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Unit of measure converter


Units measurement conversion: Length Area Volume Mass Force Power Energy Time Temperature Angle Speed Flow Acceleration Pressure Electrical Luminance ...

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Content

  How to use the conversion tool

  How to make an equivalence

Prefixes

Base Units

Physical Measure

Other Measure

Length

Area

Volume

Plane angle

Mass

Density

Time

Frequency

Speed or velocity

Flow (volume)

Acceleration

Force

Pressure or mechanical stress

Torque or moment of force

Energy, work, or amount of heat

Power or heat flow rate

Dynamic viscosity

Kinematic viscosity

Electric current

Electric charge

Voltage, electromotive force

Magnetic flux

Magnetic flux density

Temperature

Information entropy

Luminous intensity

Luminance

Illuminance

Radioactivity

  Comment

  References

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How to use the conversion tool

Select the size measurement from the top combo (length, weight, ...)
Combo numeric field
 # select the From
 # select your To unit
 # enter a numeric value in the From field (default = 1).
 # displays the value of conversion in the field result.
Table
 # The table below lists all the results together.
 # select with the mouse lines of a table, the cell will be updated with the value to be converted, while in the other cell lines the results show the value of the conversion from the size selected.
 # The result cell of the unit selected is editable (hold the left mouse button).

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How to make an equivalence

All units of a physical measure are linked via a conversion factor. On this web page for every unit you can find the conversion factor compared to the base unit (SI unit).
To do a conversion (or equivalent) you must multiply the value to be converted by the conversion factor of the start unit and then divide the result by the conversion factor of the destination unit.

For example, we want to know how many centimeters equals 12 yards?
 # convert the units in meters (which is the SI base unit for the lengths)
 # 1 yard = 0.9144 meters
 # 1 centimeters = 0.01 meters
 # derive the conversion factor between the yard and centimeters by dividing the factors found
 # 0.9144 / 0.01 = 91.44
 # 1 yd = 91.44 cm
 # now we multiply the amount to be converted by the conversion factor found
 # 12 * 91.44 = 1097.28
 # result: 12 yd equals 1097.28 cm

Unit conversion tool implements this simple algorithm.

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Prefixes

A prefix may be added to a unit to produce a multiple of the original unit. All multiples are integer powers of ten. For example, kilo- denotes a multiple of a thousand and milli- denotes a multiple of a thousandth; hence there are one thousand millimetres to the metre and one thousand metres to the kilometre. The prefixes are never combined: a millionth of a kilogram is a milligram not a microkilogram.

PrefixSymbol10nDecimal equivalent
yottaY10e+241 000 000 000 000 000 000 000 000
zettaZ10e+211 000 000 000 000 000 000 000
exaE10e+181 000 000 000 000 000 000
petaP10e+151 000 000 000 000 000
teraT10e+121 000 000 000 000
gigaG10e+91 000 000 000
megaM10e+61 000 000
kilok10e+31 000
hectoh10e+2100
decada10e+110
decid10e-10.1
centic10e-20.01
millim10e-30.001
microµ10e-60.000 001
nanon10e-90.000 000 001
picop10e-120.000 000 000 001
femtof10e-150.000 000 000 000 001
attoa10e-180.000 000 000 000 000 001
zeptoz10e-210.000 000 000 000 000 000 001
yoctoy10e-240.000 000 000 000 000 000 000 001

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Base Units

The International System of Units (SI) defines seven SI base units. For a set of physical quantities of measure, or dimensions, that are used to define all other SI units, known as SI derived units.

UnitSymbolMeasure
MetremLength
KilogramkgMass
SecondsTime
AmpereAElectric current
KelvinKThermodynamic temperature
CandlecdLuminous intensity
MolemolAmount of substance

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Physical Measure

Physical measure

Physical measureSymbol of the measureName of the unit SISymbol of the unit SIEquivalence with the unit SI
FrequencefhertzHzs-1
ForceFnewtonNkg × m × s-2
Pressure, stress, vapor pressureppascalPaN × m-2
Energy, work, heatE, QjouleJN × m
Power, radiant fluxP, WwattWJ × s-1
Electric chargeqcoulombCA × s
Electric potential, electromotive force, voltageV, EvoltVJ × C-1
Electrical resistanceRohmOV × A-1
Electrical conductanceGsiemensSA × V-1
Electrical capacityCfaradFC × V-1
Magnetic flux densityBteslaTV × s × m-2
Magnetic fluxF(B)weberWbV × s
InductanceLhenryHV × s × A-1
TemperatureTdegree Celsius°CK[3]
Plane anglefradiantrad1
Solid angleOsteradiansr1
Luminous flux.lumenlmcd × sr
Illuminance luxlxcd × sr × m-2
RefractionDdiopterDm-1
Activity of a radionuclideAbecquerelBqs-1
Absorbed doseDgrayGyJ × kg-1
Dose equivalentHsievertSvJ × kg-1
Effective doseEsievertSvJ × kg-1
Catalytic activitykatalkatmol × s-1

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Other Measure

Physical measure

Physical measureSymbol of the measureName of the unit SISymbol of the unit SIEquivalence with the unit SI
areaAsquare meterm2
volumeVcubic meterm3
velocity, speedvmetre per secondm/sm × s-1
angular velocitys-1 ; rad × s-1
accelerationam × s-2
torqueN × m
wavenumbernm-1
densitykilogram per cubic meterkg/m³kg × m-3
specific volumem3 × kg-1
molars SImol × dm-3
molar volumeVmm3 × mol-1
heat capacity, entropyC, SJ × K-1
molar heat, molar entropyCm, SmJ × K-1 × mol-1
specific heat, specific entropyc, sJ × K-1 × kg-1
molar energyEmJ × mol-1
specific energyeJ × kg-1
energy densityUJ × m-3
surface tensionsN × m-1
energy flux density, irradiancesW × m-2
thermal conductivityW × m-1 × K-1
kinematic viscosity, diffusion coefficientm2 × s-1
dynamic viscosityN × s × m-2
density of electric chargeC × m-3
electric current densityjA × m-2
electrical conductivityS × m-1
molar conductivityS × m2 × mol-1
dielectric constanteF × m-1
magnetic permeabilityµH × m-1
(intensity) of the electric fieldF, EV × m-1
(intensity) of the magnetic fieldHA × m-1
magnetizationMA × m-1
luminancecd × m-2
exposure (X and gamma rays)C × kg-1
absorbed dose rateGy × s-1

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Length      convert  Convert

Length is the long dimension of any object. The length of a thing is the distance between its ends, its linear extent as measured from end to end. This may be distinguished from height, which is vertical extent, and width or breadth, which are the distance from side to side, measuring across the object at right angles to the length. In the physical sciences and engineering, the word "length" is typically used synonymously with "distance", with symbol l or L or letter-like symbol l. In the International System of Units (SI), the basic unit of length is the meter and is now defined in terms of the speed of light.

