Wikidata:Requests for comment/Dimensions and units for the quantity datatype

An editor has requested the community to provide input on "Dimensions and units for the quantity datatype" via the Requests for comment (RFC) process. This is the discussion page regarding the issue.

If you have an opinion regarding this issue, feel free to comment below. Thank you!

THIS RFC IS CLOSED. Please do NOT vote nor add comments.

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

Stale discussion now. Feedback forwarded to Lydia in this state. Thanks, John F. Lewis (talk) 16:42, 27 April 2014 (UTC)

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The Wikidata development team is working on the implementation of the quantity datatype (Bugzilla: 54318). During this office hour (13.Nov.2013) it was announced that:

• Unit conversion will be configurable, but not defined on-wiki. It will draw upon w:GNU Units (see conversion table here) for reference.
• Most probably dimensions (length, speed, etc) will be associated with properties on creation with a configurable default unit (meter, km/h, etc). When setting a value, another unit of the same dimension can be selected.
• On the client wikis, it will (eventually) be possible to specify a unit for display, with the software taking care of the appropriate conversion.
• Feedback is appreciated on which dimensions and units should be implemented first, and also to detect special cases/needs..

Below there are the dimensions mentioned on "Conversion of units". The list of properties with dimension awaiting creation also should be integrated into this list. If you think that we should use or not use any of them, leave a comment.

Comments

See talk page

Selection of dimensions for testing

SI Prefixes

Metric prefixes

Prefix Symbol 1000m 10n Decimal English word Since yotta Y  10008  1024 1000000000000000000000000 septillion 1991 zetta Z  10007  1021 1000000000000000000000 sextillion 1991 exa E  10006  1018 1000000000000000000 quintillion 1975 peta P  10005  1015 1000000000000000 quadrillion 1975 tera T  10004  1012 1000000000000 trillion 1960 giga G  10003  109 1000000000 billion 1960 mega M  10002  106 1000000 million 1960 kilo k  10001  103 1000 thousand 1795 hecto h  10002/3  102 100 hundred 1795 deca da  10001/3  101 10 ten 1795  10000  100 1 one – deci d  1000−1/3  10−1 0.1 tenth 1795 centi c  1000−2/3   10−2 0.01 hundredth 1795 milli m  1000−1  10−3 0.001 thousandth 1795 micro µ  1000−2  10−6 0.000001 millionth 1960 nano n  1000−3  10−9 0.000000001 billionth 1960 pico p  1000−4  10−12 0.000000000001 trillionth 1960 femto f  1000−5  10−15 0.000000000000001 quadrillionth 1964 atto a  1000−6  10−18 0.000000000000000001 quintillionth 1964 zepto z  1000−7  10−21 0.000000000000000000001 sextillionth 1991 yocto y  1000−8  10−24 0.000000000000000000000001 septillionth 1991

Length

Category:Units of length (Q8794341) -- unit of length (Q1978718)

metric system (Q232405) of length (Q36253)

Name of unit	Symbol	Definition	Relation to SI units
kilometre (Q828224)	km		≡ 1000 m
metre (Q11573) (SI base unit (Q223662))	m	≡ Distance light travels in 1⁄299792458 of a second in vacuum. ≈ 1⁄10000000 of the distance from equator to pole.	≡ 1 m
centimetre (Q174728)	cm		≡ 0.01 m
millimetre (Q174789)	mm		≡ 0.001 m
micrometre (Q175821)	µm		≡ 1×10−6 m
nanometre (Q178674)	nm		≡ 1×10−9 m
picometre (Q192274)	pm		≡ 1×10−12 m
femtometre (Q208788)	fm		≡ 1×10−15 m
attometre (Q6003257)	am		≡ 1×10−18 m

Area

Category:Units of area (Q4393754)

metric system (Q232405) of area (Q11500)

Name of unit	Symbol	Definition	Relation to SI units
square kilometre (Q712226)	km2	≡ 1 km × 1 km	= 106 m2
hectare (Q35852)	ha	≡ 10 000 m2	≡ 10 000 m2
are (Q185078)	a	≡ 100 m2	= 100 m2
square metre (Q25343) (SI unit)	m2	≡ 1 m × 1 m	= 1 m2
square centimetre (Q2489298)	cm2
square millimetre (Q2737347)	mm2
square micrometre	µm2
square nanometre	nm2
square picometre	pm2

Mass

Category:Units of mass (Q7163187)

metric system (Q232405) of mass (Q11423)

Name of unit	Symbol	Definition	Relation to SI units
tonne (Q191118)	t	≡ 1 000 kg	= 1 000 kg
kilogram (Q11570)	kg	≡ mass of the prototype near Paris (≈ mass of 1L of water)	≡ 1 kg
gram (Q41803)	g	≡	= 1×10−3 kg
milligram (Q3241121)	mg	≡	= 1×10−6 kg
microgram (Q1645498)	µg	≡	= 1×10−9 kg

Dimensions and units

Spatial dimensions

Length

Category:Units of length (Q8794341) -- unit of length (Q1978718)

metric system (Q232405) of length (Q36253)

Name of unit	Symbol	Definition	Relation to SI units
kilometre (Q828224)	km		≡ 1000 m
metre (Q11573) (SI base unit (Q223662))	m	≡ Distance light travels in 1⁄299792458 of a second in vacuum. ≈ 1⁄10000000 of the distance from equator to pole.	≡ 1 m
centimetre (Q174728)	cm		≡ 0.01 m
millimetre (Q174789)	mm		≡ 0.001 m
micrometre (Q175821)	µm		≡ 1×10−6 m
nanometre (Q178674)	nm		≡ 1×10−9 m
picometre (Q192274)	pm		≡ 1×10−12 m
femtometre (Q208788)	fm		≡ 1×10−15 m
attometre (Q6003257)	am		≡ 1×10−18 m

Other units of length (Q36253)

Name of unit	Symbol	Definition	Relation to SI units
ångström (Q81454)	Å	≡ 1×10−10 m	≡ 0.1 nm
astronomical unit (Q1811)	AU	≡ 149597870700 m ≈ Distance from Earth to Sun	≡ 149597870700 m
atomic unit of length	a0	≡ Bohr radius (Q652571) of hydrogen	≈ 5.2917720859×10−11 ± 3.6×10−20 m
foot (Q3710) (International)	ft	≡ 0.3048 m ≡ 1/3 yd ≡ 12 inches	≡ 0.3048 m
inch (Q218593) (International)	in	≡ 2.54 cm ≡ 1/36 yd ≡ 1/12 ft	≡ .0254 m
light-year (Q531)	ly	≡ Distance light travels in vacuum in 365.25 days	= 9.4607304725808×1015 m
thousandth of an inch (Q1165799)	mil	≡ 1×10−3 in	≡ 2.54×10−5 m
mile (Q253276) (international)	mi	≡ 80 chains ≡ 5280 ft ≡ 1760 yd	≡ 1609.344 m
nautical mile (Q93318) (international)	NM; nmi	≡ 1852 m	≡ 1852 m
parsec (Q12129)	pc	Distance of star with parallax shift of one arc second from a base of one astronomical unit	≈ 3.085 677 82×1016 ± 6×106 m
yard (Q482798) (International)	yd	≡ 0.9144 m ≡ 3 ft ≡ 36 in	≡ 0.9144 m

