Units and constants

Units are known in Physics mode. In the other modes write them in \mathrm{…}. A unit symbol is looked up as a whole, so min is the minute (not $m \cdot i \cdot n$), mN the millinewton and Pa the pascal.

SI units

These take every metric prefix (km, mA, µF, GHz, …).

Quantity	Unit	Symbol
length	metre	m
mass	gram, kilogram	g, kg
time	second	s
electric current	ampere	A
temperature	kelvin, degree Celsius	K, °C
amount of substance	mole	mol
luminous intensity	candela	cd
angle, solid angle	radian, steradian	rad, sr
frequency	hertz	Hz
force	newton	N
pressure	pascal	Pa
energy	joule	J
power	watt	W
electric charge	coulomb	C
voltage	volt	V
capacitance	farad	F
resistance	ohm	\Omega, Ohm
conductance	siemens	S
magnetic flux	weber	Wb
magnetic flux density	tesla	T
inductance	henry	H
luminous flux, illuminance	lumen, lux	lm, lx
activity	becquerel	Bq
absorbed dose, dose equivalent	gray, sievert	Gy, Sv
catalytic activity	katal	kat

Prefixes: q r y z a f p n µ m c d da h k M G T P E Z Y R Q. Micro can be typed as µ, μ or \mu (3\mu F); u is not micro but the dalton.

Other units

Unit	Symbol	Prefixes
litre	l	yes
minute, hour, day, week	min, h, d (day), wk (week)
month, year	mo (mon, month), yr (year; a and y see below)
electronvolt	eV	yes
bar, atmosphere, torr	bar, atm, Torr	bar only
calorie, watt-hour	cal, Wh	yes (kcal, kWh)
hectare	ha
ångström	Å (\AA)
mile per hour	mph
light-year, astronomical unit	ly, AU
dalton	Da (u, see below)
percent	\%
tonne, inch	t, in (see below)

Some letters are variables by default because they are more often meant that way. Two settings under Settings → Input turn them into units:

Letters	Unit	Setting
a, y	year	a and y as variables off
t, u, in	tonne, dalton, inch	t, u and in as units on

Named results

A result whose unit came out of the arithmetic is written with the named unit of its dimension, if there is one: $\mathrm{kg \cdot m/s^2}$ becomes $\mathrm{N}$. Units you typed yourself are kept (72\frac{km}{h} stays in $\mathrm{km/h}$). Where two units share a dimension, the first wins: hertz over becquerel, gray over sievert, kelvin over degree Celsius.

The result also carries the name of the quantity (force, velocity, density, …), which the error messages use too: m (length) and s (time) cannot be added.

Physical constants

Physics mode only (CODATA 2018). A session variable with the same name wins.

Constant	Input	Value
speed of light	c_0	$299792458\,\mathrm{m/s}$
Planck constant	h_P	$6{,}62607015 \cdot 10^{-34}\,\mathrm{J \cdot s}$
reduced Planck constant	\hbar	$h_P / 2\pi$
Boltzmann constant	k_B	$1{,}380649 \cdot 10^{-23}\,\mathrm{J/K}$
Avogadro constant	N_A	$6{,}02214076 \cdot 10^{23}\,\mathrm{mol^{-1}}$
molar gas constant	R_m	$8{,}31446261815324\,\mathrm{J/(mol \cdot K)}$
elementary charge	e_0	$1{,}602176634 \cdot 10^{-19}\,\mathrm{C}$
vacuum permittivity	\varepsilon_0, \epsilon_0	$8{,}8541878128 \cdot 10^{-12}\,\mathrm{F/m}$
vacuum permeability	\mu_0	$1{,}25663706212 \cdot 10^{-6}\,\mathrm{N/A^2}$
electron, proton, neutron mass	m_e, m_p, m_n	$9{,}109\ldots \cdot 10^{-31}\,\mathrm{kg}$, …
Stefan–Boltzmann constant	\sigma_SB	$5{,}670374419 \cdot 10^{-8}\,\mathrm{W/(m^2 \cdot K^4)}$
standard gravity	g_n	$9{,}80665\,\mathrm{m/s^2}$
gravitational constant	G_N	$6{,}67430 \cdot 10^{-11}\,\mathrm{m^3/(kg \cdot s^2)}$