UnitSymbolDefinitionFactor
ångströmÅ= 1 × 10-10 m0.1e-9
astronomical unitAUDistance from Earth to Sun149597871464
barleycorn (H)= in (see note above about rounding)8.46e-3
bohr, atomic unit of lengtha0= Bohr radius of hydrogen5.2917720859e-11
cable length (Imperial)= 608 ft185.3184
cable length (International)= 1/10 nmi185.2
cable length (U.S.)= 720 ft219.456
centimeterscm= 0.01 mt0.01
chain (Gunter´s; Surveyor´s)ch= 66 ft = 4 rods20.1168
cubit (H)= Distance from fingers to elbow 18in0.5
ell (H)ell= 45 in1.143
fathomfm= 6 ft1.8288
fermifm= 1 × 10-15 m1e-15
finger= 7/8 in0.022225
finger (cloth)= 4½ in0.1143
foot (Benoît) (H)ft(Ben)0.304799735
foot (Clarke´s; Cape) (H)ft(Cla)0.3047972654
foot (Indian) (H)ftInd0.304799514
foot (International)ft= yd = 12 inches0.3048
foot (Sear´s) (H)ft(Sear)0.30479947
foot (U.S. Survey)ft(US)= 1 200/3 937 m0.304800610
french; charriereF= mm3.3e-4
furlongfur= 10 chains = 660 ft = 220 yd201.168
hand= 4 in0.1016
inchin= 1/36 yd = 1/12 ft0.0254
kilometerskm= 1000 mt1000
league (land)lea= 3 US Statute miles4828.032
light-day= 24 light-hours2.59020683712e13
light-hour= 60 light-minutes1.0792528488e12
light-minute= 60 light-seconds1.798754748e10
light-second= Distance light travels in one second in vacuum2.99792458e8
light-yearl.y.= Distance light travels in vacuum in 365.25 days9.4607304725808e15
lineln= 1/12 in0.002116
link (Gunter´s; Surveyor´s)lnk= 1/100 ch0.201168
link (Ramsden´s; Engineer´s)lnk= 1 ft0.3048
metre (SI base unit)m= Distance light travels in 1/299 792 458 of a second in vacuum.1
mickey= 1/200 in1.27e-4
micronµ1e-6
mil; thoumil= 1 × 10-3 in2.54e-5
mil (Sweden and Norway)mil= 10 km10000
milemi= 1 760 yd = 5 280 ft = 80 chains1609.344
mile (geographical) (H)= 6 082 ft1853.7936
mile (telegraph) (H)mi= 6 087 ft1855.3176
mile (U.S. Survey)mi= 5 280 ft (US Survey feet)1609.347219
millimetersmm= 0.001 mt0.001
nail (cloth)= 2¼ in0.05715
nautical leagueNL;nl= 3 nmi5556
nautical mile (Admiralty)NM(Adm);nmi(Adm)= 6 080 ft1853.184
nautical mile (international)NM;nmi= 1 852 m1852
pace= 2.5 ft0.762
palm= 3 in0.0762
parsecpcDistance of star with parallax shift of one arc second from a base of one astronomical unit3.08567782e16
pica= 12 pointsDependent on pointeasures.
point (American, English)pt= 1/72.272 in0.000351450
point (Didot; European)pt= 1/12 × 1/72 of pied du roi;0.00037593985
point (PostScript)pt= 1/72 in0.0003527
point (TeX)pt= 1/72.27 in0.0003514598
quarter= ¼ yd0.2286
rod; pole; perch (H)rd= 16½ ft5.0292
rope (H)rope= 20 ft6.096
span (H)= 9 in0.2286
spat1e12
stick (H)= 2 in0.0508
stigma; bicron (picometre)pm1e-12
twiptwp= 1/1 440 in1.7638e-5
x unit; siegbahnxu1.0021e-13
yard (International)yd= 0.9144 m = 3 ft = 36 in0.9144

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Area      convert  Convert

Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved then the definition of arc length of a curve.

UnitSymbolDefinitionFactor
acre (international)ac= 10 sq ch = 4 840 sq yd4046.8564224
acre (U. S. survey)ac= 10 sq ch = 4 840 sq yd4046.873
area= 100 m2100
barnb= 10-28 m21e-28
barony= 4 000 ac1.61874256896e7
boardbd= 1 in × 1 ft7.74192e-3
boiler horsepower equivalent direct radiationbhp EDR= (1 ft2) (1 bhp) / (240 BTUIT/h)12.958174
circular inchcirc in= p/4 sq in5.067075e-4
circular mil; circular thoucirc mil= p/4 mil25.067075e-10
cord= 192 bd1.48644864
dunam= 1 000 m21000
hectareha= 10 000 m210000
hide= 100 ac4.0468564224e5
roodro= ¼ ac1011.7141056
shed= 10-52 m21e-52
square chainsq ch= 1/10 ac404.68564224
square footsq ft= 1 ft × 1 ft9.290304e-2
square foot (U.S. Survey)sq ft= 1 ft (US) × 1 ft (US)9.29034116132749e-2
square inchsq in= 1 in × 1 in6.4516e-4
square kilometrekm2= 1 km × 1 km1e6
square linksq lnk= 1 lnk × 1 lnk4.0468564224e-2
square metre (SI unit)m2= 1 m × 1 m1
square mil; square thousq mil= 1 mil × 1 mil6.516e-10
square mile; sectionsq mi= 1 mi × 1 mi2.589988110336e6
square mile (U.S. Survey)sq mi= 1 mi (US) × 1 mi (US)2.589998e6
square rod/pole/perchsq rd= 1 rd × 1 rd25.29285264
square yardsq yd= 1 yd × 1 yd0.83612736
stremma= 1 000 m21000
township= 36 sq mi (US)9.323994e7
yardland= 30 ac1.21405692672e5

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Volume      convert  Convert

The volume of any solid, liquid, gas, plasma, theoretical object, or vacuum is how much three-dimensional space it occupies, often quantified numerically. One-dimensional figures (such as lines) and two-dimensional shapes (such as squares) are assigned zero volume in the three-dimensional space. Volume is commonly presented in units such as cubic meters, cubic centimeters, litres, or millilitres.