For all units including historical or marginal use, see: w:Conversion of units#Length

Area

Category:Units of area (Q4393754)

metric system (Q232405) of area (Q11500)

Name of unit	Symbol	Definition	Relation to SI units
square kilometre (Q712226)	km2	≡ 1 km × 1 km	= 106 m2
hectare (Q35852)	ha	≡ 10 000 m2	≡ 10 000 m2
are (Q185078)	a	≡ 100 m2	= 100 m2
square metre (Q25343) (SI unit)	m2	≡ 1 m × 1 m	= 1 m2
square centimetre (Q2489298)	cm2
square millimetre (Q2737347)	mm2
square micrometre	µm2
square nanometre	nm2
square picometre	pm2

Other units of area (Q11500)

Name of unit	Symbol	Definition	Relation to SI units
acre (Q81292) (international)	ac	≡ 1 ch × 10 ch = 4840 sq yd	≡ 4 046.856 4224 m2
barn (Q209351)	b	≡ 10−28 m2	= 10−28 m2
circular mil (Q5121670); circular thou	circ mil	≡ π/4 mil2	≈ 5.067 075×10−10 m2
square foot (Q857027)	sq ft	≡ 1 ft × 1 ft	≡ 9.290 304×10−2 m2
square inch (Q1063786)	sq in	≡ 1 in × 1 in	≡ 6.4516×10−4 m2
square mil (Q3809228); square thou	sq mil	≡ 1 mil × 1 mil	= 6.4516×10−10 m2
square mile (Q232291) (International)	sq mi	≡ 1 mi × 1 mi	= 2.589 988 110 336×106 m2
square yard (Q1550511) (International)	sq yd	≡ 1 yd × 1 yd	≡ 0.836 127 36 m2

For all units including historical or marginal use, see: w:Conversion of units#Area

Volume

Category:Units of volume (Q7163188)

metric system (Q232405) of volume (Q39297)

Name of unit	Symbol	Definition	Relation to SI units
cubic kilometre (Q4243638)	km3	≡ 1 km3	= 1×109 m3
cubic hectometre	hm3	≡ 1 hm3	= 1×106 m3
cubic metre (Q25517) (SI unit)	m3	≡ 1 m × 1 m × 1 m	≡ 1 m3
litre (Q11582)	L	≡ 1 dm3	≡ 0.001 m3
cubic centimetre (Q1022113) / millilitre	cm3 / cc / ml	≡ 1 cm3	= 1×10−6 m3
cubic millimetre / microlitre / lambda	mm3 / µL / λ	≡ 1 mm3	= 1×10−9 m3

Other units of volume (Q39297)

Name of unit	Symbol	Definition	Relation to SI units
cubic foot (Q1545979)	cu ft	≡ 1 ft × 1 ft × 1 ft	≡ 0.028 316 846 592 m3
cubic inch (Q2140397)	cu in	≡ 1 in × 1 in × 1 in	≡ 16.387 064×10−6 m3
cubic mile (Q1790908)	cu mi	≡ 1 mi × 1 mi × 1 mi	≡ 4 168 181 825.440 579 584 m3
cubic yard (Q2165290)	cu yd	≡ 27 cu ft	≡ 0.764 554 857 984 m3
gallon (Q178413) (imperial)	gal (imp)	≡ 4.546  09 L	≡ 4.546 09×10−3 m3
fluid ounce (Q420266) (fluid imperial)	fl oz (imp)	≡ 1/160 gal (imp)	≡ 28.413 0625×10−6 m3

For all units including historical or marginal use, see: w:Conversion of units#Volume

Plane angle

Category:Units of angle (Q9198409)

metric system (Q232405) of angle (Q11352)

Name of unit	Symbol	Definition	Relation to SI units
radian (Q33680) (SI unit)	rad	The angle subtended at the center of a circle by an arc whose length is equal to the circle's radius. One full revolution encompasses 2π radians.	= 1 rad
milliradian	mrad		≡ 1×10−3 rad
microradian	μrad		≡ 1×10−6 rad
nanoradian	nrad		≡ 1×10−9 rad
picoradian	prad		≡ 1×10−12 rad

angle (Q11352)

Name of unit	Symbol	Definition	Relation to SI units
milliradian (Q1065153) (NATO)		≡ 2π/6400 rad	≈ 0.981 748×10−3 rad
arcminute; arcminute (Q209426)	arcmin, amin, am, ${\hat {'}}$, MOA, ( m )	≡ 1°/60	≈ 0.290 888×10−3 rad
arcsecond; arcsecond (Q829073)	arcsec, asec, as, ( s )	≡ 1°/3600	≈ 4.848 137×10−6 rad
milliarcsecond	mas	≡ 1⁄1,000 arcsecond	≈ 4.8481368 nrad
microarcsecond	μas	≡ 10−6 arcsecond	≈ 4.8481368 prad
degree (Q28390)	°	≡ 1/360 of a revolution ≡ π/180 rad	≈ 17.453 293×10−3 rad
gradian (Q208528); gradian; gon	grad	≡ 1/400 of a revolution ≡ 2π/400 rad ≡ 0.9°	≈ 15.707 963×10−3 rad
hour angle (Q734439)	( h )	≡ 15°	≡ π⁄12 rad
turn (Q304479)	rev / rot	≡ 1 revolution ≡ 2π rad	≡ 2π rad

• NOTE: degrees-minutes-seconds and hours-minutes-seconds (astronomy) are sometimes combined to represent a value.
• For all units including historical or marginal use, see: w:Conversion of units#Plane angle

Solid angle

solid angle (Q208476)

Name of unit	Symbol	Definition	Relation to SI units
millisteradian	msr		= 0.001 sr
square degree (Q254532)	deg²; sq.deg.; (°)²	≡ (π/180)² sr	≈ 0.30462×10−3 sr
steradian (Q177612) (SI unit)	sr	The solid angle subtended at the center of a sphere of radius r by a portion of the surface of the sphere having an area r2. A sphere encompasses 4π sr.	= 1 sr

