Conversion of units

From Wikipedia, the free encyclopedia

Conversion of units refers to conversion factors between different units of measurement for the same quantity.

Contents 1 Techniques 1.1 Rounding of results 2 Tables of conversion factors 2.1 Length 2.2 Area 2.3 Volume 2.4 Angle 2.5 Solid angle 2.6 Mass 2.7 Density 2.8 Time 2.9 Speed or velocity 2.10 Acceleration 2.11 Force 2.12 Pressure or mechanical stress 2.13 Torque 2.14 Energy 2.15 Power 2.16 Angular momentum 2.17 Dynamic viscosity 2.18 Kinematic viscosity 2.19 Electric current 2.20 Electric charge 2.21 Electric Dipole 2.22 Electromotive force 2.23 Electrical resistance 2.24 Capacitance 2.25 Inductance 2.26 Magnetic field 2.27 Magnetic flux 2.28 Temperature 2.29 Information entropy 2.30 Radioactivity 2.31 Luminance 2.32 Radioactivity - absorbed dose 2.33 Radioactivity - equivalent dose 3 Software tools 3.1 Free conversion software 3.2 General commercial sources of converters 4 References 5 See also 6 External links

[edit] Techniques

[edit] Rounding of results

The process of making a conversion cannot produce a more precise result than the original quoted figure. Appropriate rounding of results is normally performed after conversion. (See significant figures).

[edit] Tables of conversion factors

This article gives lists of conversion factors for each of a number of physical quantities, which are listed in the index. For each physical quantity, a number of different units (some only of historical interest) are shown and expressed in terms of the corresponding SI unit.

Legend

Symbol	Definition
≡	exactly equal to
≈	approximately equal to
digits	indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369…)
(H)	of chiefly historical interest

[edit] Length

Length

Name of unit	Symbol	Definition	Relation to SI units
metre (SI base unit)	m	≡ Distance light travels in 1/299 792 458 of a second in vacuum	= 1 m
ångström	Å	≡ 1 × 10−10 m	= 0.1 nm
astronomical unit	AU	≈ Distance from Earth to Sun	≈ 149 597 871 464 m [1]
bohr, atomic unit of length	a0	≡ Bohr radius of hydrogen	≈ 5.291 772 0859 × 10−11 ± 3.6 × 10−20 m [2]
barleycorn (H)		≡ ⅓ in (see note above about rounding)	≈ 0.008 m
cable length (Imperial)		≡ 608 ft	= 185.3184 m
cable length (International)		≡ 1/10 nmi	= 185.2 m
cable length (U.S.)		≡ 720 ft	= 219.456 m
chain (Gunter's; Surveyor's)	ch	≡ 66 ft ≡ 4 rods [3]	= 20.1168 m
cubit (H)		≡ Distance from fingers to elbow ≈ 18in	≈ 0.5 m
ell (H)	ell	≡ 45 in [3]	= 1.143 m
fathom	fm	≡ 6 ft [3]	= 1.8288 m
fermi	fm	≡ 1 × 10−15 m [3]	= 1 × 10−15 m
finger		≡ 7/8 in	= 0.022 225 m
finger (cloth)		≡ 4½ in	= 0.1143 m
foot (Benoît)(H)	ft (Ben)		≈ 0.304 799 735 m
foot (Clarke's; Cape)(H)	ft (Cla)		≈ 0.304 797 2654 m
foot (Indian)(H)	ft Ind		≈ 0.304 799 514 m
foot (International)	ft	≡ ⅓ yd = 12 inches	= 0.3048 m
foot (Sear's)(H)	ft (Sear)		≈ 0.304 799 47 m
foot (U.S. Survey)	ft (US)	≡ 1 200/3 937 m [4]	≈ 0.304 800 610 m
french; charriere	F	≡ ⅓ mm	= 3.3 × 10−4 m
furlong	fur	≡ 10 chains = 660 ft = 220 yd [3]	= 201.168 m
geographical mile (H)		≡ 6 082 ft	= 1 853.7936 m
hand		≡ 4 in [3]	= 0.1016 m
inch	in	≡ 1/36 yd = 1/12 ft	= 0.0254 m
league (land)	lea	≡ 3 US Statute miles [5]	= 4 828.032 m
light-day		≡ 24 light-hours	= 2.590 206 837 12 × 1013 m
light-hour		≡ 60 light-minutes	= 1.079 252 8488 × 1012 m
light-minute		≡ 60 light-seconds	= 1.798 754 748 × 1010 m
light-second		≡ Distance light travels in one second in vacuum	= 2.997 924 58 × 108 m
light-year	l.y.	≡ Distance light travels in vacuum in 365.25 days [6]	= 9.460 730 472 5808 × 1015 m
line	ln	≡ 1/12 in [7]	= 0.002 116 m
link (Gunter's; Surveyor's)	lnk	≡ 1/100 ch [3]	= 0.201 168 m
link (Ramsden's; Engineer's)	lnk	≡ 1 ft [3]	= 0.3048 m
mickey		≡ 1/200 in	= 1.27 × 10−4 m
micron	µ		≡ 1 × 10−6 m
mil; thou	mil	≡ 1 × 10−3 in	= 2.54 × 10−5 m
mil (Sweden and Norway)	mil	≡ 10 km	= 10 000 m
mile	mi	≡ 1 760 yd = 5 280 ft = 80 chains	= 1 609.344 m
mile (U.S. Survey)	mi	≡ 5 280 ft (US Survey feet)	= 5 280 × 1 200/3 937 m ≈ 1 609.347 219 m
nail (cloth)		≡ 2¼ in [3]	= 0.057 15 m
nautical league	NL; nl	≡ 3 nmi [3]	= 5 556 m
nautical mile(international)	NM; nmi	≡ 1 852 m [8]	= 1 852 m
nautical mile (Admiralty)	NM (Adm); nmi (Adm)	≡ 6 080 ft	≡ 1 853.184 m
pace		≡ 2.5 ft [3]	= 0.762 m
palm		≡ 3 in [3]	= 0.0762 m
parsec	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 [9]
point (American, English) [10] [11]	pt	≡ 1/72.272 in	≈ 0.000 351 450 m
point (Didot; European) [11] [12]	pt	≡ 1/12 × 1/72 of pied du roi; After 1878: ≡ 5/133 cm	≈ 0.000 375 97 m; After 1878: ≈ 0.000 375 939 85 m
point (PostScript) [10]	pt	≡ 1/72 in	= 0.000 352 7 m
point (TeX) [10]	pt	≡ 1/72.27 in	= 0.000 351 4598 m
quarter		≡ ¼ yd	= 0.2286 m
rod; pole; perch (H)	rd	≡ 16½ ft	= 5.0292 m
rope (H)	rope	≡ 20 ft [3]	= 6.096 m
span (H)		≡ 9 in [3]	= 0.2286 m
spat [13]			≡ 1 × 1012 m
stick (H)		≡ 2 in	= 0.0508 m
pm, stigma, or bicron			≡ 1 × 10−12 m
telegraph mile (H)	mi	≡ 6 087 ft	= 1 855.3176 m
twip	twp	≡ 1/1 440 in	= 1.7638 × 10−5 m
x unit; siegbahn	xu		≈ 1.0021 × 10−13 m [3]
yard (International)	yd	≡ 0.9144 m [14] ≡ 3 ft ≡ 36 in	≡ 0.9144 m

