Distance
1 meter
Distance is defined by distance light travels in vacuum during
1/299 792 458 of a second. See http://physics.nist.gov/cuu/Units/meter.html
and http://en.wikipedia.org/wiki/Meter
Kilometer
km
1000
1 kilometer is 1000 meters.
Meter
m
1
1 meter is the standard unit of distance.
Centimeter
cm
0.01
1 centimeter is 1/100 of a meter.
Millimeter
mm
0.001
1 millimeter is 1/1 000 of a meter.
Micrometer
µm
um
1E-6
1 micrometer is 1/1 000 of a millimeter.
Nanometer
nm
1E-9
1 nanometer is 1/1 000 of a micrometer.
Mass
1 kilogram
Mass is defined by the kilogram prototype.
See http://physics.nist.gov/cuu/Units/kilogram.html and
http://en.wikipedia.org/wiki/Mass
Kilogram
kg
1
1 kilogram is the reference unit of mass.
Gram
g
1E-3
1 gram is 1/1 000 of a kilogram.
Milligram
mg
1E-6
1 milligram is 1/1 000 of a gram.
Microgram
µg
ug
1E-9
1 mikrogram is 1/1 000 of a milligram.
Time
1 second
Time is defined by the duration of 9 192 631 770 periods of the
radiation corresponding to the transition between the two hyperfine
levels of the ground state of the cesium 133 atom.
See http://physics.nist.gov/cuu/Units/second.html and
http://en.wikipedia.org/wiki/Second
Year
y
year
years
31557600
1 year is 365.25 days in average or 31 557 600 seconds.
Month
mo
month
months
2629800
1 month is 30.4375 days in average or 2 629 800 seconds.
Week
w
week
weeks
604800
1 week is 7 days or 604 800 seconds.
Day
d
day
days
86400
1 day is 24 hours or 86 400 seconds.
Hour
h
hour
hours
3600
1 hour is 60 minutes or 3600 seconds.
Minute
min
minute
minutes
60
1 minute is 60 seconds.
Second
s
sec
1
1 second is the reference unit of time.
Millisecond
ms
1E-3
1 millisecond is 1/1 000 of a second.
Microsecond
µs
ug
1E-6
1 microsecond is 1/1 000 of a millisecond.
Nanosecond
ns
1E-9
1 nanosecond is 1/1 000 of a microsecond.
Temperature
1 kelvin
Temperature is defined as 1/273.16 of the triple point of water.
See http://physics.nist.gov/cuu/Units/kelvin.html and
http://en.wikipedia.org/wiki/Kelvin
Kelvin
K
1
Kelvin is the reference unit of temperature.
Celsius
°C
C
1
273.15
The Celcius scale has 0 = freezing point of water
and 100 = boiling point of water and is related to Kelvin by an
offset of 273.15.
Fahrenheit
°F
F
0.55555555555555555555555555555556
241.15
In the Fahrenheit scale the water freezes as 32 degrees
and boils at 212.
Electric current
1 ampere
The ampere is that constant current which, if maintained in two straight parallel
conductors of infinite length, of negligible circular cross section, and placed 1
meter apart in vacuum, would produce between these conductors a force equal to 2 × 10-7
newton per meter of length. See http://physics.nist.gov/cuu/Units/ampere.html and
http://en.wikipedia.org/wiki/Ampere
Ampere
A
1
1 ampere is the reference unit of electric current.
Milliampere
mA
1E-3
1 milliampere is 1/1 000 of an ampere.
Microampere
µA
uA
1E-6
1 microampere is 1/1 000 of a milliampere.
Nanoampere
nA
1E-9
1 nanoampere is 1/1 000 of a microampere.
Amount of substance
1 mol
The mole is the amount of substance of a system which contains as many elementary
entities as there are atoms in 0.012 kilogram of carbon 12. See
http://physics.nist.gov/cuu/Units/mole.html and
http://en.wikipedia.org/wiki/Mole_(unit)
Kilomole
kmol
1000
1 kilomole is 1000 moles.
Mole
mol
1
1 mole is the reference unit of amount of substance.
Millimole
mmol
1E-3
1 millimole is 1/1 000 of a mole.
Micromole
µmol
1E-6
1 micromole is 1/1 000 of a millimole.
Nanomole
nmol
1E-9
1 nanomole is 1/1 000 of a micromole.
Area
1 m²
1 square meter is defined as the area of a square whose sides measure exactly one metre.
See http://en.wikipedia.org/wiki/Area
Square kilometer
km²
km2
1E6
1 square kilometer is 1 000 000 square meters.
Square meter
m²
m2
1
1 square meter is the reference unit of area.
Square centimeter
cm²
cm2
1E-4
1 square centimeter is 1/10 000 of a square meter.