For all units including historical or marginal use, see: w:Conversion of units#Solid angle

Matter

Mass

Category:Units of mass (Q7163187)

metric system (Q232405) of mass (Q11423)

Name of unit	Symbol	Definition	Relation to SI units
tonne (Q191118)	t	≡ 1 000 kg	= 1 000 kg
kilogram (Q11570)	kg	≡ mass of the prototype near Paris (≈ mass of 1L of water)	≡ 1 kg
gram (Q41803)	g	≡	= 1×10−3 kg
milligram (Q3241121)	mg	≡	= 1×10−6 kg
microgram (Q1645498)	µg	≡	= 1×10−9 kg

Other units of mass (Q11423)

Name of unit	Symbol	Definition	Relation to SI units
dalton (Q483261)	u; AMU; Da		≈ 1.660 538 73×10−27 ± 1.3×10−36 kg
atomic unit of mass, electron rest mass	me		≈ 9.109 382 15×10−31 ± 45×10−39 kg
carat (Q261247) (metric)	ct	≡ 200 mg	= 200 mg
Earth mass (Q681996)	${\begin{smallmatrix}M_{\oplus }\end{smallmatrix}}$		= 5.97219×1024 kg
electronvolt (Q83327)	eV	≡ 1 eV (energy unit) / c2	= 1.7826×10−36 kg
ounce (Q48013)	oz av	≡ 1/16 lb	= 28.349 523 125 g
pound (Q100995)	lb av	≡ 0.453 592 37 kg = 7000 grains	≡ 0.453 592 37 kg
solar mass (Q180892)	S / ${\begin{smallmatrix}M_{\odot }\end{smallmatrix}}$		1.98855 ± 0.00025×1030 kg

For all units including historical or marginal use, see: w:Conversion of units#Mass

Density

Category:Units of density (Q7210922)

mass density (Q29539)

Name of unit	Symbol	Definition	Relation to SI units
metric tons per cubic metre	t/m3	≡ t/m3	= 1,000 kg/m3
kilogram per cubic metre (SI unit)	kg/m3	≡ kg/m3	= 1 kg/m3
gram per cubic metre	g/m3	≡ t/m3	= 0.001 kg/m3
kilogram per litre	kg/L	≡ kg/L	=
gram per millilitre	g/mL	≡ g/mL	=

other units of mass density (Q29539)

Name of unit	Symbol	Definition	Relation to SI units
ounce (avoirdupois) per cubic foot	oz/ft3	≡ oz/ft3	≈ 1.001153961 kg/m3
ounce (avoirdupois) per cubic inch	oz/in3	≡ oz/in3	≈ 1.729994044×103 kg/m3
ounce (avoirdupois) per gallon (imperial)	oz/gal	≡ oz/gal	≈ 6.236023291 kg/m3
pound (avoirdupois) per cubic foot	lb/ft3	≡ lb/ft3	≈ 16.01846337 kg/m3
pound (avoirdupois) per cubic inch	lb/in3	≡ lb/in3	≈ 2.767990471×104 kg/m3
pound (avoirdupois) per gallon (imperial)	lb/gal	≡ lb/gal	≈ 99.77637266 kg/m3

For all units including historical or marginal use, see: w:Conversion of units#Density

Time

Category:Units of time (Q8878351)

SI base unit (Q223662) of time (Q11471)

Name of unit	Symbol	Definition	Relation to SI units
second (Q11574)	s	time of 9 192 631 770 periods of the radiation corresponding to the transition between the 2 hyperfine levels of the ground state of the caesium 133 atom at 0 K (but other seconds are sometimes used in astronomy). Also that time it takes for light to travel a distance of 299,792,458 meters.	(SI base unit)
millisecond (Q723733)	ms
microsecond (Q842015)	µs
nanosecond (Q838801)	ns
picosecond (Q3902709)	ps
femtosecond (Q1777507)	fs
attosecond (Q2483628)	as

Second-derived units of time (Q11471)

Name of unit	Symbol	Definition	Relation to SI units
millennium (Q36507) (1000 Julian years)		≡ 1 000 a (see below for definition of year length)	= 1000 years
century (Q578) (100 Julian years)	c	≡ 100 a (see below for definition of year length)	= 100 years
decade (Q39911) (10 Julian years)	dec	≡ 10 a (see below for definition of year length)	= 10 years
Julian year (Q217208)	a, y, or yr	= 365.25 d average, calculated from common years (365 d) plus one leap year (366 d) every four years	= 31 557 600 s
month (Q5151) (30 SI days)	mo	≡ 30 d	= 2 592 000 s
week (Q23387) (7 SI days)	wk	≡ 7 d	= 168 h = 10 080 min = 604 800 s
day (Q573) (24 SI-derived hours)	d	= 24 h	= 1440 min = 86400 s
hour (Q25235) (60 SI-derived minutes)	h	≡ 60 min	= 3 600 s
minute (Q7727) (60 seconds)	min	≡ 60 s	= 60 s

other units of time

Name of unit	Symbol	Definition	Relation to SI units
atomic unit of time	au	≡ a0/(α·c)	≈ 2.418 884 254×10−17 s
Planck time (Q202642)		≡ (G ℏ/c5)½	≈ 1.351 211 868×10−43 s
svedberg (Q1472674)	S	≡ 10−13 s	= 100 fs

• NOTE: sometimes year-month-day-hours, etc. are combined into a single representation.

Frequency / angular frequency / rotational speed

frequency (Q11652) (metric system (Q232405) )

Name of unit	Symbol	Definition	Relation to SI units
terahertz (Q13548586)	THz		= 1012 Hz
gigahertz (Q3276763)	GHz		= 109 Hz
megahertz (Q732707)	MHz		= 106 Hz
kilohertz (Q2143992)	kHz		= 103 Hz
hertz (Q39369) (SI unit)	Hz	≡ Number of cycles per second	= 1 Hz = 1/s

frequency (Q11652) (as angular frequency (Q834020))

Name of unit	Symbol	Definition	Relation to SI units
radian per second (Q1063756)	rad·s−1, rad/s	≡ One unit rpm equals one rotation completed around a fixed axis in one minute of time.	2π rad/sec = 1 Hz
milliradian per second	mrad·s−1, mrad/s
microradian per second	μrad·s−1, μrad/s
nanoradian per second	nrad·s−1, nrad/s
arcsecond per year	arcsec·y−1
milliarcsecond per year	mas·y−1

frequency (Q11652) (other)

Name of unit	Symbol	Definition	Relation to SI units
revolutions per minute (Q206037)	rpm	≡ One unit rpm equals one rotation completed around a fixed axis in one minute of time.	≈ 0.104719755 rad/s