UnitSymbolDefinitionFactor
acre-footac ft= 1 ac x 1 ft = 43 560 ft31233.48183754752
acre-inch= 1 ac × 1 in102.79015312896
barrel (Imperial)bl (Imp)= 36 gal (Imp)0.16365924
barrel (petroleum)bl; bbl= 42 gal (US)0.158987294928
barrel (U.S. dry)bl (US)= 105 qt (US) = 105/32 bu (US lvl)0.115628198985075
barrel (U.S. fluid)fl bl (US)= 31½ gal (US)0.119240471196
board-footfbm= 144 cu in2.359737216e-3
bucket (Imperial)bkt= 4 gal (Imp)0.01818436
bushel (Imperial)bu (Imp)= 8 gal (Imp)0.03636872
bushel (U.S. dry heaped)bu (US)= 1 ¼ bu (US lvl)0.0440488377086
bushel (U.S. dry level)bu (US lvl)= 2 150.42 cu in0.03523907016688
butt, pipe= 126 gal (wine)0.476961884784
coomb= 4 bu (Imp)0.14547488
cord (firewood)= 8 ft × 4 ft × 4 ft3.624556363776
cord-foot= 16 cu ft0.453069545472
cubic fathomcu fm= 1 fm × 1 fm × 1 fm6.116438863872
cubic footcu ft= 1 ft × 1 ft × 1 ft0.028316846592
cubic inchcu in= 1 in × 1 in × 1 in16.387064e-6
cubic metre (SI unit)m3= 1 m × 1 m × 1 m1
cubic milecu mi= 1 mi × 1 mi × 1 mi4168181825.440579584
cubic yardcu yd= 27 cu ft0.764554857984
cup (breakfast)= 10 fl oz (Imp)284.130625e-6
cup (Canadian)c (CA)= 8 fl oz (Imp)227.3045e-6
cup (metric)c= 250.0 × 10-6 m3250.0e-6
cup (U.S. customary)c (US)= 8 US fl oz = 1/16 gal (US)236.5882365e-6
cup (U.S. food nutrition labeling)c (US)= 240 mL2.4e-4
dash (Imperial)= 1/384 gi (Imp) = ½ pinch (Imp)369.961751302083e-9
dash (U.S.)= 1/96 US fl oz = ½ US pinch308.057599609375e-9
dessertspoon (Imperial)= 1/12 gi (Imp)11.8387760416e-6
drop (Imperial)gtt= 1/288 fl oz (Imp)98.6564670138e-9
drop (Imperial) (alt)gtt= 1/1 824 gi (Imp)77.886684e-9
drop (medical)= 1/12 ml83.03e-9
drop (metric)= 1/20 mL50.0e-9
drop (U.S.)gtt= 1/360 US fl oz82.14869322916e-9
drop (U.S.) (alt)gtt= 1/456 US fl oz64.854231e-9
fifth= 1/5 US gal757.0823568e-6
firkin= 9 gal (US)0.034068706056
fluid drachm (Imperial)fl dr= fl oz (Imp)3.5516328125e-6
fluid dram (U.S.); U.S. fluidramfl dr= US fl oz3.6966911953125e-6
fluid ounce (Imperial)fl oz (Imp)= 1/160 gal (Imp)28.4130625e-6
fluid ounce (U.S. customary)US fl oz= 1/128 gal (US)29.5735295625e-6
fluid ounce (U.S. food nutrition labeling)US fl oz= 30 mL3e-5
fluid scruple (Imperial)fl s= 1/24 fl oz (Imp)1.18387760416e-6
gallon (beer)beer gal= 282 cu in4.621152048e-3
gallon (Imperial)gal (Imp)= 4.546 09 L4.54609e-3
gallon (U.S. dry)gal (US)= bu (US lvl)4.40488377086e-3
gallon (U.S. fluid; Wine)gal (US)= 231 cu in3.785411784e-3
gill (Imperial); Noggingi (Imp); nog= 5 fl oz (Imp)142.0653125e-6
gill (U.S.)gi (US)= 4 US fl oz118.29411825e-6
hogshead (Imperial)hhd (Imp)= 2 bl (Imp)0.32731848
hogshead (U.S.)hhd (US)= 2 fl bl (US)0.238480942392
jigger (bartending)= 1½ US fl oz44.36e-6
kilderkin= 18 gal (Imp)0.08182962
lambda= 1 mm31e-9
last= 80 bu (Imp)2.9094976
litreL= 1 dm30.001
load= 50 cu ft1.4158423296
minim (Imperial)min= 1/480 fl oz (Imp) = 1/60 fl dr (Imp)59.1938802083e-9
minim (U.S.)min= 1/480 US fl oz = 1/60 US fl dr61.611519921875e-9
peck (Imperial)pk= 2 gal (Imp)9.09218e-3
peck (U.S. dry)pk= ¼ US lvl bu8.80976754172e-3
perchper= 16½ ft × 1½ ft × 1 ft0.700841953152
pinch (Imperial)= 1/192 gi (Imp) = tsp (Imp)739.92350260416e-9
pinch (U.S.)= 1/48 US fl oz = US tsp616.11519921875e-9
pint (Imperial)pt (Imp)= gal (Imp)568.26125e-6
pint (U.S. dry)pt (US dry)= 1/64 bu (US lvl) = gal (US dry)550.6104713575e-6
pint (U.S. fluid)pt (US fl)= gal (US)473.176473e-6
pony= 3/4 US fl oz22.180147171875e-6
pottle; quartern= ½ gal (Imp) = 80 fl oz (Imp)2.273045e-3
quart (Imperial)qt (Imp)= ¼ gal (Imp)1.1365225e-3
quart (U.S. dry)qt (US)= 1/32 bu (US lvl) = ¼ gal (US dry)1.101220942715e-3
quart (U.S. fluid)qt (US)= ¼ gal (US fl)946.352946e-6
quarter; pail= 8 bu (Imp)0.29094976
register ton= 100 cu ft2.8316846592
sack (Imperial); bag= 3 bu (Imp)0.10910616
sack (U.S.)= 3 bu (US lvl)0.10571721050064
seam= 8 bu (US lvl)0.28191256133504
shot= 1 US fl oz29.57e-6
strike (Imperial)= 2 bu (Imp)0.07273744
strike (U.S.)= 2 bu (US lvl)0.07047814033376
tablespoon (Canadian)tbsp= ½ fl oz (Imp)14.20653125e-6
tablespoon (Imperial)tbsp= 5/8 fl oz (Imp)17.7581640625e-6
tablespoon (metric)15.0e-6
tablespoon (U.S. customary)tbsp= ½ US fl oz14.7867647825e-6
tablespoon (U.S. food nutrition labeling)tbsp= 15 mL1.5e-5
teaspoon (Canadian)tsp= 1/6 fl oz (Imp)4.735510416e-6
teaspoon (Imperial)tsp= 1/24 gi (Imp)5.91938802083e-6
teaspoon (metric)= 5.0 × 10-6 m35.0e-6
teaspoon (U.S. customary)tsp= 1/6 US fl oz4.928921595e-6
teaspoon (U.S. food nutrition labeling)tsp= 5 mL5e-6
timber foot= 1 cu ft0.028316846592
ton (displacement)= 35 cu ft0.99108963072
ton (freight)= 40 cu ft1.13267386368
ton (water)= 28 bu (Imp)1.01832416
tun= 252 gal (wine)0.953923769568
wey (U.S.)= 40 bu (US lvl)1.4095628066752