Square millimeter
mm²
mm2
1E-6
1 square millimeter is 1/1 000 000 of a square meter.
Square micrometer
µm²
um2
1E-12
1 square microimeter is 1/1 000 000 of a square millimeter.
Volume
1 m³
1 cubic meter is the volume a cube whose sides measure exactly 1 meter.
See http://en.wikipedia.org/wiki/Volume
Cubic meter
m³
m3
1
1 cubic meter is the reference unit of volume.
Liter
l
1E-3
1 liter is the 1/1 000 of a cubic meter.
Milliliter
ml
cm³
cm3
1E-6
1 milliliter is 1/1 000 of a liter. A milliliter is equal
to 1 cm³.
Microliter
µl
mm³
mm3
1E-9
1 microliter is 1/1 000 of a milliliter. A microliter is
equal to 1 mm³.
Nanoliter
nl
1E-12
1 nanoliter is 1/1 000 of a microliter.
Picoliter
pl
1E-15
1 picoliter is 1/1 000 of a nanoliter.
Velocity
1 m/s
The volocity is the distance traveled during a specified unit of time.
See http://en.wikipedia.org/wiki/Speed
Meter per second
m/s
1
1 m/s is the reference unit of velocity.
Kilometers per hour
km/h
km/hour
3.6
1 m/s is the same as 3.6 km/hour.
Angle
1 radian
One radian is the angle subtended at the center of a circle by an arc that
is equal in length to the radius of the circle. See
http://en.wikipedia.org/wiki/Radian
Radian
rad
1
1 radian is the reference unit of angle.
Degree
°
deg
0.017453292519943295
1 degree is π/180 radians (≈0.0175).
Minute (angle)
'
2.908882086657216E-4
1' = 1/60°
Second (angle)
"
4.84813681109536E-6
1" = 1/60' = 1/3 600°
Force
1 newton
A force is what causes a mass to accelerate. 1 newton is the force required
to give a mass of one kilogram an acceleration of one meter per second
squared. See http://en.wikipedia.org/wiki/Newton
Kilonewton
kN
1000
1 kilonewton is 1 000 N.
Newton
N
1
1 newton is the reference unit of force.
Millinewton
mN
1E-3
1 millinewton is 1/1 000 N.
Micronewton
µN
1E-6
1 micronewton is 1/1 000 mN.
Frequency
1 hertz
The definition of hertz follows directly from the definition of
a second such that the hyperfine splitting in the ground state of the
caesium 133 atom is exactly 9 192 631 770 hertz.
See http://en.wikipedia.org/wiki/Hertz
Hertz
Hz
1
1 hertz is the reference unit of frequency.
Kilohertz
kHz
1000
1 kilohertz is 1 000 hertz.
Megahertz
MHz
1E6
1 megahertz is 1 000 000 hertz.
Gigahertz
GHz
1E9
1 gigahertz is 1 000 000 000 hertz.
Terahertz
THz
1E12
1 terahertz is 1 000 gigahertz.
Density
1 kg/m³
The density of a material is the mass per unit volumne. See
http://en.wikipedia.org/wiki/Density
Grams per cubic centimeter
g/cm³
g/cm3
g/mL
1000
1 g/cm³ is the is the same as 1 g/mL and is 1 000 kilograms per
cubic metre.
Kilograms per cubic meter
kg/m³
kg/m3
g/L
1
1 kg/m³ is the reference unit of density.
Energy
1 joule
One joule is the work done, or energy expended, by a force of one newton moving one
meter along the direction of the force. See http://en.wikipedia.org/wiki/Joule
Kilowatt hour
kWh
3.6E6
1 kilowatt hour is 3 600 000 joules.
Megajoule
MJ
1E6
1 megajoule is 1 000 000 joules.
Kilojoule
kJ
1E3
1 kilojoule is 1 000 joules.
Joule
J
Ws
1
1 joule is the reference unit of energy. A joule is also
equal to one watt-second (Ws)
Millijoule
mJ
1E-3
1 millijoule is 1/1 000 of a joule.
Mikrojoule
µJ
1E-6
1 microjoule is 1/1 000 of a millijoule.
Megaelectronvolt
MeV
1.60217653E-12
1 kiloelectronvolt is 1 000 000 electronvolts.
Kiloelectronvolt
keV
1.60217653E-15
1 kiloelectronvolt is 1 000 electronvolts.
Electronvolt
eV
1.60217653E-19
1 electronvolt is the amount of kinetic energy gained by a single unbound electron
when it passes through an electrostatic potential difference of one volt, in vacuum.
1 eV ≈ 1.602 176 53E−19 J.
Power
1 watt
Power measures the rate of energy conversion. The reference unit
is 1 watt which is equal to 1 joule of energy per second.