Mechanics

Speed or velocity

Category:Units of velocity (Q7210890)

velocity (Q11465)

Name of unit	Symbol	Definition	Relation to SI units
foot per hour	fph	≡ 1 ft/h	≈ 8.466 667×10−5 m/s
foot per minute	fpm	≡ 1 ft/min	= 5.08×10−3 m/s
foot per second	fps	≡ 1 ft/s	= 3.048×10−1 m/s
furlong per fortnight		≡ furlong/fortnight	≈ 1.663 095×10−4 m/s
inch per hour	iph	≡ 1 in/hr	≈ 7.05 556×10−6 m/s
inch per minute	ipm	≡ 1 in/min	≈ 4.23 333×10−4 m/s
inch per second	ips	≡ 1 in/s	= 2.54×10−2 m/s
kilometre per hour (Q180154)	km/h	≡ 1 km/h	= 1/3.6 m/s ≈ 2.777 778×10−1 m/s
kilometre per second (Q4220561)	km/s	≡ 3600 km/h	= 1000 m/s ≈ 2777.778×10−1 m/s
knot (Q128822)	kn	≡ 1 nmi/h = 1.852 km/h	≈ 0.514 444 m/s
knot (Admiralty)	kn	≡ 1 NM (Adm)/h = 1.853 184 km/h	= 0.514 773 m/s
Mach number (Q160669)	M	Ratio of the speed to the speed of sound in the medium. Varies especially with temperature. About 1225 km/h (761 mph) in air at sea level to about 1062 km/h (660 mph) at jet altitudes (Template:Convert). Unitless	≈ 340 to 295 m/s for aircraft
metre per second (Q182429) (SI unit)	m/s	≡ 1 m/s	= 1 m/s
mile per hour	mph	≡ 1 mi/h	= 0.447 04 m/s
mile per minute	mpm	≡ 1 mi/min	= 26.8224 m/s
mile per second	mps	≡ 1 mi/s	= 1 609.344 m/s
speed of light in vacuum (Q2111) in vacuum	c	≡ 299 792 458 m/s	= 299 792 458 m/s
speed of sound (Q124003) in air	s	Varies especially with temperature. About 1225 km/h (761 mph) in air at sea level to about 1062 km/h (660 mph) at jet altitudes.	≈ 340 to 295 m/s at aircraft altitudes

A velocity consists of a speed combined with a direction; the speed part of the velocity takes units of speed.

Acceleration

Category:Units of acceleration (Q6456385)

acceleration (Q11376)

Name of unit	Symbol	Definition	Relation to SI units
foot per hour per second	fph/s	≡ 1 ft/(h·s)	≈ 8.466 667×10−5 m/s2
foot per minute per second	fpm/s	≡ 1 ft/(min·s)	= 5.08×10−3 m/s2
foot per second squared	fps2	≡ 1 ft/s2	= 3.048×10−1 m/s2
gal; galileo	Gal	≡ 1 cm/s2	= 10−2 m/s2
inch per minute per second	ipm/s	≡ 1 in/(min·s)	≈ 4.233 333×10−4 m/s2
inch per second squared	ips2	≡ 1 in/s2	= 2.54×10−2 m/s2
knot per second	kn/s	≡ 1 kn/s	≈ 5.144 444×10−1 m/s2
metres per second squared (Q1051665) (SI unit)	m/s2	≡ 1 m/s2	= 1 m/s2
mile per hour per second	mph/s	≡ 1 mi/(h·s)	= 4.4704×10−1 m/s2
mile per minute per second	mpm/s	≡ 1 mi/(min·s)	= 26.8224 m/s2
mile per second squared	mps2	≡ 1 mi/s2	= 1.609 344×103 m/s2
gravity of Earth (Q673166)	g	≡ 9.806 65 m/s2	= 9.806 65 m/s2

Momentum

momentum (Q41273)

Name of unit	Symbol	Definition	Relation to SI units
kilogram - meter per second	kg m/s		SI unit ≡ kg m/s ≡ N s

Force

Category:Units of force (Q7210873)

force (Q11402)

Name of unit	Symbol	Definition	Relation to SI units
atomic unit of force		≡ me·α2·c2/a0	≈ 8.238 722 06×10−8 N
dyne (Q201933) (cgs unit)	dyn	≡ g·cm/s2	= 10−5 N
kilogram-force (Q216880) ; kilopond; grave-force	kgf; kp; Gf	≡ g × 1 kg	= 9.806 65 N
kip; kip-force	kip; kipf; klbf	≡ g × 1 000 lb	= 4.448 221 615 2605×103 N
milligrave-force, gravet-force	mGf; gf	≡ 'g' × 1 g	= 9.806 65 mN
newton (Q12438) (SI unit)	N	A force capable of giving a mass of one kg an acceleration of one metre per second, per second.	= 1 N = 1 kg·m/s2
ounce-force	ozf	≡ g × 1 oz	= 0.278 013 850 953 7812 N
pound-force	lbf	≡ g × 1 lb	= 4.448 221 615 2605 N
poundal	pdl	≡ 1 lb·ft/s2	= 0.138 254 954 376 N
sthène (Q1793863) (mts unit)	sn	≡ 1 t·m/s2	= 1×103 N
ton-force	tnf	≡ g × 1 sh tn	= 8.896 443 230 521×103 N

See also: Conversion between weight (force) and mass

Pressure or mechanical stress

Category:Units of pressure (Q8890165)

pressure (Q39552) or mechanical stress (Q206175)