[edit] Area

Area

Name of unit	Symbol	Definition	Relation to SI units
acre (international)	ac	≡ 10 sq ch = 4 840 sq yd	= 4 046.856 4224 m2
acre (U. S. survey)	ac	≡ 10 sq ch = 4 840 sq yd	= 4 046.873 m2 [15]
are	a	≡ 100 m2	= 100 m2
barn	b	≡ 10−28 m2	= 10−28 m2
barony		≡ 4 000 ac	= 1.618 742 568 96 × 107 m2
board	bd	≡ 1 in × 1 ft	= 7.741 92 × 10−3 m2
boiler horsepower equivalent direct radiation	bhp EDR	≡ (1 ft2) (1 bhp) / (240 BTUIT/h)	≈ 12.958 174 m2
circular inch	circ in	≡ π/4 sq in	≈ 5.067 075 × 10−4 m2
circular mil; circular thou	circ mil	≡ π/4 mil2	≈ 5.067 075 × 10−10 m2
cord		≡ 192 bd	= 1.486 448 64 m2
dunam		≡ 1 000 m2	= 1 000 m2
hectare	ha	≡ 10 000 m2	= 10 000 m2
hide		≡ 100 ac	= 4.046 856 4224 × 105 m2
rood	ro	≡ ¼ ac	= 1 011.714 1056 m2
shed		≡ 10−52 m2	= 10−52 m2
square chain	sq ch	≡ 1/10 ac	= 404.685 642 24 m2
square foot	sq ft	≡ 1 ft × 1 ft	= 9.290 304 × 10−2 m2
square inch	sq in	≡ 1 in × 1 in	= 6.4516 × 10−4 m2
square kilometre	km2	≡ 1 km × 1 km	= 106 m2
square link	sq lnk	≡ 1 lnk × 1 lnk	= 4.046 856 4224 × 10−2 m2
square metre (SI unit)	m2	≡ 1 m × 1 m	= 1 m2
square mil; square thou	sq mil	≡ 1 mil × 1 mil	= 6.4516 × 10−10 m2
square mile; section	sq mi	≡ 1 mi × 1 mi	= 2.589 988 110 336 × 106 m2
square rod/pole/perch	sq rd	≡ 1 rd × 1 rd	= 25.292 852 64 m2
square U.S. Survey foot	sq ft	≡ 1 ft (US) × 1 ft (US)	≈ 9.290 341 161 327 49 × 10-2 m2
square U.S. Survey mile	sq mi	≡ 1 mi (US) × 1 mi (US)	≈ 2.589 998 × 106 m2
square yard	sq yd	≡ 1 yd × 1 yd	= 0.836 127 36 m2
stremma		≡ 1 000 m2	= 1 000 m2
township		≡ 36 sq mi (US)	≈ 9.323 994 × 107 m2
yardland		≡ 30 ac	= 1.214 056 926 72 × 105 m2