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Plane angle      convert  Convert

In geometry and trigonometry, an angle (in full, plane angle) is the figure formed by two rays sharing a common endpoint, called the vertex of the angle. The magnitude of the angle is the \"amount of rotation\" that separates the two rays, and can be measured by considering the length of circular arc swept out when one ray is rotated about the vertex to coincide with the other. Where there is no possibility of confusion, the term \"angle\" is used interchangeably for both the geometric configuration itself and for its angular magnitude (which is simply a numerical quantity).

UnitSymbolDefinitionFactor
angular milµ= 2p/6 400 rad0.981748e-3
arcminute´= 1°/600.290888e-3
arcsecond\"= 1°/3 6004.848137e-6
centesimal minute of arc´= 1 grad/1000.157080e-3
centesimal second of arc\"= 1 grad/10 0001.570796e-6
degree (of arc)°= p/180 rad = 1/360 of a revolution17.453293e-3
grad; gradian; gongrad= 2p/400 rad = 0.9°15.707963e-3
octant= 45°0.785398
quadrant= 90°1.570796
radian (SI unit)radThe angle subtended at the center of a circle by an arc whose length is equal to the circle´s radius. One full revolution encompasses 2p radians.1
sextant= 60°1.047198
sign= 30°0.523599

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Mass      convert  Convert

In the physical sciences, the weight of an object is the magnitude, W, of the force that must be applied to an object in order to support it (i.e. hold it at rest) in a gravitational field. The weight of an object equals the magnitude of the gravitational force acting on the object, less the effect of its buoyancy in any fluid in which it might be immersed. Near the surface of the Earth, the acceleration due to gravity is approximately constant; this means that an object´s weight near the surface of the Earth is roughly proportional to its mass.

UnitSymbolDefinitionFactor
atomic mass unit, unifiedu; AMU1.66053873e-27
atomic unit of mass, electron rest massme9.10938215e-31
bag (coffee)= 60 kg60
bag (Portland cement)= 94 lb av42.63768278
barge= 22½ sh tn20411.65665
caratkt= 3 1/6 gr205.196548333e-6
carat (metric)ct= 200 mg200e-6
clove= 8 lb av3.62873896
crith89.9349e-6
daltonDa1.66090210e-27
dram (apothecary; troy)dr t= 60 gr3.8879346e-3
dram (avoirdupois)dr av= 27 11/32 gr1.7718451953125e-3
electronvolteV= 1 eV (energy unit) / c21.7826e-36
gamma= 1 µg1e-9
graingr= 64.798 91 mg64.79891e-6
hundredweight (long)long cwt or cwt= 112 lb av50.80234544
hundredweight (short); centalsh cwt= 100 lb av45.359237
hyl (CGS unit)= 1 gee × 1 g × 1 s2/m9.80665e-3
hyl (MKS unit)= 1 gee × 1 kg × 1 s2/m9.80665
kilogram, grave (SI unit)kg; G1
kipkip= 1 000 lb av453.59237
mark= 8 oz t248.8278144e-3
mite= 1/20 gr3.2399455e-6
mite (metric)= 1/20 g50e-6
ounce (apothecary; troy)oz t= 1/12 lb t31.1034768e-3
ounce (avoirdupois)oz av= 1/16 lb28.349523125e-3
ounce (U.S. food nutrition labeling)oz= 28 g28e-3
pennyweightdwt; pwt= 1/20 oz t1.55517384e-3
point= 1/100 ct2e-6
pound (avoirdupois)lb av= 7 000 grains0.45359237
pound (metric)= 500 g500e-3
pound (troy)lb t= 5 760 grains0.3732417216
quarter (Imperial)= 1/4 long cwt = 2 st = 28 lb av12.70058636
quarter (informal)= ¼ short tn226.796185
quarter, long (informal)= ¼ long tn254.0117272
quintal (metric)q= 100 kg100
scruple (apothecary)s ap= 20 gr1.2959782e-3
sheet= 1/700 lb av647.9891e-6
slug; geepoundslug= 1 gee × 1 lb av × 1 s2/ft14.593903
stonest= 14 lb av6.35029318
ton, assay (long)AT= 1 mg × 1 long tn ÷ 1 oz t32.666667e-3
ton, assay (short)AT= 1 mg × 1 sh tn ÷ 1 oz t29.166667e-3
ton, longlong tn or ton= 2 240 lb1016.0469088
ton, shortsh tn= 2 000 lb907.18474
tonne (mts unit)t= 1 000 kg1000
wey= 252 lb = 18 st114.30527724
ZentnerZtr.Definitions vary--

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Density      convert  Convert

The density of a material is defined as its mass per unit volume.

UnitSymbolDefinitionFactor
gram per millilitreg/mL= g/mL1
kilogram per cubic metre (SI unit)kg/m3= kg/m31
kilogram per litre kg/L= kg/L1
ounce (avoirdupois) per cubic footoz/ft3= oz/ft31.001153961
ounce (avoirdupois) per cubic inchoz/in3= oz/in31.729994044e3
ounce (avoirdupois) per gallon (Imperial)oz/gal= oz/gal6.236023291
ounce (avoirdupois) per gallon (U.S. fluid)oz/gal= oz/gal7.489151707
pound (avoirdupois) per cubic footlb/ft3= lb/ft316.01846337
pound (avoirdupois) per cubic inchlb/in3= lb/in32.767990471e4
pound (avoirdupois) per gallon (Imperial)lb/gal= lb/gal99.77637266
pound (avoirdupois) per gallon (U.S. fluid)lb/gal= lb/gal119.8264273
slug per cubic footslug/ft3= slug/ft3515.3788184

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Time      convert  Convert

In physics as well as in other sciences, time is considered one of the few fundamental quantities. Time is used to define other quantities - such as velocity - so defining time in terms of such quantities would result in circularity of definition. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event (such as the passage of a free-swinging pendulum) constitutes one standard unit such as the second, is highly useful in the conduct of both advanced experiments and everyday affairs of life.