Name of unit	Symbol	Definition	Relation to SI units
standard atmosphere (Q177974) (standard)	atm		≡ 101 325 Pa
technical atmosphere (Q909066)	at	≡ 1 kgf/cm2	= 9.806 65×104 Pa
bar (Q103510)	bar		≡ 105 Pa
barye (Q809678)(cgs unit)		≡ 1 dyn/cm2pasca	= 0.1 Pa
centimetre of mercury	cmHg	≡ 13 595.1 kg/m3 × 1 cm × g	≈ 1.333 22×103 Pa
centimetre of water (4 °C)	cmH2O	≈ 999.972 kg/m3 × 1 cm × g	≈ 98.063 8 Pa
foot of mercury (conventional)	ftHg	≡ 13 595.1 kg/m3 × 1 ft × g	≈ 40.636 66×103 Pa
foot of water (39.2 °F)	ftH2O	≈ 999.972 kg/m3 × 1 ft × g	≈ 2.988 98×103 Pa
inch of mercury (conventional)	inHg	≡ 13 595.1 kg/m3 × 1 in × g	≈ 3.386 389×103 Pa
inch of water (39.2 °F)	inH2O	≈ 999.972 kg/m3 × 1 in × g	≈ 249.082 Pa
kilogram-force per square millimetre	kgf/mm2	≡ 1 kgf/mm2	= 9.806 65×106 Pa
kip per square inch	ksi	≡ 1 kipf/sq in	≈ 6.894 757×106 Pa
micron (micrometre) of mercury	$\mu$mHg	≡ 13 595.1 kg/m3 × 1 $\mu$m × g ≈ 0.001 torr	≈ 0.133 322 4 Pa
millimetre of mercury (Q6859652)	mmHg	≡ 13 595.1 kg/m3 × 1 mm × g ≈ 1 torr	≈ 133.3224 Pa
torr (Q185648)	torr	≡ 101 325/760 Pa	≈ 133.3224 Pa
millimetre of water (3.98 °C)	mmH2O	≈ 999.972 kg/m3 × 1 mm × g = 0.999 972 kgf/m2	= 9.806 38 Pa
pascal (Q44395) (SI unit)	Pa	≡ N/m2 = kg/(m·s2)	= 1 Pa
pièze (Q514845) (mts unit)	pz	≡ 1 000 kg/m·s2	= 1×103 Pa = 1 kPa
pound per square foot	psf	≡ 1 lbf/ft2	≈ 47.880 26 Pa
pound per square inch (Q626299)	psi	≡ 1 lbf/in2	≈ 6.894 757×103 Pa
poundal per square foot	pdl/sq ft	≡ 1 pdl/sq ft	≈ 1.488 164 Pa
short ton per square foot		≡ 1 sh tn × g / 1 sq ft	≈ 95.760 518×103 Pa

Torque or moment of force

Category:Units of torque (Q7402026)

torque (Q48103)

Name of unit	Symbol	Definition	Relation to SI units
foot-pound force	ft lbf	≡ g × 1 lb × 1 ft	= 1.355 817 948 331 4004 N·m
foot-poundal (Q5465723)	ft pdl	≡ 1 lb·ft2/s2	= 4.214 011 009 380 48×10−2 N·m
inch-pound force	in lbf	≡ g × 1 lb × 1 in	= 0.112 984 829 027 6167 N·m
metre kilogram	m kg	≡ N × m / g	≈ 0.101 971 621 N·m
newton metre (Q215571) (SI unit)	N·m	≡ N × m = kg·m2/s2	= 1 N·m

Energy

Category:Units of energy (Q7163185)

energy (Q11379)

Name of unit	Symbol	Definition	Relation to SI units
barrel of oil equivalent	boe	≈ 5.8×106 BTU59 °F	≈ 6.12×109 J
British thermal unit (ISO)	BTUISO	≡ 1.0545×103 J	= 1.0545×103 J
British thermal unit (International Table)	BTUIT		= 1.055 055 852 62×103 J
British thermal unit (mean)	BTUmean		≈ 1.055 87×103 J
British thermal unit (thermochemical)	BTUth		≈ 1.054 350×103 J
British thermal unit (39 °F)	BTU39 °F		≈ 1.059 67×103 J
British thermal unit (59 °F)	BTU59 °F	≡ 1.054 804×103 J	= 1.054 804×103 J
British thermal unit (60 °F)	BTU60 °F		≈ 1.054 68×103 J
British thermal unit (63 °F)	BTU63 °F		≈ 1.0546×103 J
calorie (International Table)	calIT	≡ 4.1868 J	= 4.1868 J
calorie (mean)	calmean	1⁄100 of the energy required to warm one gram of air-free water from 0 °C to 100 °C @ 1 atm	≈ 4.190 02 J
calorie (thermochemical)	calth	≡ 4.184 J	= 4.184 J
Calorie (US; FDA)	Cal	≡ 1 kcal	= 1000 cal = 4184 J
calorie (3.98 °C)	cal3.98 °C		≈ 4.2045 J
calorie (15 °C)	cal15 °C	≡ 4.1855 J	= 4.1855 J
calorie (20 °C)	cal20 °C		≈ 4.1819 J
Celsius heat unit (International Table)	CHUIT	≡ 1 BTUIT × 1 K/°R	= 1.899 100 534 716×103 J
cubic centimetre of atmosphere; standard cubic centimetre	cc atm; scc	≡ 1 atm × 1 cm3	= 0.101 325 J
cubic foot of atmosphere; standard cubic foot	cu ft atm; scf	≡ 1 atm × 1 ft3	= 2.869 204 480 9344×103 J
cubic foot of natural gas		≡ 1 000 BTUIT	= 1.055 055 852 62×106 J
cubic yard of atmosphere; standard cubic yard	cu yd atm; scy	≡ 1 atm × 1 yd3	= 77.468 520 985 2288×103 J
electronvolt	eV	≡ e × 1 V	≈ 1.602 177 33×10−19 ± 4.9×10−26 J
erg (cgs unit)	erg	≡ 1 g·cm2/s2	= 10−7 J
foot-pound force	ft lbf	≡ g × 1 lb × 1 ft	= 1.355 817 948 331 4004 J
foot-poundal	ft pdl	≡ 1 lb·ft2/s2	= 4.214 011 009 380 48×10−2 J
gallon-atmosphere (imperial)	imp gal atm	≡ 1 atm × 1 gal (imp)	= 460.632 569 25 J
gallon-atmosphere (US)	US gal atm	≡ 1 atm × 1 gal (US)	= 383.556 849 0138 J
hartree, atomic unit of energy	Eh	≡ me·α2·c2 (= 2 Ry)	≈ 4.359 744×10−18 J
horsepower-hour	hp·h	≡ 1 hp × 1 h	= 2.684 519 537 696 172 792×106 J
inch-pound force	in lbf	≡ g × 1 lb × 1 in	= 0.112 984 829 027 6167 J
joule (Q25269) (SI unit)	J	The work done when a force of one newton moves the point of its application a distance of one metre in the direction of the force.	= 1 J = 1 m·N = 1 kg·m2/s2 = 1 C·V = 1 W·s
kilocalorie; large calorie	kcal; Cal	≡ 1 000 calIT	= 4.1868×103 J
kilowatt-hour; Board of Trade Unit	kW·h; B.O.T.U.	≡ 1 kW × 1 h	= 3.6×106 J
litre-atmosphere	l atm; sl	≡ 1 atm × 1 L	= 101.325 J
quad		≡ 1015 BTUIT	= 1.055 055 852 62×1018 J
rydberg	Ry	≡ R∞·ℎ·c	≈ 2.179 872×10−18 J
therm (E.C.)		≡ 100 000 BTUIT	= 105.505 585 262×106 J
therm (US)		≡ 100 000 BTU59 °F	= 105.4804×106 J
thermie	th	≡ 1 McalIT	= 4.1868×106 J
ton of coal equivalent	TCE	≡ 7 Gcalth	= 29.288×109 J
ton of oil equivalent	TOE	≡ 10 Gcalth	= 41.84×109 J
ton of TNT	tTNT	≡ 1 Gcalth	= 4.184×109 J