[edit] Volume

Volume

Name of unit	Symbol	Definition	Relation to SI units
acre foot	ac ft	≡ 1 ac x 1 ft = 43 560 ft3	= 1 233.481 837 547 52 m3
cubic metre (SI unit)	m3	≡ 1 m × 1 m × 1 m	= 1 m3
litre	L	≡ 1 dm3 [16]	= 0.001 m3
lambda	λ	≡ 1 mm3	= 1 × 10−9 m3
drop (metric)		≡ 1/20 mL	= 50.0 × 10−9 m3
minim (Imperial)	min	≡ 1/480 fl oz (Imp) = 1/60 fl dr (Imp)	= 59.193 880 208 3 × 10−9 m3
minim (U.S.)	min	≡ 1/480 US fl oz = 1/60 US fl dr	= 61.611 519 921 875 × 10−9 m3
drop (U.S.) (alt)	gtt	≡ 1/456 US fl oz	≈ 64.854 231 × 10−9 m3
drop (Imperial) (alt)	gtt	≡ 1/1 824 gi (Imp)	≈ 77.886 684 × 10−9 m3
drop (U.S.)	gtt	≡ 1/360 US fl oz	= 82.148 693 22916 × 10−9 m3
drop (medical)		≡ 1/12 ml	= 83.03 × 10−9 m3
drop (Imperial)	gtt	≡ 1/288 fl oz (Imp)	= 98.656 467 013 8 × 10−9 m3
dash (U.S.)		≡ 1/96 US fl oz = ½ US pinch	= 308.057 599 609 375 × 10−9 m3
dash (Imperial)		≡ 1/384 gi (Imp) = ½ pinch (Imp)	= 369.961 751 302 08 3 × 10−9 m3
pinch (U.S.)		≡ 1/48 US fl oz = ⅛ US tsp	= 616.115 199 218 75 × 10−9 m3
pinch (Imperial)		≡ 1/192 gi (Imp) = ⅛ tsp (Imp)	= 739.923 502 60416 × 10−9 m3
fluid scruple (Imperial)	fl s	≡ 1/24 fl oz (Imp)	= 1.183 877 60416 × 10−6 m3
fluid drachm (Imperial)	fl dr	≡ ⅛ fl oz (Imp)	= 3.551 632 8125 × 10−6 m3
fluid dram (U.S.); U.S. fluidram	fl dr	≡ ⅛ US fl oz	= 3.696 691 195 3125 × 10−6 m3
teaspoon (Canadian)	tsp	≡ 1/6 fl oz (Imp)	= 4.735 510 416 × 10−6 m3
teaspoon (U.S.)	tsp	≡ 1/6 US fl oz	= 4.928 921 595 × 10−6 m3
teaspoon (metric)		≡ 5.0 × 10−6 m3	= 5.0 × 10−6 m3
teaspoon (Imperial)	tsp	≡ 1/24 gi (Imp)	= 5.919 388 02083 × 10−6 m3
dessertspoon (Imperial)		≡ 1/12 gi (Imp)	= 11.838 776 0416 × 10−6 m3
tablespoon (Canadian)	tbsp	≡ ½ fl oz (Imp)	= 14.206 531 25 × 10−6 m3
tablespoon (U.S.)	tbsp	≡ ½ US fl oz	= 14.786 764 7825 × 10−6 m3
tablespoon (metric)			≡ 15.0 × 10−6 m3
cubic inch	cu in	≡ 1 in × 1 in × 1 in	= 16.387 064 × 10−6 m3
tablespoon (Imperial)	tbsp	≡ 5/8 fl oz (Imp)	= 17.758 164 0625 × 10−6 m3
pony		≡ 3/4 US fl oz	= 22.180 147 171 875 × 10−6 m3
fluid ounce (Imperial)	fl oz (Imp)	≡ 1/160 gal (Imp)	= 28.413 0625 × 10−6 m3
fluid ounce (U.S.)	US fl oz	≡ 1/128 gal (US)	= 29.573 529 5625 × 10−6 m3
shot		≡ 1 US fl oz	≈ 29.57 × 10−6 m3
jigger		≡ 1½ US fl oz	≈ 44.36 × 10−6 m3
gill (U.S.)	gi (US)	≡ 4 US fl oz	= 118.294 118 25 × 10−6 m3
gill (Imperial); Noggin	gi (Imp); nog	≡ 5 fl oz (Imp)	= 142.065 3125 × 10−6 m3
cup (Canadian)	c (CA)	≡ 8 fl oz (Imp)	= 227.3045 × 10−6 m3
cup (U.S.)	c (US)	≡ 8 US fl oz ≡ 1/16 gal (US)	= 236.588 2365 × 10−6 m3
cup (metric)	c	≡ 250.0 × 10−6 m3	= 250.0 × 10−6 m3
breakfast cup		≡ 10 fl oz (Imp)	= 284.130 625 × 10−6 m3
pint (U.S. fluid)	pt (US fl)	≡ ⅛ gal (US)	= 473.176 473 × 10−6 m3
pint (U.S. dry)	pt (US dry)	≡ 1/64 bu (US lvl) ≡ ⅛ gal (US dry)	= 550.610 471 3575 × 10−6 m3
pint (Imperial)	pt (Imp)	≡ ⅛ gal (Imp)	= 568.261 25 × 10−6 m3
fifth		≡ 1/5 US gal	= 757.082 3568 × 10−6 m3
quart (U.S. fluid)	qt (US)	≡ ¼ gal (US fl)	= 946.352 946 × 10−6 m3
quart (U.S. dry)	qt (US)	≡ 1/32 bu (US lvl) = ¼ gal (US dry)	= 1.101 220 942 715 × 10−3 m3
quart (Imperial)	qt (Imp)	≡ ¼ gal (Imp)	= 1.136 5225 × 10−3 m3
pottle; quartern		≡ ½ gal (Imp) = 80 fl oz (Imp)	= 2.273 045 × 10−3 m3
board-foot	fbm	≡ 144 cu in	= 2.359 737 216 × 10−3 m3
gallon (U.S. fluid; Wine)	gal (US)	≡ 231 cu in	= 3.785 411 784 × 10−3 m3
gallon (U.S. dry)	gal (US)	≡ ⅛ bu (US lvl)	= 4.404 883 770 86 × 10−3 m3
gallon (Imperial)	gal (Imp)	≡ 4.546  09 L	= 4.546 09 × 10−3 m3
beer gallon	beer gal	≡ 282 cu in	= 4.621 152 048 × 10−3 m3
peck (U.S. dry)	pk	≡ ¼ US lvl bu	= 8.809 767 541 72 × 10−3 m3
peck (Imperial)	pk	≡ 2 gal (Imp)	= 9.092 18 × 10−3 m3
bucket (Imperial)	bkt	≡ 4 gal (Imp)	= 0.018 184 36 m3
timber foot		≡ 1 cu ft	= 0.028 316 846 592 m3
cubic foot	cu ft	≡ 1 ft × 1 ft × 1 ft	= 0.028 316 846 592 m3
firkin		≡ 9 gal (US)	= 0.034 068 706 056 m3
bushel (U.S. dry level)	bu (US lvl)	≡ 2 150.42 cu in	= 0.035 239 070 166 88 m3
bushel (Imperial)	bu (Imp)	≡ 8 gal (Imp)	= 0.036 368 72 m3
bushel (U.S. dry heaped)	bu (US)	≡ 1 ¼ bu (US lvl)	= 0.044 048 837 7086 m3
strike (U.S.)		≡ 2 bu (US lvl)	= 0.070 478 140 333 76 m3
strike (Imperial)		≡ 2 bu (Imp)	= 0.072 737 44 m3
kilderkin		≡ 18 gal (Imp)	= 0.081 829 62 m3
sack (U.S.)		≡ 3 bu (US lvl)	= 0.105 717 210 500 64 m3
sack (Imperial); bag		≡ 3 bu (Imp)	= 0.109 106 16 m3
barrel (U.S. dry)	bl (US)	≡ 105 qt (US) = 105/32 bu (US lvl)	= 0.115 628 198 985 075 m3
barrel (U.S. fluid)	fl bl (US)	≡ 31½ gal (US)	= 0.119 240 471 196 m3
coomb		≡ 4 bu (Imp)	= 0.145 474 88 m3
barrel (petroleum)	bl; bbl	≡ 42 gal (US)	= 0.158 987 294 928 m3
barrel (Imperial)	bl (Imp)	≡ 36 gal (Imp)	= 0.163 659 24 m3
hogshead (U.S.)	hhd (US)	≡ 2 fl bl (US)	= 0.238 480 942 392 m3
seam		≡ 8 bu (US lvl)	= 0.281 912 561 335 04 m3
quarter; pail		≡ 8 bu (Imp)	= 0.290 949 76 m3
hogshead (Imperial)	hhd (Imp)	≡ 2 bl (Imp)	= 0.327 318 48 m3
cord-foot		≡ 16 cu ft	= 0.453 069 545 472 m3
butt, pipe		≡ 126 gal (wine)	= 0.476 961 884 784 m3
perch	per	≡ 16½ ft × 1½ ft × 1 ft	= 0.700 841 953 152 m3
cubic yard	cu yd	≡ 27 cu ft	= 0.764 554 857 984 m3
tun		≡ 252 gal (wine)	= 0.953 923 769 568 m3
displacement ton		≡ 35 cu ft	= 0.991 089 630 72 m3
water ton		≡ 28 bu (Imp)	= 1.018 324 16 m3
freight ton		≡ 40 cu ft	= 1.132 673 863 68 m3
wey (U.S.)		≡ 40 bu (US lvl)	= 1.409 562 806 6752 m3
load		≡ 50 cu ft	= 1.415 842 3296 m3
register ton		≡ 100 cu ft	= 2.831 684 6592 m3
last		≡ 80 bu (Imp)	= 2.909 4976 m3
cord (firewood)		≡ 8 ft × 4 ft × 4 ft	= 3.624 556 363 776 m3
cubic fathom	cu fm	≡ 1 fm × 1 fm × 1 fm	= 6.116 438 863 872 m3
acre-inch		≡ 1 ac × 1 in	= 102.790 153 128 96 m3
cubic mile	cu mi	≡ 1 mi × 1 mi × 1 mi	= 4 168 181 825.440 579 584 m3

