60 s
minute
min
period of time equal to 60 seconds
60 min
hour
h
hr
period of time equal to 60 minutes
24 h
day
d
period of time equal to 24 hours
This "unit" is useful in the definition of subsequent units.
3.141592653589793238462643383279
pi
π
mathematical constant equal to the ratio of a circle's circumference to its diameter
(pi/180) rad
arc_degree
°
angular_degree
degree
arcdeg
measurement of a plane angle representing 1/360 of a full rotation
°/60
arc_minute
'
′
angular_minute
arcminute
arcmin
measurement of a plane angle equal to 1/60 arc degree
'/60
arc_second
"
″
angular_second
arcsecond
arcsec
measurement of a plane angle equal to 1/60 arc minute
The definition is exact. From 1901 to 1964, however, 1 liter was 1.000028 dm^3 (volume of 1 kg of water under standard conditions).
dm^3
liter
L
litre
l
unit of capacity equal to 1000 cubic centimeters
1000 kg
metric_ton
t
tonne
unit of weight equal to 1000 kilograms
Unit's value is obtained experimentally
1.60217733e-19 J
electronvolt
eV
electron_volt
unit of energy equal to the work accelerating an electron through a potential difference of one volt
Unit's value is obtained experimentally
1.6605402e-27 kg
unified_atomic_mass_unit
u
atomic_mass_unit
atomicmassunit
amu
standard unit for indicating mass on an atomic or molecular scale; is approximately the mass of one nucleon (either a single proton or neutron), and equivalent to 1 g/mol
According to resolution by the International Astronomical Union (IAU) in 2012
1.49597870700e11 m
astronomical_unit
au
Exact definition according to 2012 resolution by the International Astronomical Union (IAU). Ostensibly equal to the mean distance from the center of the earth to the center of the sun.
Pre-2012 resolution by the IAU
1.495979e11 m
astronomical_unit_BIPM_2006
ua
unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun according to the International Bureau of Weights and Measures (BIPM) in 2006
Unit is temporarily accepted for use with the SI.
1852 m
nautical_mile
unit of distance at sea, set at 1852 meters (approximately one minute of arc measured along any meridian)
Unit is temporarily accepted for use with the SI.
nautical_mile/hour
international_knot
knot_international
knot
derived unit of speed at sea
Unit is temporarily accepted for use with the SI.
1e-10 m
angstrom
ångström
Å
Å
unit of length equal to one hundred-millionth of a centimeter (1 meter/10**10)
Unit is temporarily accepted for use with the SI.
dam^2
are
a
unit of area equal to 100 square meters
Unit is temporarily accepted for use with the SI.
100 are
hectare
unit of area equal to 100 are ('hectoare'), or 10000 square meters
Unit is temporarily accepted for use with the SI.
100 fm^2
barn
b
unit of area, approximately the cross-sectional area of a uranium nucleus (10e-28 square meters)
Unit is temporarily accepted for use with the SI.
1000 hPa
bar
unit of pressure equal to 100000 Pascals, or about 0.987 atmospheres of pressure
Unit is temporarily accepted for use with the SI.
cm/s^2
gal
unit of acceleration equal to 1 cm per second squared
Unit is temporarily accepted for use with the SI.
3.7e10 Bq
curie
Ci
unit of radioactivity corresponding to 3.7 * 10e10 disintegrations per second
Unit is temporarily accepted for use with the SI.
2.58e-4 C/kg
roentgen
R
unit of ionizing radiation, the amount producing one electrostatic unit of positive or negative ionic charge in one cubic centimeter of air under standard conditions; rarely used
Unit is temporarily accepted for use with the SI.
cSv
rem
unit of radiation dosage applied to humans; equal to one hundredth of a sievert