Power or heat flow rate

power (Q25342) or heat flow rate (Q12160631)

Name of unit	Symbol	Definition	Relation to SI units
atmosphere-cubic centimetre per minute	atm ccm	≡ 1 atm × 1 cm3/min	= 1.688 75×10−3 W
atmosphere-cubic centimetre per second	atm ccs	≡ 1 atm × 1 cm3/s	= 0.101 325 W
atmosphere-cubic foot per hour	atm cfh	≡ 1 atm × 1 cu ft/h	= 0.797 001 244 704 W
atmosphere-cubic foot per minute	atm·cfm	≡ 1 atm × 1 cu ft/min	= 47.820 074 682 24 W
atmosphere-cubic foot per second	atm cfs	≡ 1 atm × 1 cu ft/s	= 2.869 204 480 9344×103 W
BTU (International Table) per hour	BTUIT/h	≡ 1 BTUIT/h	≈ 0.293 071 W
BTU (International Table) per minute	BTUIT/min	≡ 1 BTUIT/min	≈ 17.584 264 W
BTU (International Table) per second	BTUIT/s	≡ 1 BTUIT/s	= 1.055 055 852 62×103 W
calorie (International Table) per second	calIT/s	≡ 1 calIT/s	= 4.1868 W
erg per second	erg/s	≡ 1 erg/s	= 10−7 W
foot-pound-force per hour	ft lbf/h	≡ 1 ft lbf/h	≈ 3.766 161×10−4 W
foot-pound-force per minute	ft lbf/min	≡ 1 ft lbf/min	= 2.259 696 580 552 334×10−2 W
foot-pound-force per second	ft lbf/s	≡ 1 ft lbf/s	= 1.355 817 948 331 4004 W
horsepower (boiler)	bhp	≈ 34.5 lb/h × 970.3 BTUIT/lb	≈ 9.810 657×103 W
horsepower (European electrical)	hp	≡ 75 kp·m/s	= 736 W
horsepower (imperial electrical)	hp	≡ 746 W	= 746 W
metric horsepower (Q160857) (imperial mechanical)	hp	≡ 550 ft lbf/s	= 745.699 871 582 270 22 W
metric horsepower (Q160857) (metric)	hp	≡ 75 m kgf/s	= 735.498 75 W
litre-atmosphere per minute	L·atm/min	≡ 1 atm × 1 L/min	= 1.688 75 W
litre-atmosphere per second	L·atm/s	≡ 1 atm × 1 L/s	= 101.325 W
lusec	lusec	≡ 1 L·µmHg/s	≈ 1.333×10−4 W
poncelet (Q1768929)	p	≡ 100 m kgf/s	= 980.665 W
square foot equivalent direct radiation	sq ft EDR	≡ 240 BTUIT/h	≈ 70.337 057 W
ton of air conditioning		≡ 2000 lbs of ice melted / 24 h	≈ 3 504 W
ton of refrigeration (imperial)		≡ 2240 lb × iceIT / 24 h: iceIT = 144°F × 2326 J/kg.°F	≈ 3.938 875×103 W
ton of refrigeration (IT)		≡ 200 lbs × iceIT / 24 h: iceIT = 144° × 2326 J/kg.°F	≈ 3.516 853×103 W
watt (Q25236) (SI unit)	W	The power which in one second of time gives rise to one joule of energy.	= 1 W = 1 J/s = 1 N·m/s = 1 kg·m2/s3

Flow (volume)

Flow

Name of unit	Symbol	Definition	Relation to SI units
cubic foot per minute	CFM	≡ 1 ft3/min	= 4.719474432×10−4 m3/s
cubic foot per second	ft3/s	≡ 1 ft3/s	= 0.028316846592 m3/s
cubic inch per minute	in3/min	≡ 1 in3/min	= 2.7311773×10−7 m3/s
cubic inch per second	in3/s	≡ 1 in3/s	= 1.6387064×10−5 m3/s
cubic metre per second (SI unit)	m3/s	≡ 1 m3/s	= 1 m3/s
gallon (US fluid) per day	GPD	≡ 1 gal/d	= 4.381263638×10−8 m3/s
gallon (US fluid) per hour	GPH	≡ 1 gal/h	= 1.051503273×10−6 m3/s
gallon (US fluid) per minute	GPM	≡ 1 gal/min	= 6.30901964×10−5 m3/s
litre per minute	LPM	≡ 1 L/min	= 1.6×10−5 m3/s

Action

Action

Name of unit	Symbol	Definition	Relation to SI units
atomic unit of action	au	≡ ℏ ≡ ℎ/2π	≈ 1.054 571 68×10−34 J·s

Viscosity

Dynamic viscosity

dynamic viscosity (Q15152757) <br\> Category:Units of dynamic viscosity (Q7722695)

Name of unit	Symbol	Definition	Relation to SI units
pascal second (SI unit)	Pa·s	≡ N·s/m2, kg/(m·s)	= 1 Pa·s
poise (Q2100949) (cgs unit)	P	≡ 1 barye·s	= 0.1 Pa·s
pound per foot hour	lb/(ft·h)	≡ 1 lb/(ft·h)	≈ 4.133 789×10−4 Pa·s
pound per foot second	lb/(ft·s)	≡ 1 lb/(ft·s)	≈ 1.488164 Pa·s
pound-force second per square foot	lbf·s/ft2	≡ 1 lbf·s/ft2	≈ 47.88026 Pa·s
pound-force second per square inch	lbf·s/in2	≡ 1 lbf·s/in2	≈ 6,894.757 Pa·s

Kinematic viscosity

kinematic viscosity (Q15106259)

Name of unit	Symbol	Definition	Relation to SI units
square foot per second	ft2/s	≡ 1 ft2/s	= 0.09290304 m2/s
square metre per second (SI unit)	m2/s	≡ 1 m2/s	= 1 m2/s
stokes (Q1569733) (cgs unit)	St	≡ 10−4 m2/s	= 10−4 m2/s

Electromagnetism

Electric current

Electric current

Name of unit	Symbol	Definition	Relation to SI units
ampere (Q25272) (SI base unit)	A	≡ The constant current needed to produce a force of 2 ×10−7 newton per metre between two straight parallel conductors of infinite length and negligible circular cross-section placed one metre apart in a vacuum.	= 1 A = 1 C/s
electromagnetic unit; abampere (cgs unit)	abamp	≡ 10 A	= 10 A
esu per second; statampere (cgs unit)	esu/s	≡ (0.1 A·m/s) / c	≈ 3.335641×10−10 A