[edit] Angle

Angle

Name of unit	Symbol	Definition	Relation to SI units
radian (SI unit)	rad	≡ 180°/π	= 1 rad
centesimal second of arc	"	≡ 1 grad/10 000	≈ 1.570 796 µrad
arcsecond	"	≡ 1°/3 600	≈ 4.848 137 µrad
centesimal minute of arc	'	≡ 1 grad/100	≈ 0.157 080 mrad
minute of arc	'	≡ 1°/60	≈ 0.290 888 mrad
angular mil	µ	≡ 2π/6 400 rad	≈ 0.981 748 mrad
grad; gradian; gon	grad	≡ 2π/400 rad = 0.9°	≈ 15.707 963 mrad
degree (of arc)	°	≡ π/180 rad	≈ 17.453 293 mrad
sign		≡ 30°	≈ 0.523 599 rad
octant		≡ 45°	≈ 0.785 398 rad
sextant		≡ 60°	≈ 1.047 198 rad
quadrant		≡ 90°	≈ 1.570 796 rad

[edit] Solid angle

Solid angle

Name of unit	Symbol	Definition	Relation to SI units
steradian	sr		(SI derived unit)

[edit] Mass

Note: see Weight for detail of mass/weight distinction and conversion

Mass

Name of unit	Symbol	Definition	Relation to SI units
kilogram, grave	kg; G		(SI base unit)
electron rest mass, atomic unit of mass	me		≈ 9.109 382 15 × 10−31 ± 45 × 10−39 kg [17]
electronvolt	eV	≡ 1 eV (energy unit) / c2	= 1.7826 × 10-36 kg
unified atomic mass unit	u; AMU		≈ 1.660 538 73 × 10−27 ± 1.3 × 10−36 kg
dalton	Da		≈ 1.660 902 10 × 10−27 ± 1.3 × 10−36 kg
gamma	γ	≡ 1 μg	= 1 μg
point		≡ 1/100 ct	= 2 mg
mite		≡ 1/20 gr	= 3.239 9455 mg
mite (metric)		≡ 1/20 g	= 50 mg
grain	gr	≡ 64.798 91 mg	= 64.798 91 mg
crith			≈ 89.9349 mg
carat (metric)	ct	≡ 200 mg	= 200 mg
carat	kt	≡ 3 1/6 gr	≈ 205.196 548 333 mg
sheet		≡ 1/700 lb av	= 647.9891 mg
scruple (apothecary)	s ap	≡ 20 gr	= 1.295 9782 g
pennyweight	dwt; pwt	≡ 1/20 oz t	= 1.555 173 84 g
dram (avoirdupois)	dr av	≡ 27 11/32 gr	= 1.771 845 195 3125 g
dram (apothecary; troy)	dr t	≡ 60 gr	= 3.887 9346 g
hyl (CGS unit)		≡ 1 gee × 1 g × 1 s2/m	= 9.806 65 g
ounce (avoirdupois)	oz av	≡ 1/16 lb	= 28.349 523 125 g
assay ton (short)	AT	≡ 1 mg × 1 sh tn ÷ 1 oz t	≈ 29.166 667 g
ounce (apothecary; troy)	oz t	≡ 1/12 lb t	= 31.103 4768 g
assay ton (long)	AT	≡ 1 mg × 1 long tn ÷ 1 oz t	≈ 32.666 667 g
mark		≡ 8 oz t	= 248.827 8144 g
pound (troy)	lb t	≡ 5 760 grains	= 0.373 241 7216 kg
pound (avoirdupois)	lb av	≡ 7 000 grains	= 0.453 592 37 kg
pound (metric)		≡ 500 g	= 500 g
clove		≡ 8 lb av	= 3.628 738 96 kg
stone	st	≡ 14 lb av	= 6.350 293 18 kg
hyl (MKS unit)		≡ 1 gee × 1 kg × 1 s2/m	= 9.806 65 kg
quarter (Imperial)		≡ 1/4 long cwt = 2 st = 28 lb av	= 12.700 586 36 kg
slug; geepound	slug	≡ 1 gee × 1 lb av × 1 s2/ft	≈ 14.593 903 kg
bag (Portland cement)		≡ 94 lb av	= 42.637 682 78 kg
short hundredweight; cental	sh cwt	≡ 100 lb av	= 45.359 237 kg
long hundredweight	long cwt or cwt	≡ 112 lb av	= 50.802 345 44 kg
bag (coffee)		≡ 60 kg	= 60 kg
quintal (metric)	q	≡ 100 kg	= 100 kg
wey		≡ 252 lb = 18 st	= 114.305 277 24 kg (variants exist)
long quarter (informal)		≡ ¼ long tn	= 254.011 7272 kg
quarter (informal)		≡ ¼ short tn	= 226.796 185 kg
kip	kip	≡ 1 000 lb av	= 453.592 37 kg
short ton	sh tn	≡ 2 000 lb	= 907.184 74 kg
tonne (mts unit)	t	≡ 1 000 kg	= 1 000 kg
long ton	long tn or ton	≡ 2 240 lb	= 1 016.046 9088 kg
barge		≡ 22½ sh tn	= 20 411.656 65 kg
Zentner	Ztr.		Definitions vary; see [18] and [19]. See also discussion at Talk:Conversion of units#Zentner