See http://en.wikipedia.org/wiki/Watt
Megawatt
MW
MJ/s
1E6
1 megawatt is 1 000 000 watts.
Kilowatt
kW
kJ/s
1000
1 kilowatt is 1 000 watts.
Watt
W
J/s
1.0
1 watt is the reference unit of power.
Milliwatt
mW
mJ/s
1E-3
1 milliwatt is 1/1 000 watt.
Microwatt
µW
uW
µJ/s
1E-3
1 microwatt is 1/1 000 milliwatt.
Pressure
1 pascal
Pressure is a measure of perpendicular force per unit area i.e. equivalent
to one newton per square meter. See http://en.wikipedia.org/wiki/Pascal_(unit)
Megapascal
MPa
MN/m²
MN/m2
1E6
1 megapascal is 1 000 000 Pa.
Kilopascal
kPa
kN/m²
kN/m2
1000
1 kilopascal is 1 000 Pa.
Pascal
Pa
N/m²
N/m2
1.0
1 pascal is the reference unit of pressure.
Millipascal
mPa
mN/m²
mN/m2
1E-3
1 millipascal is 1/1 000 of a pascal.
Micropascal
µPa
uPa
µN/m²
uN/m2
1E-6
1 micropascal is 1/1 000 of a millipascal.
Electric potential
1 volt
The volt is defined as the potential difference across a conductor
when a current of one ampere dissipates one watt of power. See
http://en.wikipedia.org/wiki/Volt
Kilovolt
kV
1000
1 kilovolt is 1 000 volts.
Volt
V
1
1 volt is the reference unit of electrical potential.
Millivolt
mV
1E-3
1 millivolt is 1/1 000 of a volt.
Microvolt
µV
uV
1E-6
1 microvolt is 1/1 000 of a millivolt.
Electric resistance
1 ohm
The ohm is the electric resistance between two points of a conductor when
a constant potential difference of 1 volt, applied to these points, produces
in the conductor a current of 1 ampere.
See http://en.wikipedia.org/wiki/Ohm
Megaohm
MΩ
MO
1E6
1 megaohm is 1 000 000 ohms.
Kiloohm
kΩ
kO
1000
1 kiloohm is 1 000 ohms.
Ohm
Ω
O
1
1 ohm is the reference unit of electrical resistance.
Milliohm
mΩ
mO
1E-3
1 milliohm is 1/1 000 ohm.
Electrical charge
1 coulomb
1 coulomb is the amount of electric charge transported by a current of 1 ampere in 1 second.
See http://en.wikipedia.org/wiki/Coulomb
Ampere-hour
Ah
3600
1 ampere-hour is 3 600 coulombs.
Kilocoulomb
kC
kAs
1000
1 kilocoulomb is 1 000 coulombs.
Coulomb
C
As
1
1 coulomb is the reference unit of charge.
Millicoulomb
mC
mAs
1E-3
1 millicoulomb is 1/1 000 of a coulomb.
Microoulomb
µC
uC
µAs
uAs
1E-6
1 microcoulomb is 1/1 000 of a millicoulomb.
Nanooulomb
nC
nAs
1E-9
1 nanocoulomb is 1/1 000 of a microcoulomb.
Capacitance
1 farad
One farad is the capacitance for which a potential difference of one volt results in
a static charge of one coulomb.
Farad
F
1
1 farad is the reference unit of capacitance.
Millifarad
mF
1E-3
1 millifarad is 1/1 000 of a farad.
Microfarad
µF
uF
1E-6
1 microfarad is 1/1 000 of a millifarad.
Nanofarad
nF
1E-9
1 nanofarad is 1/1 000 of a microfarad.
Picofarad
pF
1E-12
1 picofarad is 1/1 000 of a nanofarad.
Magnetic field
1 tesla
One tesla is equal to one weber per square meter. See
http://en.wikipedia.org/wiki/Tesla_(unit)
Tesla
T
1
1 tesla is the reference unit of magnetic field.
Millitesla
mT
1E-3
1 millitesla is 1/1 000 of a tesla.
Microtesla
µT
uT
1E-6
1 microtesla is 1/1 000 of a millitesla.
Nanotesla
nT
1E-9
1 nanotesla is 1/1 000 of a microtesla.
Magnetic flux
1 weber
One weber is the magnetic flux which, linking a circuit of one turn, would produce
in it an electromotive force of 1 volt if it were reduced to zero at a uniform rate in 1 second.
See http://en.wikipedia.org/wiki/Weber_(unit)
Weber
Wb
1
1 weber is the reference unit of magnetic flux.
Milliweber
mWb
1E-3
1 milliweber is 1/1 000 of a weber.
Microweber
µWb
uWb
1E-6
1 microweber is 1/1 000 of a milliweber.