Electric charge

Electric charge

Name of unit	Symbol	Definition	Relation to SI units
abcoulomb (Q4176683); electromagnetic unit (cgs unit)	abC; emu	≡ 10 C	= 10 C
atomic unit of charge elementary charge (Q2101)	au	≡ e	≈ 1.602 176 462×10−19 C
coulomb (Q25406)	C	≡ The amount of electricity carried in one second of time by one ampere of current.	= 1 C = 1 A·s
Faraday constant (Q192819)	F	≡ 1 mol × NA·e	≈ 96 485.3383 C
milliampere hour (ampere hour (Q212120))	mA·h	≡ 0.001 A × 1 h	= 3.6 C
statcoulomb (Q21131) or franklin or electrostatic unit (cgs unit)	statC; Fr; esu	≡ (0.1 A·m) / c	≈ 3.335 641×10−10 C

Electric dipole

Electric dipole

Name of unit	Symbol	Definition	Relation to SI units
atomic unit of electric dipole moment	ea0		≈ 8.478 352 81×10−30 C·m
coulomb meter	C·m		= 1 C · 1 m
debye	D	= 10−10 esu·Å	= 3.33564095×10−30 C·m

Electromotive force, electric potential difference

Voltage, electromotive force

Name of unit	Symbol	Definition	Relation to SI units
abvolt (cgs unit)	abV	≡ 1×10−8 V	= 1×10−8 V
statvolt (cgs unit)	statV	≡ c· (1 μJ/A·m)	= 299.792 458 V
volt (SI unit)	V	The difference in electric potential across two points along a conducting wire carrying one ampere of constant current when the power dissipated between the points equals one watt.	= 1 V = 1 W/A = 1 kg·m2/(A·s3)

Electrical resistance

Electrical resistance

Name of unit	Symbol	Definition	Relation to SI units
ohm (Q47083) (SI unit)	Ω	The resistance between two points in a conductor when one volt of electric potential difference, applied to these points, produces one ampere of current in the conductor.	= 1 Ω = 1 V/A = 1 kg·m2/(A2·s3)

Capacitance

capacitance (Q164399) - ability to store electric charge

Name of unit	Symbol	Definition	Relation to SI units
farad (Q131255) (SI unit)	F	The capacitance between two parallel plates that results in one volt of potential difference when charged by one coulomb of electricity.	= 1 F = 1 C/V = 1 A2·s4/(kg·m2)

Inductance

inductance (Q177897)

Name of unit	Symbol	Definition	Relation to SI units
henry (Q163354) (SI unit)	H	The inductance of a closed circuit that produces one volt of electromotive force when the current in the circuit varies at a uniform rate of one ampere per second.	= 1 H = 1 Wb/A = 1 kg·m2/(A·s)2

Magnetic flux

Category:Units of magnetic flux (Q7722730)

magnetic flux (Q177831)

Name of unit	Symbol	Definition	Relation to SI units
maxwell (Q608697) (CGS unit)	Mx	≡ 10−8 Wb	= 1×10−8 Wb
weber (Q170804) (SI unit)	Wb	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.	= 1 Wb = 1 V·s = 1 kg·m2/(A·s2)

Magnetic flux density

Category:Units of magnetic flux density (Q7722737)

What physicists call en:Magnetic field is called Magnetic flux density by electrical engineers and magnetic flux density (Q30204) by applied mathematicians and electrical engineers.

magnetic field (Q11408)

Name of unit	Symbol	Definition	Relation to SI units
gauss (Q177493) (CGS unit)	G	≡ Mx/cm2 = 10−4 T	= 1×10−4 T
tesla (Q163343) (SI unit)	T	≡ Wb/m2	= 1 T = 1 Wb/m2 = 1 kg/(A·s2)

Temperature

Category:Units of temperature (Q7210885)

en:Conversion of units of temperature

temperature (Q11466)

Name of unit	Symbol	Definition	Relation to SI units
degree Celsius (Q25267)	°C	°C ≡ K − 273.15	[K] ≡ [°C] + 273.15
degree Fahrenheit (Q42289)	°F	°F ≡ °C × 9/5 + 32	[K] ≡ ([°F] + 459.67) × 5/9
kelvin (Q11579) (SI base unit)	K	≡ 1/273.16 of the thermodynamic temperature of the triple point of water	≡ 1 K

Information entropy

information entropy (Q204570)

Name of unit	Symbol	Definition	Relation to SI units	Relation to bits
SI unit	J/K	≡ J/K	= 1 J/K
nat; nip; nepit	nat	≡ kB	= 1.380 650 5(23)×10−23 J/K
bit (Q8805) ; shannon	bit; b; Sh	≡ ln(2) × kB	= 9.569 940 (16)×10−24 J/K	= 1 bit
ban; hartley	ban; Hart	≡ ln(10) × kB	= 3.179 065 3(53)×10−23 J/K
nibble		≡ 4 bits	= 3.827 976 0(64)×10−23 J/K	= 22 bit
byte (Q8799)	B	≡ 8 bits	= 7.655 952 (13)×10−23 J/K	= 23 bit
kilobyte (Q79726) (decimal)	kB	≡ 1 000 B	= 7.655 952 (13)×10−20 J/K	= 8×103 bit = 8000 bit
kilobyte (kibibyte)	KB; KiB	≡ 1 024 B	= 7.839 695 (13)×10−20 J/K	= 213 bit = 8192 bit

Often, information entropy is measured in shannons, whereas the (discrete) storage space of digital devices is measured in bits. Thus, uncompressed redundant data occupy more than one bit of storage per shannon of information entropy. The multiples of a bit listed above are usually used with this meaning. Other times the bit is used as a measure of information entropy and is thus a synonym of shannon.