In physics, the pound of mass is sometimes written lbm to distinguish it from the pound-force (lbf). It should not be read as the mongrel unit "pound metre".

[edit] Density

The SI unit for density is:

• kilograms per cubic metre (kg/m³)

Metric units outside the SI

• kilograms per litre (kg/L). Water generally has a density around 1 kg/L, making this a convenient unit.
• kilograms per cubic decimeter (kg/dm³)
• grams per millilitre (g/mL),
• grams per cubic centimeter (g/cc or g/cm³).

These are numerically equivalent to kg/L (1 kg/L = 1 kg/dm³ = 1 g/cm³ = 1 g/mL).

In U.S. customary units or Imperial units, the units of density include:

• ounces per cubic inch (oz/cu in)
• pounds per cubic inch (lb/cu in)
• pounds per cubic foot (lb/cu ft)
• pounds per cubic yard (lb/cu yd)
• pounds per gallon (for U.S. or imperial gallons) (lb/gal)
• pounds per U.S. bushel (lb/bu)
• slugs per cubic foot.

[edit] Time

Time, t

Name of unit	Symbol	Definition	Relation to SI units
second	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)	(SI base unit)
Planck time		≡ (Gℏ/c5)½	≈ 1.351 211 868 × 10−43 s
atomic unit of time	au	≡ a0/(α·c)	≈ 2.418 884 254 × 10−17 s
svedberg	S	≡ 10−13 s	= 100 fs
shake		≡ 10−8 s	= 10 ns
sigma		≡ 10−6 s	= 1 μs
jiffy		≡ 1/60 s	= .016 s
jiffy (alternate)		≡ 1/100 s	= 10 ms
helek		≡ 1/1 080 h	= 3.3 s
minute	min	≡ 60 s	= 60 s
milliday	md	≡ 1/1 000 d	= 24 × 60 × 60 / 1 000 s = 86.4 s
moment		≡ 90 s	= 90 s
ke(traditional)		≡ 1/100 d	= 24 × 60 × 60 / 100 s = 864 s = 24 * 60 / 100 min = 14.4 min
quarter (of an hour)	ke	≡ ¼ h = 1/96 d	= 60 × 60 / 4 s = 900 s = 60 / 4 min = 15 min
hour	h	≡ 60 min	= 3 600 s
day	d	≡ 24 h	= 86 400 s
day	d	≡ average time between consecutive midnights	≈ 86 400 s
week	wk	≡ 7 d	= 604 800 s
fortnight		≡ 2 wk	= 1 209 600 s
month (hollow)	mo	≡ 29 d	= 2 505 600 s
month	mo	≡ 30 d	= 2 592 000 s
month (full)	mo	≡ 31 d	= 2 678 400 s
year (Calendar)	a, y, or yr	≡ 365 d	= 31 536 000 s
year (Gregorian)	a, y, or yr	≡ 365.2425 d	= 31 556 952 s
year (Julian)	a, y, or yr	≡ 365.25 d	= 31 557 600 s
sidereal year	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 s
Olympiad		≡ 4 a of 365 d	= 1.2614 × 108 s
lustre; lustrum		≡ 5 a of 365 d	= 1.5768 × 108 s
octaeteris		≡ 8 a of 365 d	= 2.522 88 × 108 s
decade		≡ 10 a of 365 d	= 3.1536 × 108 s
enneadecaeteris; Metonic cycle		≡ 110 mo (hollow) + 125 mo (full) = 19 a of 365 d	= 5.996 16 × 108 s
Callippic cycle		≡ 441 mo (hollow) + 499 mo (full) = 76 a of 365.25 d	= 2.398 3776 × 109 s
century (Calendar)		≡ 100 a of 365 d	= 3.1536 × 109 s
century (Julian)		≡ 100 a of 365.25 d	= 3.155 76 × 109 s
Hipparchic cycle		≡ 4 Callippic cycles - 1 d	= 9.593 424 × 109 s
millennium (Calendar)		≡ 1 000 a of 365 d = 365 000 d	= 3.1536 × 1010 s
millennium (Gregorian)		≡ 1 000 a of 365.2425 d = 356 242.5 d	= 3.155 6952 × 1010 s
millennium (Julian)		365 250} d	= 3.155 76 × 1010 s
Sothic cycle		≡ 1 461 a of 365 d	= 4.607 4096 × 1010 s
generation