UnitSymbolDefinitionFactor
atomic unit of timeau= a0/(a×c)2.418884254e-17
Callippic cycle= 441 mo (hollow) + 499 mo (full) = 76 a of 365.25 d2.3983776e9
century= 100 a (see below for definition of year length)3155695200
dayd= 24 h86400
day (sidereal)d= Time needed for the Earth to rotate once around its axis, determined from successive transits of a very distant astronomical object across an observer´s meridian (International Celestial Reference Frame)86164.1
decade= 10 a (see below for definition of year length)315569520
fortnight= 2 wk1209600
helek= 1/1 080 h3.3
Hipparchic cycle= 4 Callippic cycles - 1 d9.593424e9
hourh= 60 min3600
jiffy= 1/60 s0.01666666666666
jiffy (alternate)= 1/100 s10e-6
ke (quarter of an hour)= ¼ h = 1/96 d = 60 × 60 / 4 s = 900 s = 60 / 4 min = 15 min900
ke (traditional)= 1/100 d = 24 × 60 × 60 / 100 s = 864 s = 24 * 60 / 100 min = 14.4 min864
lustre; lustrum= 5 a of 365 d1.5768e8
Metonic cycle; enneadecaeteris= 110 mo (hollow) + 125 mo (full) = 6940 d 19 a5.99616e8
millennium= 1 000 a (see below for definition of year length)31556952000
millidaymd= 1/1 000 d = 24 × 60 × 60 / 1 000 s86.4
minutemin= 60 s60
moment= 90 s90
month (full)mo= 30 d2592000
month (hollow)mo= 29 d2505600
octaeteris= 48 mo (full) + 48 mo (hollow) + 3 mo (full) = 8 a of 365.25 d = 2922 d2.524608e8
Planck time= (G/c5)½1.351211868e-43
second (SI unit)stime 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)1
shake= 10-8 s10e-9
sigma= 10-6 s1e-6
Sothic cycle= 1 461 a of 365 d4.6074096e10
svedbergS= 10-13 s10e-13
weekwk= 7 d604800
year (Gregorian)a, y, or yr= 365.2425 d average, calculated from common years (365 d) plus leap years (366 d) on most years divisible by 4. See leap year for details.31556952
year (Julian)a, y, or yr= 365.25 d average, calculated from common years (365 d) plus one leap year (366 d) every four years31557600
year (sidereal)a, y, or yr= time taken for Sun to return to the same position with respect to the stars of the celestial sphere 365.256 363 d 31 558 149.7632 s31558149.7632
year (tropical)a, y, or yr= Length of time it takes for the Sun to return to the same position in the cycle of seasons 365.242 190 d 31 556 925 s31556925

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Frequency      convert  Convert

Number of cycles per period.

UnitSymbolDefinitionFactor
hertz (SI unit)Hz= Number of cycles per second1
revolutions per minuterpm= One unit rpm equals one rotation completed around a fixed axis in one minute of time (0.104719755 rad/s).0.6579736259874460368649291834988

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Speed or velocity      convert  Convert

Speed is a scalar quantity with dimensions length/time; the equivalent vector quantity to speed is velocity. Speed is measured in the same physical units of measurement as velocity, but does not contain the element of direction that velocity has. Speed is thus the magnitude component of velocity.

UnitSymbolDefinitionFactor
foot per hourfph= 1 ft/h8.466667e-5
foot per minutefpm= 1 ft/min5.08e-3
foot per secondfps= 1 ft/s3.048e-1
furlong per fortnight= furlong/fortnight1.663095e-4
inch per minuteipm= 1 in/min4.23333e-4
inch per secondips= 1 in/s2.54e-2
kilometre per hourkm/h= 1 km/h2.777778e-1
knotkn= 1 NM/h = 1.852 km/h0.514444
knot (Admiralty)kn= 1 NM (Adm)/h = 1.853 184 km/h[citation needed]0.514773
mach numberMThe ratio of the speed of an object moving through a fluid to the speed of sound in the same medium; typically used as a measure of aircraft speed.--
metre per second (SI unit)m/s= 1 m/s1
mile per hourmph= 1 mi/h0.44704
mile per minutempm= 1 mi/min26.8224
mile per secondmps= 1 mi/s1609.344
speed of light in vacuumc= 299 792 458 m/s299792458
speed of sound in airs344 m/s at 20 °C, 60% relative humidity344

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Flow (volume)      convert  Convert

Flow (volume).

UnitSymbolDefinitionFactor
cubic foot per minuteCFM= 1 ft3/min4.719474432e-4
cubic foot per secondft3/s= 1 ft3/s0.028316846592
cubic inch per minutein3/min= 1 in3/min2.7311773e-7
cubic inch per secondin3/s= 1 in3/s1.6387064e-5
cubic metre per second (SI unit)m3/s= 1 m3/s1
gallon (U.S. fluid) per dayGPD= 1 gal/d4.381263638e-8
gallon (U.S. fluid) per hourGPH= 1 gal/h1.051503273e-6
gallon (U.S. fluid) per minuteGPM= 1 gal/min6.30901964e-5
litre per minuteLPM= 1 L/min1.6e-5

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Acceleration      convert  Convert

In physics, and more specifically kinematics, acceleration is the change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, acceleration is the rate at which something speeds up or slows down. However, as a vector quantity, acceleration is also the rate at which direction changes. Acceleration has the dimensions L T-2. In SI units, acceleration is measured in metres per second squared (m/s2).

UnitSymbolDefinitionFactor
foot per hour per secondfph/s= 1 ft/(h×s)8.466667e-5
foot per minute per secondfpm/s= 1 ft/(min×s)5.08e-3
foot per second squaredfps2= 1 ft/s23.048e-1
gal; galileoGal= 1 cm/s210-2
inch per minute per secondipm/s= 1 in/(min×s)4.233333e-4
inch per second squaredips2= 1 in/s22.54e-2
knot per secondkn/s= 1 kn/s5.144444e-1
metre per second squared (SI unit)m/s2= 1 m/s21
mile per hour per secondmph/s= 1 mi/(h×s)4.4704e-1
mile per minute per secondmpm/s= 1 mi/(min×s)26.8224
mile per second squaredmps2= 1 mi/s21.609344e3
standard gravityg= 9.806 65 m/s29.80665

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Force      convert  Convert

In physics, a force is any agent that causes a change in the motion of a free body, or that causes stress in a fixed body. It can also be described by intuitive concepts such as a push or pull that can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate, or which can cause a flexible object to deform. Force has both magnitude and direction, making it a vector quantity. Newton´s second law states that an object with a constant mass will accelerate in proportion to the net force acting upon and in inverse proportion to its mass. Equivalently, the net force on an object equals the rate at which its momentum changes.

