Metal weight

Measure­ment units

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SI Base Units

NameSym­bolUnit of
secondstime
metermlength
kilogramkgmass
ampereAelectric current
kelvinKthermodynamic temperature
molemolamount of substance
candelacdluminous intensity


SI Derived Units

Name Sym­bol Unit of Equivalent in Base Units Other Equivalents
becquerel Bq activity referred to a radionuclide 1/s —
coulomb C electric charge A⋅s V ⋅ F = J ∕ V
degree Celsius °C Celsius temperature K temperature in K − 273.15
farad F capacitance A²⋅s⁴/kg⋅m² C ∕ V = A ⋅ s ∕ V
gray Gy absorbed dose, kerma m²/s² J ∕ kg
henry H inductance kg⋅m²/A²⋅s² Wb ∕ A = V ⋅ s ∕ A
hertz Hz frequency 1/s —
joule J energy, work, amount of heat kg⋅m²/s² N ⋅ m = W ⋅ s = Pa ∙ m³
katal kat catalytic activity mol/s —
lumen lm luminous flux cd (4 × π) cd ⋅ sr = lx ⋅ m²
lux lx illuminance cd/m² (4 × π) cd ⋅ sr ∕ m² = lm ∕ m²
newton N force kg⋅m/s² J ∕ m = W ⋅ s ∕ m = Pa ⋅ m²
ohm Ω electric resistance kg⋅m²/A²⋅s³ V ∕ A = 1 ∕ S
pascal Pa pressure, stress kg/m⋅s² N ∕ m² = J ∕ m³
radian rad plane angle 1 (0.5 ∕ π) of a circle ≈ 0.159 154 of a circle ≈ 57.296° ≈ 3 437.746′
siemens S electric conductance A²⋅s³/kg⋅m² A ∕ V = 1 ∕ Ω
sievert Sv dose equivalent m²/s² J ∕ kg
steradian sr solid angle 1 (0.25 ∕ π) of a sphere ≈ 0.079 577 of a sphere
tesla T magnetic flux density kg/A⋅s² Wb ∕ m² = N ∕ A ⋅ m
volt V electric potential difference kg⋅m²/A⋅s³ W ∕ A = J ∕ C = Wb ∕ s
watt W power, radiant flux kg⋅m²/s³ J ∕ s = V ⋅ A = N ⋅ m ∕ s
weber Wb magnetic flux kg⋅m²/A⋅s² V ⋅ s = H ⋅ A = T ⋅ m² = J ∕ A




SI Prefixes

Name Sym­bol Number Base 10 Short Scale Long Scale
quetta Q 1 000 000 000 000 000 000 000 000 000 000 10³⁰ nonillion quintillion
ronna R 1 000 000 000 000 000 000 000 000 000 10²⁷ octillion quadrilliard
yotta Y 1 000 000 000 000 000 000 000 000 10²⁴ septillion quadrillion
zetta Z 1 000 000 000 000 000 000 000 10²¹ sextillion trilliard
exa E 1 000 000 000 000 000 000 10¹⁸ quintillion trillion
peta P 1 000 000 000 000 000 10¹⁵ quadrillion billiard
tera T 1 000 000 000 000 10¹² trillion billion
giga G 1 000 000 000 10⁹ billion milliard
mega M 1 000 000 10⁶ million million
kilo k 1 000 10³ thousand thousand
– – 1 10⁰ one one
milli m 0.001 10⁻³ thousandth thousandth
micro μ 0.000 001 10⁻⁶ millionth millionth
nano n 0.000 000 001 10⁻⁹ billionth milliardth
pico p 0.000 000 000 001 10⁻¹² trillionth billionth
femto f 0.000 000 000 000 001 10⁻¹⁵ quadrillionth billiardth
atto a 0.000 000 000 000 000 001 10⁻¹⁸ quintillionth trillionth
zepto z 0.000 000 000 000 000 000 001 10⁻²¹ sextillionth trilliardth
yocto y 0.000 000 000 000 000 000 000 001 10⁻²⁴ septillionth quadrillionth
ronto r 0.000 000 000 000 000 000 000 000 001 10⁻²⁷ octillionth quadrilliardth
quecto q 0.000 000 000 000 000 000 000 000 000 001 10⁻³⁰ nonillionth quintillionth
SI prefixes which are not multiples or sub-multiples of 1 000
hecto h 100 10² hundred hundred
deca da 10 10¹ ten ten
– – 1 10⁰ one one
deci d 0.1 10⁻¹ tenth tenth
centi c 0.01 10⁻² hundredth hundredth