[edit] Speed or velocity

Speed

Name of unit	Symbol	Definition	Relation to SI units
metre per second (SI unit)	m/s	≡ 1 m/s	= 1 m/s
foot per hour	fph	≡ 1 ft/h	≈ 8.466 667 × 10−5 m/s
furlong per fortnight		≡ furlong/fortnight	≈ 1.663 095 × 10−4 m/s
inch per minute	ipm	≡ 1 in/min	≈ 4.23 333 × 10−4 m/s
foot per minute	fpm	≡ 1 ft/min	= 5.08 × 10−3 m/s
inch per second	ips	≡ 1 in/s	= 2.54 × 10−2 m/s
kilometre per hour	km/h	≡ 1 km/h	≈ 2.777 778 × 10−1 m/s
foot per second	fps	≡ 1 ft/s	= 3.048 × 10−1 m/s
mile per hour	mph	≡ 1 mi/h	= 0.447 04 m/s
knot	kn	≡ 1 NM/h = 1.852 km/h	≈ 0.514 444 m/s
knot (Admiralty)	kn	≡ 1 NM (Adm)/h = 1.853 184 km/h[citation needed]	= 0.514 773 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	c	≡ 299 792 458 m/s	= 299 792 458 m/s
speed of sound in air	s		≈ 344 m/s at 20 °C, 60% relative humidity [20]
mach	M	≡ 331 m/s[citation needed]	= 331 m/s

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

[edit] Acceleration

Acceleration

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

[edit] Force

Force

Name of unit	Symbol	Definition	Relation to SI units
atomic unit of force		≡ me·α2·c2/a0	≈ 8.238 722 06 × 10−8 N [21]
dyne (cgs unit)	dyn	≡ g·cm/s2	= 10−5 N
milligrave-force, gravet-force	mGf; gf	≡ g × 1 g	= 9.806 65 mN
pound	lb	≡ slug·ft/s2	= 4.448 230 531 N
kilogram-force; 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
newton (SI unit)	N	≡ kg·m/s2	= 1 N
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
sthene (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

[edit] Pressure or mechanical stress

Pressure

Name of unit	Symbol	Definition	Relation to SI units
atmosphere (standard)	atm		≡ 101 325 Pa [22]
atmosphere (technical)	at	≡ 1 kgf/cm2	= 9.806 65 × 104 Pa [22]
bar	bar		≡ 105 Pa
barye (cgs unit)		≡ 1 dyn/cm2	= 0.1 Pa
centimetre of mercury	cmHg	≡ 13 595.1 kg/m3 × 1 cm × g	≈ 1.333 22 × 103 Pa [22]
centimetre of water (4 °C)	cmH2O	≈ 999.972 kg/m3 × 1 cm × g	≈ 98.0638 Pa [22]
foot of mercury (conventional)	ftHg	≡ 13 595.1 kg/m3 × 1 ft × g	≈ 40.636 66 × 103 Pa [22]
foot of water (39.2 °F)	ftH2O	≈ 999.972 kg/m3 × 1 ft × g	≈ 2.988 98 × 103 Pa [22]
inch of mercury (conventional)	inHg	≡ 13 595.1 kg/m3 × 1 in × g	≈ 3.386 389 × 103 Pa [22]
inch of water (39.2 °F)	inH2O	≈ 999.972 kg/m3 × 1 in × g	≈ 249.082 Pa [22]
kilogram-force per square millimetre	kgf/mm2	≡ 1 kgf/mm2	= 9.806 65 × 106 Pa [22]
kip per square inch	ksi	≡ 1 kipf/sq in	≈ 6.894 757 × 106 Pa [22]
micron (micrometre) of mercury	μmHg	≡ 13 595.1 kg/m3 × 1 μm × g ≈ 0.001 torr	≈ 0.133 3224 Pa [22]
millimetre of mercury	mmHg	≡ 13 595.1 kg/m3 × 1 mm × g ≈ 1 torr	≈ 133.3224 Pa [22]
millimetre of water (3.98 °C)	mmH2O	≈ 999.972 kg/m3 × 1 mm × g = 0.999 972 kgf/m2	= 9.806 38 Pa
pascal (SI unit)	Pa	≡ N/m2 = kg/(m·s2)	= 1 Pa [23]
pièze (mts unit)	pz	≡ 1 000 kg/m·s2	= 1 × 103 Pa = 1 kPa
pound per square foot	psf	≡ 1 lbf/ft2	≈ 47.880 25 Pa [22]
poundal per square foot	pdl/sq ft	≡ 1 pdl/sq ft	≈ 1.488 164 Pa [22]
pound per square inch	psi	≡ 1 lbf/in2	≈ 6.894 757 × 103 Pa [22]
short ton per square foot		≡ 1 sh tn × g / 1 sq ft	≈ 95.760 518 × 103 Pa
torr	torr	≡ 101 325/760 Pa	≈ 133.3224 Pa [22]

[edit] Torque

Torque

Name of unit	Symbol	Definition	Relation to SI units
Newton metre (SI unit)	N·m	≡ N × m = kg·m2/s2	= 1 N·m
foot-poundal	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
foot-pound force	ft lbf	≡ g × 1 lb × 1 ft	= 1.355 817 948 331 4004 N·m