UnitSymbolDefinitionFactor
atomic unit of force= me×a2×c2/a08.23872206e-8
dyne (cgs unit)dyn= g×cm/s21e-5
kilogram-force; kilopond; grave-forcekgf;kp;Gf= g × 1 kg9.80665
kip; kip-forcekip;kipf;klbf= g × 1 000 lb4.4482216152605e3
milligrave-force, gravet-forcemGf;gf= g × 1 g9.80665e-3
newton (SI unit)NA force capable of giving a mass of one kg an acceleration of one meter per second, per second. = 1 N = 1 kg×m/s21
ounce-forceozf= g × 1 oz0.2780138509537812
poundlb= slug×ft/s24.448230531
pound-forcelbf= g × 1 lb4.4482216152605
poundalpdl= 1 lb×ft/s20.138254954376
sthene (mts unit)sn= 1 t×m/s21e3
ton-forcetnf= g × 1 sh tn8.896443230521e3

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Pressure or mechanical stress      convert  Convert

Pressure (symbol: p or P) is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.

UnitSymbolDefinitionFactor
atmosphere (standard)atm101325
atmosphere (technical)at= 1 kgf/cm29.80665e4
barbar105
barye (cgs unit)= 1 dyn/cm20.1
centimetre of mercurycmHg= 13 595.1 kg/m3 × 1 cm × g1.33322e3
centimetre of water (4 °C)cmH2O999.972 kg/m3 × 1 cm × g98.0638
foot of mercury (conventional)ftHg= 13 595.1 kg/m3 × 1 ft × g40.63666e3
foot of water (39.2 °F)ftH2O999.972 kg/m3 × 1 ft × g2.98898e3
inch of mercury (conventional)inHg= 13 595.1 kg/m3 × 1 in × g3.386389e3
inch of water (39.2 °F)inH2O999.972 kg/m3 × 1 in × g249.082
kilogram-force per square millimetrekgf/mm2= 1 kgf/mm29.80665e6
kip per square inchksi= 1 kipf/sq in6.894757e6
micron (micrometre) of mercuryµmHg= 13 595.1 kg/m3 × 1 µm × g 0.001 torr0.1333224
millimetre of mercurymmHg= 13 595.1 kg/m3 × 1 mm × g 1 torr133.3224
millimetre of water (3.98 °C)mmH2O999.972 kg/m3 × 1 mm × g = 0.999 972 kgf/m29.80638
pascal (SI unit)Pa= N/m2 = kg/(m×s2)1
pièze (mts unit)pz= 1 000 kg/m×s21e3
pound per square footpsf= 1 lbf/ft247.88025
pound per square inchpsi= 1 lbf/in26.894757e3
poundal per square footpdl/sqft= 1 pdl/sq ft1.488164
short ton per square foot= 1 sh tn × g / 1 sq ft95.760518e3
torrtorr= 101 325/760 Pa133.3224

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Torque or moment of force      convert  Convert

Torque, also called moment or moment of force, is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist. In more basic terms, torque measures how hard something is rotated. For example, imagine a wrench or spanner trying to twist a nut or bolt. The amount of \"twist\" (torque) depends on how long the wrench is, how hard you push down on it, and how well you are pushing it in the correct direction.

UnitSymbolDefinitionFactor
foot-pound forceftlbf= g × 1 lb × 1 ft1.3558179483314004
foot-poundalftpdl= 1 lb×ft2/s24.21401100938048e-2
inch-pound forceinlbf= g × 1 lb × 1 in0.1129848290276167
Newton metre (SI unit)N×m= N × m = kg×m2/s21

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Energy, work, or amount of heat      convert  Convert

In physics, is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law. Different forms of energy include kinetic, potential, thermal, gravitational, sound, light, elastic, and electromagnetic energy. The forms of energy are often named after a related force. Any form of energy can be transformed into another form, but the total energy always remains the same. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether´s theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.

UnitSymbolDefinitionFactor
barrel of oil equivalentbboe5.8 × 106 BTU59 °F6.12e9
British thermal unit (ISO)BTUISO= 1.0545 × 103 J1.0545e3
British thermal unit (International Table)BTUIT1.05505585262e3
British thermal unit (mean)BTUmean1.05587e3
British thermal unit (thermochemical)BTUth1.054350e3
British thermal unit (39 °F)BTU39°F1.05967e3
British thermal unit (59 °F)BTU59°F= 1.054 804 × 103 J1.054804e3
British thermal unit (60 °F)BTU60°F1.05468e3
British thermal unit (63 °F)BTU63°F1.0546e3
calorie (International Table)calIT= 4.1868 J4.1868
calorie (mean)calmean4.19002
calorie (thermochemical)calth= 4.184 J4.184
calorie (3.98 °C)cal3.98°C4.2045
calorie (15 °C)cal15°C= 4.1855 J4.1855
calorie (20 °C)cal20°C4.1819
Celsius heat unit (International Table)CHUIT= 1 BTUIT × 1 K/°R1.899100534716e3
cubic centimetre of atmosphereccatm;scc= 1 atm × 1 cm30.101325
cubic foot of atmosphere; standard cubic footcuftatm;scf= 1 atm × 1 ft32.8692044809344e3
cubic foot of natural gas= 1 000 BTUIT1.05505585262e6
cubic yard of atmosphere; standard cubic yardcuydatm;scy= 1 atm × 1 yd377.4685209852288e3
electronvolteV= e × 1 V1.60217733e-19
erg (cgs unit)erg= 1 g×cm2/s21e-7
foot-pound forceftlbf= g × 1 lb × 1 ft1.3558179483314004
foot-poundalftpdl= 1 lb×ft2/s24.21401100938048e-2
gallon-atmosphere (imperial)impgalatm= 1 atm × 1 gal (imp)460.63256925
gallon-atmosphere (US)USgalatm= 1 atm × 1 gal (US)383.5568490138
hartree, atomic unit of energyEh= me×a2×c2 (= 2 Ry)4.359744e-18
horsepower-hourhp×h= 1 hp × 1 h2.684519537696172792e6
inch-pound forceinlbf= g × 1 lb × 1 in0.1129848290276167
joule (SI unit)JThe work done when a force of one newton moves the point of its application a distance of one meter in the direction of the force. = 1 J = 1 m×N = 1 kg×m2/s21
kilocalorie; large caloriekcal;Cal= 1 000 calIT4.1868e3
kilowatt-hour; Board of Trade UnitkW×h;B.O.T.U.= 1 kW × 1 h3.6e6
litre-atmospherelatm;sl= 1 atm × 1 L101.325
quad= 1015 BTUIT1.05505585262e18
rydbergRy= R8×h×c2.179872e-18
therm (E.C.)= 100 000 BTUIT105.505585262e6
therm (U.S.)= 100 000 BTU59 °F105.4804e6
thermieth= 1 McalIT4.1868e6
ton of coal equivalentTCE= 7 Gcalth29.3076e9
ton of oil equivalentTOE= 10 Gcalth41.868e9
ton of TNTtTNT= 1 Gcalth4.184e9