Prefixes for powers of 2

Name Sym­bol Number Base 2 Short Scale Long Scale
yobi Yi 1 208 925 819 614 629 174 706 176 2⁸⁰ ≈ 1.2 septillion ≈ 1.2 quadrillion
zebi Zi 1 180 591 620 717 411 303 424 2⁷⁰ ≈ 1.2 sextillion ≈ 1.2 trilliard
exbi Ei 1 152 921 504 606 846 976 2⁶⁰ ≈ 1.2 quintillion ≈ 1.2 trillion
pebi Pi 1 125 899 906 842 624 2⁵⁰ ≈ 1.1 quadrillion ≈ 1.1 billiard
tebi Ti 1 099 511 627 776 2⁴⁰ ≈ 1.1 trillion ≈ 1.1 billion
gibi Gi 1 073 741 824 2³⁰ ≈ 1.1 billion ≈ 1.1 milliard
mebi Mi 1 048 576 2²⁰ ≈ 1.0 million ≈ 1.0 million
kibi Ki 1 024 2¹⁰ ≈ 1.0 thousand ≈ 1.0 thousand
– – 1 2⁰ one one




Non-SI units accepted for use with the SI

Name Sym­bol Unit of Equivalent in SI Units Other Equivalents
minute min time 60 s 1 ∕ 1 440 d = 1 ∕ 60 h
hour h time 3 600 s 1 ∕ 24 d = 60 min
day d time 86 400 s 24 h = 1 440 min
degree of arc ° plane angle, phase angle (π ∕ 180) rad 60′ = 3 600″ = 1 ∕ 360 of a circle ≈ 0.017 453 293 rad
minute of arc ′ plane angle, phase angle (π ∕ 10 800) rad 1 ∕ 60° = 60″ = 1 ∕ 21 600 of a circle ≈ 290.888 209 μrad
second of arc ″ plane angle, phase angle (π ∕ 648 000) rad 1 ∕ 3 600° = 1 ∕ 60′ = 1 ∕ 1 296 000 of a circle ≈ 4.848 137 μrad
liter l, L volume 0.001 m³ 1 000 000 mm³ = 1 000 cm³ = 10 cm × 10 cm × 10 cm
tonne t mass 1 000 kg 1 Mg = 1 000 000 g
hectare ha area 10 000 m² 0.01 km² = 100 m × 100 m
bel B logarithmic ratio quantities 1 0.5 × (ln 10) Np ≈ 1.151 292 Np
neper Np logarithmic ratio quantities 1 2 ∕ (ln 10) B ≈ 0.868 588 B
electronvolt eV energy 160.217 663 4 × 10⁻²¹ J ≈ 160.218 zJ
dalton Da mass ≈ 1.660 539 04 × 10⁻²⁷ kg ≈ 1.660 539 yg
astronomical unit au length 149.597 870 7 × 10⁹ m 149.597 870 7 Gm

The dalton used to be called unified atomic mass unit [u]. The astronomical unit used to have the symbol ua.
The gal [Gal] is an unit of acceleration, equalling 0.01 m/s, 1 cm/s or 0.036 km/h.




Other important units

NameSym­bolUnit ofEquivalent
yearatime≈ 365.25 d
month–time≈ 30.44 d
week–time7 d
bitbitdigital information–
byteBdigital information8 bit



Additional units permitted in the European Union 🇪🇺

NameSym­bolUnit ofEquivalent
barbarpressure, stress100 000 Pa = 100 kPa
revolution–plane angle(2 × π) rad = 360° = 1 ∕ 1 of a circle ≈ 6.283 185 rad
grade, gon gonplane angle(π ∕ 200) rad = 0.9° = 1 ∕ 400 of a circle ≈ 0.015 708 rad
dioptre–vergency of optical systems1 ∕ m
metric carat–mass of precious stones0.000 2 kg = 0.2 g = 200 mg
areaarea of farmland and building land100 m² = 0.01 ha = 10 m × 10 m
textexmass per unit length of textile yarns and threads0.000 001 kg ∕ m = 1 μg ∕ m = 1 g ∕ km
millimetre of mercurymm Hgblood pressure and pressure of other body fluids133.322 Pa
barnbeffective cross-sectional area1 × 10⁻²⁸ m² = 100 fm²

Source: European Directive 80/181/EEC, as amended on 2019-07-23.