[edit] Energy

Energy

Name of unit	Symbol	Definition	Relation to SI units
joule (SI unit)	J	≡ m·N = W·s = V·A·s = kg·m2/s2	= 1 J
electronvolt	eV	≡ e × 1 V	≈ 1.602 177 33 × 10−19 ± 4.9 × 10-26 J
rydberg	Ry	≡ R∞·ℎ·c	≈ 2.179 872 × 10−18 J
hartree, atomic unit of energy	Eh	≡ me·α2·c2 (= 2 Ry)	≈ 4.359 744 × 10−18 J
erg (cgs unit)	erg	≡ 1 g·cm2/s2	= 10−7 J
foot-poundal	ft pdl	≡ 1 lb·ft2/s2	= 4.214 011 009 380 48 × 10−2 J
cubic centimetre of atmosphere; standard cubic centimetre	cc atm; scc	≡ 1 atm × 1 cm3	= 0.101 325 J
inch-pound force	in lbf	≡ g × 1 lb × 1 in	= 0.112 984 829 027 6167 J
foot-pound force	ft lbf	≡ g × 1 lb × 1 ft	= 1.355 817 948 331 4004 J
calorie (20 °C)	cal20 °C		≈ 4.1819 J
calorie (thermochemical)	calth	≡ 4.184 J	= 4.184 J
calorie (15 °C)	cal15 °C	≡ 4.1855 J	= 4.1855 J
calorie (International Table)	calIT	≡ 4.1868 J	= 4.1868 J
calorie (mean)	calmean		≈ 4.190 02 J
calorie (3.98 °C)	cal3.98 °C		≈ 4.2045 J
kilocalorie; large calorie	kcal; Cal	≡ 1 000 calIT	= 4.1868 × 103 J
litre-atmosphere	l atm; sl	≡ 1 atm × 1 L	= 101.325 J
gallon-atmosphere (US)	US gal atm	≡ 1 atm × 1 gal (US)	= 383.556 849 0138 J
gallon-atmosphere (imperial)	imp gal atm	≡ 1 atm × 1 gal (imp)	= 460.632 569 25 J
British thermal unit (thermochemical)	BTUth		≈ 1.054 350 × 103 J
British thermal unit (ISO)	BTUISO	≡ 1.0545 × 103 J	= 1.0545 × 103 J
British thermal unit (63 °F)	BTU63 °F		≈ 1.0546 × 103 J
British thermal unit (60 °F)	BTU60 °F		≈ 1.054 68 × 103 J
British thermal unit (59 °F)	BTU59 °F	≡ 1.054 804 × 103 J	= 1.054 804 × 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 (39 °F)	BTU39 °F		≈ 1.059 67 × 103 J
Celsius heat unit (International Table)	CHUIT	≡ 1 BTUIT × 1 K/°R	= 1.899 100 534 716 × 103 J
cubic foot of atmosphere; standard cubic foot	cu ft atm; scf	≡ 1 atm × 1 ft3	= 2.869 204 480 9344 × 103 J
cubic yard of atmosphere; standard cubic yard	cu yd atm; scy	≡ 1 atm × 1 yd3	= 77.468 520 985 2288 × 103 J
cubic foot of natural gas		≡ 1 000 BTUIT	= 1.055 055 852 62 × 106 J
horsepower-hour	hp·h	≡ 1 hp × 1 h	= 2.684 519 537 696 172 792 × 106 J
kilowatt-hour; Board of Trade Unit	kW·h; B.O.T.U.	≡ 1 kW × 1 h	= 3.6 × 106 J
thermie	th	≡ 1 McalIT	= 4.1868 × 106 J
therm (U.S.)		≡ 100 000 BTU59 °F	= 105.4804 × 106 J
therm (E.C.)		≡ 100 000 BTUIT	= 105.505 585 262 × 106 J
ton of TNT	tTNT	≡ 1 Gcalth	= 4.184 × 109 J
barrel of oil equivalent	bboe	≈ 5.8 × 106 BTU59 °F	≈ 6.12 × 109 J
ton of coal equivalent	TCE	≡ 7 Gcalth	= 29.3076 × 109 J
ton of oil equivalent	TOE	≡ 10 Gcalth	= 41.868 × 109 J
quad		≡ 1015 BTUIT	= 1.055 055 852 62 × 1018 J

[edit] Power

Power

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

[edit] Angular momentum

Action, Angular momentum

Name of unit	Symbol	Definition	Relation to SI units
SI unit	J·s	≡ kg·m2/s	= 1 J·s
atomic unit of action	au	≡ ℏ = ℎ/2π	≈ 1.054 571 596 × 10−34 J·s
cgs unit	erg·s	≡ 10−7 J·s	= 10−7 J·s

[edit] Dynamic viscosity

Dynamic viscosity

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 (cgs unit)	P	≡ 10−1 Pa·s	= 10−1 Pa·s

[edit] Kinematic viscosity

Kinematic viscosity

Name of unit	Symbol	Definition	Relation to SI units
SI unit	m2/s	≡ m2/s	= 1 m2/s
stokes (cgs unit)	St	≡ 10−4 m2/s	= 10−4 m2/s

[edit] Electric current

Electric current

Name of unit	Symbol	Definition	Relation to SI units
ampere (SI base unit)	A	≡ C / s	1 A
esu per second; statampere (cgs unit)	esu/s	≡ (0.1 A·m/s) / c	≈ 3.335 641 × 10−10 A
electromagnetic unit; abampere (cgs unit)	abamp	≡ 10 A	= 10 A

[edit] Electric charge

Electric charge

Name of unit	Symbol	Definition	Relation to SI units
coulomb (SI unit)	C	≡ A·s	= 1 C
atomic unit of charge	au	≡ e	≈ 1.602 176 462 × 10−19 C
statcoulomb; franklin; electrostatic unit (cgs unit)	statC; Fr; esu	≡ (0.1 A·m) / c	≈ 3.335 641 × 10−10 C
abcoulomb; electromagnetic unit (cgs unit)	abC; emu	≡ 10 C	= 10 C
faraday	F	≡ 1 mol × NA·e	≈ 96 485.3383 C

[edit] Electric Dipole

Electric Dipole

Name of unit	Symbol	Definition	Relation to SI units
coulomb metre	C·m	≡ coulomb × metre	= C·m

[edit] Electromotive force

Voltage, Electromotive force

Name of unit	Symbol	Definition	Relation to SI units
volt (SI unit)	V	≡ kg·m2/(A·s3)	= 1 V
abvolt (cgs unit)	abV		≡ 1 × 10−8 V
statvolt (cgs unit)	statV	≡ c· (1 μJ/A·m)	= 299.792 458 V