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Power or heat flow rate      convert  Convert

In physics, power is the rate at which work is performed or energy is converted. It is an energy per unit of time. As a rate of change of work done or the energy of a subsystem, power is: P = W\t , where P is power, W is work and t is time.

UnitSymbolDefinitionFactor
atmosphere-cubic centimetre per minuteatmccm= 1 atm × 1 cm3/min1.68875e-3
atmosphere-cubic centimetre per secondatmccs= 1 atm × 1 cm3/s0.101325
atmosphere-cubic foot per houratmcfh= 1 atm × 1 cu ft/h0.797001244704
atmosphere-cubic foot per minuteatm×cfm= 1 atm × 1 cu ft/min47.82007468224
atmosphere-cubic foot per secondatmcfs= 1 atm × 1 cu ft/s2.8692044809344e3
BTU (International Table) per hourBTUIT/h= 1 BTUIT/h0.293071
BTU (International Table) per minuteBTUIT/min= 1 BTUIT/min17.584264
BTU (International Table) per secondBTUIT/s= 1 BTUIT/s1.05505585262e3
calorie (International Table) per secondcalIT/s= 1 calIT/s4.1868
foot-pound-force per hourftlbf/h= 1 ft lbf/h3.766161e-4
foot-pound-force per minuteftlbf/min= 1 ft lbf/min2.259696580552334e-2
foot-pound-force per secondftlbf/s= 1 ft lbf/s1.3558179483314004
horsepower (boiler)bhp34.5 lb/h × 970.3 BTUIT/lb9.810657e3
horsepower (European electrical)hp= 75 kp×m/s736
horsepower (Imperial electrical)hp= 746 W746
horsepower (Imperial mechanical)hp= 550 ft lbf/s745.69987158227022
horsepower (metric)hp= 75 m kgf/s735.49875
litre-atmosphere per minuteL×atm/min= 1 atm × 1 L/min1.68875
litre-atmosphere per secondL×atm/s= 1 atm × 1 L/s101.325
luseclusec= 1 L×µmHg/s1.333e-4
ponceletp= 100 m kgf/s980.665
square foot equivalent direct radiationsqftEDR= 240 BTUIT/h70.337057
ton of air conditioning= 1 t ice melted / 24 h3504
ton of refrigeration (Imperial)= 1 BTUIT × 1 lng tn/lb ÷ 10 min/s3.938875e3
ton of refrigeration (IT)= 1 BTUIT × 1 sh tn/lb ÷ 10 min/s3.516853e3
watt (SI unit)WThe 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/s31

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Dynamic viscosity      convert  Convert

Dynamic viscosity (or absolute viscosity) determines the dynamics of an incompressible Newtonian fluid. Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or extensional stress. Viscosity describes a fluid´s internal resistance to flow and may be thought of as a measure of fluid friction.

UnitSymbolDefinitionFactor
pascal second (SI unit)Pa×s= N×s/m2 , kg/(m×s)1
poise (cgs unit)P= 10-1 Pa×s0.1
pound per foot hourlb/(ft×h)= 1 lb/(ft×h)4.133789e-4
pound per foot secondlb/(ft×s)= 1 lb/(ft×s)1.488164
pound-force second per square footlbf×s/ft2= 1 lbf×s/ft247.88026
pound-force second per square inchlbf×s/in2= 1 lbf×s/in26894.757

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Kinematic viscosity      convert  Convert

Kinematic viscosity is the dynamic viscosity divided by the density for a Newtonian fluid.

UnitSymbolDefinitionFactor
square foot per secondft2/s= 1 ft2/s0.09290304
square metre per second (SI unit)m2/s= 1 m2/s1
stokes (cgs unit)St= 10-4 m2/s1e-4

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Electric current      convert  Convert

Electric current can mean, depending on the context, a flow of electric charge (a phenomenon) or the rate of flow of electric charge (a quantity). The electric charge that flows is carried by, for example, mobile electrons in a conductor, ions in an electrolyte or both in a plasma. The SI unit for rate of flow of electric charge is the ampere. Electric current is measured using an ammeter.

UnitSymbolDefinitionFactor
ampere (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
electromagnetic unit; abampere (cgs unit)abamp= 10 A10
esu per second; statampere (cgs unit)esu/s= (0.1 A×m/s) / c3.335641e-10

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Electric charge      convert  Convert

Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force, which is one of the four fundamental forces. The electric charge on a body may be positive or negative. Two positively charged bodies experience a mutual repulsive force, as do two negatively charged bodies. A positively charged body and a negatively charged body experience an attractive force.

UnitSymbolDefinitionFactor
abcoulomb; electromagnetic unit (cgs unit)abC;emu= 10 C10
atomic unit of chargeau= e1.602176462e-19
coulomb (SI unit)C= The amount of electricity carried in one second of time by one ampere of current. = 1 C = 1 A×s1
faradayF= 1 mol × NA×e96485.3383
statcoulomb; franklin; electrostatic unit (cgs unit)statC;Fr;esu= (0.1 A×m) / c3.335641e-10

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Voltage, electromotive force      convert  Convert

Voltage is commonly used as a short name for electrical potential difference. Its corresponding SI unit is the volt (symbol: V, not italicized). Electric potential is a hypothetically measurable physical dimension, and is denoted by the algebraic variable V (italicized). The voltage between two (electron) positions \"A\" and \"B\", inside a solid electrical conductor (or inside two electrically-connected, solid electrical conductors), is denoted by (VA - VB). This voltage is the electrical driving force that drives a conventional electric current in the direction A to B. Voltage can be directly measured by an voltmeter.