Unicode symbols

Symbol Code point Name
Symbols for measurement units and prefixes
° 00B0 Degree sign
Ω 03A9 Greek capital letter omega
′ 2032 Prime
″ 2033 Double prime
μ 03BC Greek small letter mu
Decimal separators and spaces
, 002C Comma
. 002E Full stop
2020 Space
20A0 No-break space
  202F Narrow no-break space
Mathematical symbols
+ 002B Plus sign
− 2212 Minus sign
⋅ 22C5 Dot operator
× 00D7 Multiplication sign
÷ 00F7 Division sign
∕ 2215 Division slash
/ 002F Solidus
± 00B1 Plus-minus sign
= 003D Equals sign
≈ 2248 Almost equal to
% 0025 Percent sign
‰ 2030 Per mille sign
π 03C0 Greek small letter pi
Superscript numbers and mathematical symbols
⁺ 207A Superscript plus sign
⁻ 207B Superscript minus
⁰ 2070 Superscript zero
¹ 00B9 Superscript one
² 00B2 Superscript two
³ 00B3 Superscript three
⁴ 2074 Superscript four
⁵ 2075 Superscript five
⁶ 2076 Superscript six
⁷ 2077 Superscript seven
⁸ 2078 Superscript eight
⁹ 2079 Superscript nine




Obsolete units which used to be permitted fully or partly in the European Union 🇪🇺

NameSym­bolUnit ofEquivalent
curieCiactivity (of a radionuclide)37 000 000 000 Bq = 37 GBq
radradabsorbed dose0.01 Gy = 10 mGy
remremequivalent dose0.01 Sv = 10 mSv
röntgenRexposure (X and γ rays)0.000 258 C ∕ kg = 258 μC ∕ kg
poisePdynamic viscosity0.1 Pa ⋅ s = 0.1 N ⋅ s ∕ m²
stokesStkinematic viscosity0.000 1 m² ∕ s
dynedynforce0.000 01 N = 10 μN
ergergenergy0.000 000 1 J = 100 nJ
galGalacceleration due to gravity0.01 m ∕ s²
ångströmÅwavelength, atomic distances0.000 000 000 1 m = 100 pm
quintalqmass100 kg
standard atmosphereatmpressure101 325 Pa = 101.325 kPa
FestmeterFmvolume (forestry and timber trade)1 m³
Raummeter, stèreRm, stvolume (forestry and timber trade)1 m³
kilogramme-force, kilopondkgf, kpforce9.806 65 N
torr–pressure(101 325 ∕ 760) Pa ≈ 133.322 368 Pa
technical atmosphereatpressure98 066.5 Pa = 98.066 5 kPa
metre of watermH₂0pressure9 806.65 Pa = 9.806 65 kPa
Pferdestärke, Paardekracht, cheval vapeur, cavallo vaporePS, pk, CV, cvpower735.498 75 W
caloriecalquantity of heat4.186 8 J
thermiethquantity of heat4 186 800 J = 4.186 8 MJ
frigoriefgquantity of heat4 186.8 J = 4.186 8 kJ
stilbsbluminance10 000 cd ∕ m²
inchinlength≈ 0.025 4 m ≈ 2.54 cm
footftlength≈ 0.304 8 m ≈ 30.48 cm
mile–length≈ 1 609 m ≈ 1.609 km
yardydlength≈ 0.914 4 m ≈ 91.44 cm
square footsq ftarea≈ 0.092 9 m² ≈ 929 cm²
acreacarea≈ 4 047 m² ≈ 0.404 7 ha
square yardsq ydarea≈ 0.836 1 m² ≈ 8 361 cm²
fluid ouncefl ozvolume≈ 0.000 028 41 m³ ≈ 0.028 41 l ≈ 28.41 ml
gill–volume≈ 0.000 142 1 m³ ≈ 0.142 1 l ≈ 142.1 ml
pintptvolume≈ 0.000 568 3 m³ ≈ 0.568 3 l ≈ 568.3 ml
quartqtvolume≈ 0.001 137 m³ ≈ 1.137 l
gallongalvolume≈ 0.004 546 m³ ≈ 4.546 l
ounce (avoirdupois)ozmass≈ 0.028 35 kg ≈ 28.35 g
troy ounceoz trmass≈ 0.031 1 kg ≈ 31.1 g
poundlbmass≈ 0.453 6 kg ≈ 453.6 g
therm–energy≈ 105 506 000 J ≈ 105.506 MJ ≈ 29.307 2 kWh
fathomfmlength≈ 1.829 m

The grade or gon also used to have the unit symbol ᵍ. The kelvin also used to be called degree kelvin and had the unit symbol °K.

Source: European Directives 71/354/EEC (1971) and 80/181/EEC.