[edit] Electrical resistance

Electrical resistance

Name of unit	Symbol	Definition	Relation to SI units
ohm (SI unit)	Ω	≡ V/A	= kg·m2/(A2·s3)

[edit] Capacitance

Capacitor's Ability to Store Charge

Name of unit	Symbol	Definition	Relation to SI units
farad	F	amount of capacitance for which a potential difference of one volt results in a static charge of one coulomb

[edit] Inductance

Inductance

Name of unit	Symbol	Definition	Relation to SI units
henry (SI unit)	H	≡	= 1 H

[edit] Magnetic field

also known as "magnetic flux density" and "magnetic induction"

Magnetic field

Name of unit	Symbol	Definition	Relation to SI units
teslas	T	webers per square meter	(SI unit)
amperes/meter	A/m
gauss	G	≡maxwell / cm2	10-4 T [25]

[edit] Magnetic flux

magnetic flux

Name of unit	Symbol	Definition	Relation to SI units
weber	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

[edit] Temperature

Note: see Temperature conversion for more detail

Temperature

Name of unit	Symbol	Definition	Conversion to Kelvin
Kelvin	K	0 K ≡ absolute zero (when an ideal gas would theoretically occupy no space)	1 K
degree centesimal	°C	before 1954, 0 °C ≡ triple point of H2O; after 1954, 0.01 °C ≡ triple point of H2O	[K] ≈ [°C] + 273.15
degree Celsius	°C	0°C ≡ freezing pt. of H2O, 100°C ≡ boiling pt. of H2O at 1 atm	[K] = [°C] + 273.15
degree Rankine	°R; °Ra	0 °R ≡ absolute zero	[K] = [°R] × 5/9
degree Fahrenheit	°F	0 °F ≡ freezing pt. of H2O+NaCl, 180°F between freezing and boiling pt of H2O @ 1atm	[K] = ([°F] + 459.67) × 5/9
degree Delisle	°De		[K] = 373.15 − [°De] × 2/3
degree Newton	°N		[K] = [°N] × 100/33 + 273.15
degree Réaumur	°Ré		[K] = [°Ré] × 5/4 + 273.15
degree Rømer	°Rø		[K] = ([°Rø] − 7.5) × 40/21 + 273.15

[edit] Information entropy

Information entropy

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; 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	B	≡ 8 bits	= 7.655 952 (13) × 10-23 J/K	= 23 bit
kilobyte (decimal)	kB	≡ 1 000 B	= 7.655 952 (13) × 10-20 J/K
kilobyte (kibibyte)	KB; KiB	≡ 1 024 B	= 7.839 695 (13) × 10-20 J/K	= 210 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.

[edit] Radioactivity

Radioactivity

Name of unit	Symbol	Definition	Relation to SI units
Becquerel (SI base unit)	Bq	≡ disintegration per second s-1	= 1 Bq
Rutherford	rd	≡ 1 MBq	= 1 × 106 Bq
curie	Ci	≡ 3.7 × 1010 Bq	= 3.7 × 1010 Bq [26]

[edit] Luminance

Luminance

Name of unit	Symbol	Definition	Relation to SI units
candela per square metre (SI base unit)		≡ cd/m2	= 1 cd/m2
lambert	L	≡ (104/π) cd/m2	≈ 3 183.098 86 cd/m2

[edit] Radioactivity - absorbed dose

Radioactivity - absorbed dose

Name of unit	Symbol	Definition	Relation to SI units
gray	Gy	≡ 1J/kg = 1m2·s-2 [27]	= 1 Gy
rad	rad	≡ 0.01 Gy	= 0.01 Gy

[edit] Radioactivity - equivalent dose

Radioactivity - equivalent dose

Name of unit	Symbol	Definition	Relation to SI units
Sievert (SI base unit)	Sv		= 1 Sv
Röntgen equivalent man	rem	≡ 0.01 Sv	= 0.01 Sv

[edit] Software tools

Home and office computers come with converters in bundled spreadsheet applications or can access free converters via the Internet. Units and measurements can be easily converted using these tools, but only if the units are explicitly defined and the conversion is compatible (e.g., cmHg to kPa).

[edit] Free conversion software

• Units (software), a popular cross-platform command-line utility
• Converter, contextual unit converter for Mozilla Firefox browsers
• Converber, portable application converting utility
• calculla calculla - online web converters
• iMetrix - unit converter for xp
• Unit Converter Add-in for Excel - allow a large selection of unit conversions within the Microsoft Excel spread sheet program.
• uniteasy online scientific unit conversion

[edit] General commercial sources of converters

• Advanced electronic calculators have unit-conversion functionality.
• Spreadsheet programs usually provide conversion functions or formulas or the user can write their own.
• Commercial mathematical, scientific and technical applications often include converters.

[edit] References

[edit] See also

v • d • e Systems of measurement Metric systems International System of Units · metre-kilogram-second · centimetre-gram-second · metre-tonne-second · gravitational system Natural units Geometric systems · Planck · Stoney · "Schrödinger" · Atomic · Electronic · Quantum electrodynamical Conventional systems Astronomical · Electrical · Temperature Customary systems Avoirdupois · Troy · Apothecaries' · English · Imperial · Canadian · US · Danish · Dutch · Finnish · French · German · Irish · Maltese · Norwegian · Scottish · Spanish and Portuguese · Swedish · Polish · Romanian · Russian · Tatar · Hindu · Pegu · Chinese · Japanese · Taiwanese Ancient systems Greek · Roman · Egyptian · Hebrew · Arabic · Mesopotamian · Persian · Indian Other systems Non-standard · Mesures usuelles

[edit] External links

• A dictionary of units of measurement
• NIST: Fundamental physical constants — Non-SI units (PDF)
• British law: Units of measurement regulations 1995
• The Unified Code for Units of Measure
• Units, Symbols, and Conversions XML Dictionary
• Online Conversion Calculators Very extensive list of conversions from-to equvalent units.
• Conversion Tools Variety of conversion tools to convert easily.