian x-axis basis unit vector unitless
free current density,
not including polarization or magnetization currents bound in a material
ampere per square meter (A/m2)
impulse kilogram meter per second (kg m/s)
Cartesian y-axis basis unit vector unitless
kinetic energy


joule (J)
Boltzmann constant joule per kelvin (J/K)
wavenumber radians per meter (m−1)
Cartesian z-axis basis unit vector unitless
inductance henry (H)
luminosity watt (W)
angular momentum newton meter second (N m s or kg m2 s−1)
length meter (m)
magnetization ampere per meter (A/m)
moment of force
often simply called moment or torque
newton meter (N m)
mass kilogram (kg)
normal vector unit varies depending on context
atomic number unitless
refractive index unitless
principal quantum number unitless
power watt (W)
momentum kilogram meter per second (kg m/s)
pressure pascal (Pa)
electric charge coulomb (C)
Heat joule (J)
electric charge coulomb (C)
electrical resistance ohm (Ω)
Ricci tensor unitless
gas constant joule per kilogramme kelvin (J/kgK)
radius vector (position) meter (m)
radius of rotation or distance between two things such as the masses in Newton's law of universal gravitation meter (m)
surface area m2
entropy joule per kelvin (J/K)
arc length meter (m)
period second (s)
thermodynamic temperature
also called absolute temperature
kelvin (K)
time second (s)
four-velocity meter per second (m/s)
potential energy joule (J)
internal energy joule (J)
relativistic mass kilogram (kg)
energy density joule per cubic meter (J/m3) or joule per kilogram (J/kg) depending on the context
also called electric potential difference
volt (V)
volume cubic meter (m3)
shear force
velocity meter per second (m/s)
mechanical work joule (J)
width meter (m)
a generic unknown varied depending on context
displacement meter (m)
electrical impedance ohm (Ω)

Greek characters[edit]

Symbol Name Meaning SI unit of measure
alpha angular acceleration radian per second squared (rad/s2)
beta velocity in terms of the speed of light c unitless
gamma Lorentz factor unitless
gamma ray
shear strain
Heat capacity ratio unitless
delta a change in a variable (e.g. ) unitless
Laplace operator
delta displacement (usually small)
epsilon permittivity farad per meter (F/m)
strain unitless
ε0 epsilon


The vacuum permittivity constant
zeta damping ratio unitless
eta energy efficiency unitless
coefficient of viscosity
also called simply viscosity
pascal second (Pa s)
theta angular displacement radian (rad)
kappa torsion coefficient
also called torsion constant
newton meter per radian (N m/rad)
lambda cosmological constant per second squared (s−2)
wavelength meter (m)
mu magnetic moment ampere square meter (A m2)
coefficient of friction unitless
dynamic viscosity Pascal second (Pa s)
permeability (electromagnetism) Henry per meter (H/m)
reduced mass kilogram (kg)
nu frequency hertz (Hz)
kinematic viscosity meters squared per second (m2/s)
pi 3.14159... (irrational number)
rho mass density
usually simply called density
kilogram per cubic meter (kg/m3)
free electric charge density,
not including dipole charges bound in a material
coulomb per cubic meter (C/m3)
resistivity Ohm meter ( m)
sigma summation operator
sigma electrical conductivity Siemens per meter (S/m)
normal stress
tau torque newton meter (N m)
shear stress
time constant second (s)
6.28318... ()
phi field strength unit varies depending on context
magnetic flux Weber (Wb)
phi electric potential

Higgs Field

psi wave function unitless
omega angular frequency


radian per second (rad/s)
omega electric resistance ohm

Other characters[edit]

Symbol Name Meaning SI unit of measure
nabla dot the divergence operator
often pronounced "del dot"
per meter (m−1)
nabla cross the curl operator
often pronounced "del cross"
per meter (m−1)
nabla del (differential operator)
Delta the Laplace operator per square meter (m−2)
"der", "dow", "die", "partial" or simply "d" partial derivative (e.g. )
D'Alembert operator

See also[edit]

Generally used symbols