Nanoweber
nWb
1E-9
1 nanoweber is 1/1 000 of a microweber.
Dose (absorbed)
1 gray
One gray is the absorption of one joule of radiation energy by one kilogram of matter.
See http://en.wikipedia.org/wiki/Gray_(unit) and http://en.wikipedia.org/wiki/Absorbed_dose
Gray
Gy
1
1 gray is the reference unit of absorbed dose.
Milligray
mGy
1E-3
1 milligray is 1/1 000 of a gray.
Microgray
µGy
uGy
1E-6
1 microgray is 1/1 000 of a milligray.
Dose (equivalent)
1 sievert
The equivalent dose attempts to reflect the biological effects of radiation as
opposed to the physical aspects, which are characterised by the absorbed dose.
See http://en.wikipedia.org/wiki/Sievert and http://en.wikipedia.org/wiki/Effective_dose
Sievert
Sv
1
1 sievert is the reference unit of equivalent dose.
Millisievert
mSv
1E-3
1 millisievert is 1/1 000 of a sievert.
Microsievert
µSv
uSv
1E-6
1 microsievert is 1/1 000 of a millisievert.
Radioactivity
1 becquerel
1 Bq is defined as the activity of a quantity of radioactive material in
which one nucleus decays per second. See http://en.wikipedia.org/wiki/Becquerel
Becquerel
Bq
1
1 becquerel is the reference unit of radioactivity.
Kilobecquerel
kBq
1000
1 kilobecquerel is 1 000 becquerels.
Megabecquerel
MBq
1E6
1 megabecquerel is 1 000 000 becquerels.
Gigabecquerel
GBq
1E9
1 gigabecquerel is 1 000 000 000 becquerels.
Fraction
1
Fractions are used to denote relative proportions in
any measured quantity. A fraction is always dimensionless.
See http://en.wikipedia.org/wiki/Parts-per_notation
Percent
%
0.01
1 percent is 1/100 of the whole.
Permille
‰
0.001
1 permille is 1/1 000 of the whole.
Part-per-million
ppm
1E-6
1 part-per-million is 1/1 000 000 of the whole.
Acceleration
1 m/s²
Acceleration is the increase (or decrease) of speed per unit of time.
See http://en.wikipedia.org/wiki/Acceleration
Meters per second squared
m/s²
m/s2
1
1 meter per second squared is the reference unit of acceleration.
Torque
1 Nm
A torque is a pseudo-vector that measures the tendency of a force to rotate
an object about some axis.
See http://en.wikipedia.org/wiki/Torque
Kilonewtonmeter
kNm
1000
1 kilonewtonmeter is 1 000 newtonmeters.
Newtonmeter
Nm
1
1 newtonmeter is the reference unit of torque.
Millinewtonmeter
mNm
1E-3
1 millinewtonmeter is 1/1 000 of a newtonmeter.
Micronewtonmeter
µNm
uMn
1E-6
1 micronewtonmeter is 1/1 000 of a millinewtonmeter.
Momentum
1 kg·m/s
In classical mechanics, momentum is the product of the mass and velocity of an object.
See http://en.wikipedia.org/wiki/Momentum
Kilogram-meter per second
kgm/s
Ns
1
1 kilogram-meter per second is the reference unit of momentum.
Flow rate
1 m³/s
The flow rate is the volume that passes through a given surface per unit
of time. See http://en.wikipedia.org/wiki/Volumetric_flow_rate
Cubic meter per second
m³/s
m3/s
1
1 cubic meter per second is the reference unit of flow rate.
Liter per second
L/s
1E-3
1 liter per second is 1/1 000 of a cubic meter per second.
Milliliter per second
mL/s
cm³/s
cm3/s
1E-6
1 milliliter per second is 1/1 000 of a liter per second.
Microliter per second
µL/s
uL/s
mm³/s
mm3/s
1E-9
1 milliliter per second is 1/1 000 of a liter per second.
Thermal conductivity
1 W/(m·K)
Thermal conductivity is the property of a material that indicates its ability
to conduct heat. See http://en.wikipedia.org/wiki/Thermal_conductivity.
Watt per meter and Kelvin
W/m·K
W/m K
1
1 watt per meter and Kelvin is the reference unit of thermal conductivity.
Storage size
1 byte
A byte is the basic unit of for measuring storage
requirements for files, etc. We use the binary meaning
of the prefixes kilo (k), mega (M) and giga (G). Eg. 1
kilobyte = 1 024 bytes.
Byte
B
bytes
1
1 byte is the reference unit of file size.
Kilobyte
kB
1024
1 kilobyte is 1 024 bytes.
Megabyte
MB
1048576
1 megabyte is 1 048 576 bytes.
Gigabyte
GB
1073741824
1 gigabyte is 1 073 741 824 bytes.