UnitSymbolDefinitionFactor
abvolt (cgs unit)abV= 1 × 10-8 V1e-8
statvolt (cgs unit)statV= c× (1 µJ/A×m)299.792458
volt (SI unit)VThe 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)1

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Magnetic flux      convert  Convert

Magnetic flux, represented by the Greek letter F (phi), is a measure of quantity of magnetism, taking into account the strength and the extent of a magnetic field. The SI unit of magnetic flux is the weber (in derived units: volt-seconds).

UnitSymbolDefinitionFactor
maxwell (CGS unit)Mx= 10-8 Wb1e-8
weber (SI unit)WbMagnetic 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)1

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Magnetic flux density      convert  Convert

Magnetic flux density, is the weber per square meter, or tesla.

UnitSymbolDefinitionFactor
gauss (CGS unit)G= Mx/cm2 = 10-4 T1e-4
tesla (SI unit)T= Wb/m2 = 1 T = 1 Wb/m2 = 1 kg/(A×s2)1

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Temperature      convert  Convert

In physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics. If no net heat flow occurs between two objects, the objects have the same temperature; otherwise heat flows from the hotter object to the colder object. This is the content of the zeroth law of thermodynamics. On the microscopic scale, temperature can be defined as the average energy in each degree of freedom in the particles in a system. Because temperature is a statistical property, a system must contain a few particles for the question as to its temperature to make any sense. For a solid, this energy is found in the vibrations of its atoms about their equilibrium positions. In an ideal monatomic gas, energy is found in the translational motions of the particles; with molecular gases, vibrational and rotational motions also provide thermodynamic degrees of freedom.

UnitSymbolDefinitionFactor
degree Celsius°C°C = K + 273.15. A unit of °C is the same size as a unit of K; however, their numerical values differ as the zero point of Celsius is set at 273.15 K (the ice point). [K] = [°C] - 273.15[°C]=[K]+273.15
degree Delisle°De[K] = 373.15 - [°De] × 2/3[°De]=(373.15-[K])*3/2
degree Fahrenheit°F0 °F = freezing pt. of H2O+NaCl, 180°F between freezing and boiling pt of H2O @ 1atm. [K] = ([°F] + 459.67) × 5/9[°F] = [K] × 1.8 - 459.67
degree Newton°N[K] = [°N] × 100/33 + 273.15[°N]=[K]*33/100-273.15
degree Rankine°R;°Ra0 °R = absolute zero. [K] = [°R] × 5/9[Ra]=[K] * 9 / 5
degree Réaumur°Ré[K] = [°Ré] × 5/4 + 273.15[°Ré]=[K]*4/5-273.15*4/5
degree Rømer°Rø[K] = ([°Rø] - 7.5) × 40/21 + 273.15[°Rø]=([K] - 273.15) * 21/40 + 7.5
kelvin (SI base unit)K= 1/273.16 of the thermodynamic temperature of the triple point of water.[K]=[K]

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Information entropy      convert  Convert

In information theory, entropy is a measure of the uncertainty associated with a random variable. The term by itself in this context usually refers to the Shannon entropy, which quantifies, in the sense of an expected value, the information contained in a message, usually in units such as bits.

UnitSymbolDefinitionFactor
SI unitJ/K= J/K1
nat; nip; nepitnat= kB1.3806505e-23
bit; shannonbit;b;Sh= ln(2) × kB9.569940e-24
ban; hartleyban;Hart= ln(10) × kB3.1790653e-23
nibble= 4 bits3.8279760e-23
byteB= 8 bits7.655952e-23
kilobyte (decimal)kB= 1 000 B7.655952e-20
kilobyte (kibibyte)KB;KiB= 1 024 B7.839695e-20

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Luminous intensity      convert  Convert

In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit.

UnitSymbolDefinitionFactor
candela (SI base unit); candlecdThe 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
candlepower (new)cp= cd The use of candlepower as a unit is discouraged due to its ambiguity.1
candlepower (old, pre-1948)cpVaries and is poorly eproducible. Approximately 0.981 cd.0.981

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Luminance      convert  Convert

Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square metre (cd/m2). A non-SI term for the same unit is the nit. The CGS unit of luminance is the stilb, which is equal to one candela per square centimetre or 10 kcd/m2.

UnitSymbolDefinitionFactor
candela per square footcd/ft2= cd/ft210.763910417
candela per square inchcd/in2= cd/in21550.0031
candela per square metre (SI unit)cd/m2= cd/m2 ; nit (deprecated)1
footlambertfL= (1/p) cd/ft23.4262590996
lambertL= (104/p) cd/m23183.0988618
stilb (CGS unit)sb= 104 cd/m21e4

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Illuminance      convert  Convert

In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of the intensity of the incident light, wavelength-weighted by the luminosity function to correlate with human brightness perception. Similarly, luminous emittance is the luminous flux per unit area emitted from a surface. Luminous emittance is also known as luminous exitance. In SI derived units, these are both measured in lux (lx) or lumens per square metre (cd×sr×m-2). In the CGS system, the unit of illuminance is the phot. One phot is equal to 10,000 lux. The foot-candle is a non-metric unit of illuminance that is used in photography.

UnitSymbolDefinitionFactor
footcandle; lumen per square footfc= lm/ft210.763910417
lumen per square inchlm/in2= lm/in21550.0031
lux (SI unit)lx= lm/m2 = 1 lx1
phot (CGS unit)ph= lm/cm21e4

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Radioactivity      convert  Convert

Radioactive decay is the process in which an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. The SI unit of activity is the becquerel (Bq). One Bq is defined as one transformation (or decay) per second. Since any reasonably-sized sample of radioactive material contains many atoms, a Bq is a tiny measure of activity; amounts on the order of TBq (terabecquerel) or GBq (gigabecquerel) are commonly used. Another unit of radioactivity is the curie, Ci, which was originally defined as the amount of radium emanation (radon-222) in equilibrium with of one gram of pure radium, isotope Ra-226. At present it is equal, by definition, to the activity of any radionuclide decaying with a disintegration rate of 3.7 * 1010 Bq. The use of Ci is presently discouraged by the SI.

UnitSymbolDefinitionFactor
becquerel (SI unit)Bq= Number of disintegrations per second = 1 Bq = 1/s1
curieCi= 3.7 × 1010 Bq3.7e10
rutherford (H)rd= 1 MBq1e6

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References

http://en.wikipedia.org/wiki/Conversion_of_units

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