Lighting

Luminous intensity

The candela is the preferred nomenclature for the SI unit.

luminous intensity (Q104831)

Name of unit	Symbol	Definition	Relation to SI units
candela (Q83216) (SI base unit); candle	cd	The luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.	= 1 cd
candlepower (new)	cp	≡ cd The use of candlepower as a unit is discouraged due to its ambiguity.	= 1 cd
candlepower (old, pre-1948)	cp	Varies and is poorly reproducible. Approximately 0.981 cd.	≈ 0.981 cd

Luminance

Category:Units of luminance (Q7722791)

luminance (Q355386)

Name of unit	Symbol	Definition	Relation to SI units
candela per square foot	cd/ft2	≡ cd/ft2	≈ 10.763910417 cd/m2
candela per square inch	cd/in2	≡ cd/in2	≈ 1,550.0031 cd/m2
candela per square metre (SI unit); nit (deprecated) Q281096	cd/m2	≡ cd/m2	= 1 cd/m2
foot-lambert (Q5465726)	fL	≡ (1/π) cd/ft2	≈ 3.4262590996 cd/m2
lambert (Q905912)	L	≡ (104/π) cd/m2	≈ 3,183.0988618 cd/m2
stilb (Q640907) (CGS unit)	sb	≡ 104 cd/m2	≈ 1×104 cd/m2

Luminous flux

Category:Units of luminous flux (Q7722767)

luminous flux (Q107780)

Name of unit	Symbol	Definition	Relation to SI units
lumen (Q484092) (SI unit)	lm	≡ cd·sr	= 1 lm = 1 cd·sr

Illuminance

Category:Units of illuminance (Q7722749)

illuminance (Q194411)

Name of unit	Symbol	Definition	Relation to SI units
footcandle; lumen per square foot	fc	≡ lm/ft2	= 10.763910417 lx
lumen per square inch	lm/in2	≡ lm/in2	≈ 1,550.0031 lx
lux (Q179836) (SI unit)	lx	≡ lm/m2	= 1 lx = 1 lm/m2
phot (Q901492) (CGS unit)	ph	≡ lm/cm2	= 1×104 lx

Radiation

Radiation - source activity

Category:Units of radioactivity (Q7722761)

radioactivity (Q11448)

Name of unit	Symbol	Definition	Relation to SI units
becquerel (Q102573) (SI unit)	Bq	≡ Number of disintegrations per second	= 1 Bq = 1/s
curie (Q229354)	Ci	≡ 3.7×1010 Bq	= 3.7×1010 Bq
rutherford (Q267637) (H)	rd	≡ 1 MBq	= 1×106 Bq

Please note that although becquerel (Bq) and hertz (Hz) both ultimately refer to the same SI base unit (s⁻¹), Hz is used only for periodic phenomena, and Bq is only used for stochastic processes associated with radioactivity.

Radiation - exposure

Category:Units of radiation dose (Q7163135)

exposure (Q336938) (Radiation - exposure)

Name of unit	Symbol	Definition	Relation to SI units
coulomb per kilogram (SI unit)	C/kg		= 1C / 1kg
roentgen (Q321017) (cgs unit)	R	1 R ≡ 2.58×10−4 C/kg	= 2.58×10−4 C/kg

The roentgen is not an SI unit and the NIST strongly discourages its continued use.

Radiation - absorbed dose

Category:Units of radiation dose (Q7163135)

Radiation - absorbed dose (Q215313)

Name of unit	Symbol	Definition	Relation to SI units
gray (Q190095) (SI unit)	Gy	≡ 1 J/kg = 1 m2/s2	= 1 Gy
rad (Q1052397)	rad	≡ 0.01 Gy	= 0.01 Gy

Radiation - equivalent dose

Radiation - dose equivalent (Q256106)

Name of unit	Symbol	Definition	Relation to SI units
Roentgen equivalent man (Q260126)	rem	≡ 0.01 Sv	= 0.01 Sv
sievert (Q103246) (SI unit)	Sv	≡ 1 J/kg	= 1 Sv

Although the definitions for sievert (Sv) and gray (Gy) would seem to indicate that they measure the same quantities, this is not the case. The effect of receiving a certain dose of radiation (given as Gy) is variable and depends on many factors, thus a new unit was needed to denote the biological effectiveness of that dose on the body; this is known as the equivalent dose and is shown in Sv. The general relationship between absorbed dose and equivalent dose can be represented as

H = Q · D

where H is the equivalent dose, D is the absorbed dose, and Q is a dimensionless quality factor. Thus, for any quantity of D measured in Gy, the numerical value for H measured in Sv may be different.

Concentration and chemical composition

Category:Units of chemical measurement (Q8919525)

concentration (Q3686031) and chemical composition (Q1263816)

Name of unit	Symbol	Definition	Relation to SI units
molarity (Q672821) (SI-standard)	mol/m³	1 mol of a substance in one m³
percent (Q11229)	%	percentage
molarity (Q672821) (in liters)	mol/l mol/dm³	1 mol of a substance in one l or dm³	≡ 1000 mol/m³
mass concentration (Q589446) (SI-standard)	kg/m³	1 kg of a substance in one m³
mass concentration (Q589446) (Commonly used in biology)	g/100 ml	1 g of a substance in 100 ml
mass fraction (Q899138) mass ratio (Q1563068)	kg/kg	How many kg of a substance in 1 kg of a mixture/compound/solution/alloy. Commonly µg/g.
volume fraction (Q909482) volume concentration (Q907948) volume percent (Q2080811) ratio of volumes (Q1647035)	dm³/dm³ l/l	How many dm³ or liter of a substance in 1 dm³ or liter total. Or two volumes in relation to each other.
amount-of-substance fraction (Q125264)	mol/mol	How many mol of a substance in proportion to another substance.

• Instead of ppm (and similar ppb, ppt) use the correct dimensions (µg/g, ng/g, µl/l) or for numbers without dimensions 10^-6 (or 10^-4 %). Billion and Trillion are not used the same everywhere and the notation is ambiguous because nobody can readily tell what the basis of the ratio (volume, mass, molar) is. --Tobias1984 (talk) 11:48, 14 November 2013 (UTC)

Thermodynamic units

Category:Units of chemical measurement (Q8919525)

Name of unit	Symbol	Definition	Relation to SI units
Specific enthalpy (Q161064) (SI-standard)	kJ/mol, kJ/kg	energy per (mass or molar unit)
Specific entropy (Q5380792)	kJ/mol K, kJ/kg K	energy per (mass or molar unit) per kelvin
Specific heat capacity (Q179388)	kJ/mol K, kJ/kg K	energy per (mass or molar unit) per kelvin

Sound

Loudness

Name of unit	Symbol	Definition	Relation to SI units
sone (Q676380)	N

Loudness level

Name of unit	Symbol	Definition	Relation to SI units
phon (Q781545)	L_N

Dimensionless units

Percentage

• percent (Q11229), associated symbol: %

Currency

• Unit = currency symbol. With the qualifiers "point in time".--Micru (talk) 11:28, 22 November 2013 (UTC)

Category:Currency (Q6959409)

currency (Q8142)

Name of unit	Symbol	Definition	Relation to SI units
United States dollar (Q4917)	$	US dollar
pound sterling (Q25224)	£	UK pound
euro (Q4916)	€
yen (Q8146)	¥

Notes and references

Notes

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The above discussion is preserved as an archive. Please do not modify it. Subsequent comments should be made in a new section.