Conversion of units

Volume

Volume
Name of unit Symbol Definition Relation to SI units
acre-foot ac ft ≡ 1 ac x 1 ft = 43 560 = 1 233.481 837 547 52
ft3 m3
acre-inch   ≡ 1 ac × 1 in = 102.790 153 128 96
m3
barrel (Imperial) bl (Imp) ≡ 36 gal (Imp) = 0.163 659 24 m3
barrel (petroleum) bl; bbl ≡ 42 gal (US) = 0.158 987 294 928 m3
barrel (U.S. dry) bl (US) ≡ 105 qt (US) = 105/32 = 0.115 628 198 985
bu (US lvl) 075 m3
barrel (U.S. fluid) fl bl (US) ≡ 31½ gal (US) = 0.119 240 471 196 m3
board-foot Fbm ≡ 144 cu in = 2.359 737 216 × 10−3
m3
bucket (Imperial) Bkt ≡ 4 gal (Imp) = 0.018 184 36 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
bushel (U.S. dry level) bu (US ≡ 2 150.42 cu in = 0.035 239 070 166 88
lvl) m3
butt, pipe   ≡ 126 gal (wine) = 0.476 961 884 784 m3
coomb   ≡ 4 bu (Imp) = 0.145 474 88 m3
cord (firewood)   ≡ 8 ft × 4 ft × 4 ft = 3.624 556 363 776 m3
cord-foot   ≡ 16 cu ft = 0.453 069 545 472 m3
cubic fathom cu fm ≡ 1 fm × 1 fm × 1 fm = 6.116 438 863 872 m3
cubic foot cu ft ≡ 1 ft × 1 ft × 1 ft = 0.028 316 846 592 m3
cubic inch cu in ≡ 1 in × 1 in × 1 in = 16.387 064 × 10−6 m3
cubic metre (SI unit) m3 ≡1m×1m×1m = 1 m3
cubic mile cu mi ≡ 1 mi × 1 mi × 1 mi = 4 168 181 825.440
579 584 m3
cubic yard cu yd ≡ 27 cu ft = 0.764 554 857 984 m3
cup (breakfast)   ≡ 10 fl oz (Imp) = 284.130 625 × 10−6 m3
cup (Canadian) c (CA) ≡ 8 fl oz (Imp) = 227.3045 × 10−6 m3
cup (metric) C ≡ 250.0 × 10−6 m3 = 250.0 × 10−6 m3
cup (U.S. customary) c (US) ≡ 8 US fl oz ≡ 1/16 gal = 236.588 2365 × 10−6
(US) m3
cup (U.S. food nutrition c (US) ≡ 240 mL[16] = 2.4×10−4 m3
labeling)
dash (Imperial)   ≡ 1/384 gi (Imp) = ½ = 369.961 751 302 08
pinch (Imp) 3 × 10−9 m3
dash (U.S.)   ≡ 1/96 US fl oz = ½ US = 308.057 599 609
pinch 375 × 10−9 m3
dessertspoon (Imperial)   ≡ 1/12 gi (Imp) = 11.838 776
0416 × 10−6 m3
drop (Imperial) Gtt ≡ 1/288 fl oz (Imp) = 98.656 467 013
8 × 10−9 m3
drop (Imperial) (alt) Gtt ≡ 1/1 824 gi (Imp) ≈ 77.886 684 × 10−9 m3
drop (medical)   ≡ 1/12 ml = 83.03 × 10−9 m3
drop (metric)   ≡ 1/20 mL = 50.0 × 10−9 m3
drop (U.S.) Gtt ≡ 1/360 US fl oz = 82.148 693
22916 × 10−9 m3
drop (U.S.) (alt) Gtt ≡ 1/456 US fl oz ≈ 64.854 231 × 10−9 m3
Fifth   ≡ 1/5 US gal = 757.082 3568 × 10−6
m3
firkin   ≡ 9 gal (US) = 0.034 068 706 056 m3
fluid drachm (Imperial) fl dr ≡ ⅛ fl oz (Imp) = 3.551 632 8125 × 10−6
m3
fluid dram (U.S.); U.S. fl dr ≡ ⅛ US fl oz = 3.696 691 195
fluidram 3125 × 10−6 m3
fluid ounce (Imperial) fl oz ≡ 1/160 gal (Imp) = 28.413 0625 × 10−6 m3
(Imp)
fluid ounce (U.S. US fl oz ≡ 1/128 gal (US) = 29.573 529
customary) 5625 × 10−6 m3
fluid ounce (U.S. food US fl oz ≡ 30 mL[16] = 3×10−5 m3
nutrition labeling)
fluid scruple (Imperial) fl s ≡ 1/24 fl oz (Imp) = 1.183 877
60416 × 10−6 m3
gallon (beer) beer gal ≡ 282 cu in = 4.621 152 048 × 10−3
m3
gallon (Imperial) gal (Imp) ≡ 4.546  09 L = 4.546 09 × 10−3 m3
gallon (U.S. dry) gal (US) ≡ ⅛ bu (US lvl) = 4.404 883 770
86 × 10−3 m3
gallon (U.S. fluid; Wine) gal (US) ≡ 231 cu in = 3.785 411 784 × 10−3
m3
gill (Imperial); Noggin gi (Imp); ≡ 5 fl oz (Imp) = 142.065 3125 × 10−6
nog m3
gill (U.S.) gi (US) ≡ 4 US fl oz = 118.294 118 25 × 10−6
m3
hogshead (Imperial) hhd (Imp) ≡ 2 bl (Imp) = 0.327 318 48 m3
hogshead (U.S.) hhd (US) ≡ 2 fl bl (US) = 0.238 480 942 392 m3
jigger (bartending)   ≡ 1½ US fl oz ≈ 44.36 × 10−6 m3
kilderkin   ≡ 18 gal (Imp) = 0.081 829 62 m3
lambda Λ ≡ 1 mm3 = 1 × 10−9 m3
last   ≡ 80 bu (Imp) = 2.909 4976 m3
litre L ≡ 1 dm3 [17] = 0.001 m3
Load   ≡ 50 cu ft = 1.415 842 3296 m3
minim (Imperial) Min ≡ 1/480 fl oz (Imp) = = 59.193 880 208
1/60 fl dr (Imp) 3 × 10−9 m3
minim (U.S.) Min ≡ 1/480 US fl oz = 1/60 = 61.611 519 921
US fl dr 875 × 10−9 m3
peck (Imperial) Pk ≡ 2 gal (Imp) = 9.092 18 × 10−3 m3
peck (U.S. dry) Pk ≡ ¼ US lvl bu = 8.809 767 541
72 × 10−3 m3
perch Per ≡ 16½ ft × 1½ ft × 1 ft = 0.700 841 953 152 m3
pinch (Imperial)   ≡ 1/192 gi (Imp) = ⅛ = 739.923 502
tsp (Imp) 60416 × 10−9 m3
pinch (U.S.)   ≡ 1/48 US fl oz = ⅛ US = 616.115 199 218
tsp 75 × 10−9 m3
pint (Imperial) pt (Imp) ≡ ⅛ gal (Imp) = 568.261 25 × 10−6 m3
pint (U.S. dry) pt (US ≡ 1/64 bu (US lvl) ≡ ⅛ = 550.610 471
dry) gal (US dry) 3575 × 10−6 m3
pint (U.S. fluid) pt (US fl) ≡ ⅛ gal (US) = 473.176 473 × 10−6 m3
Pony   ≡ 3/4 US fl oz = 22.180 147 171
875 × 10−6 m3
pottle; quartern   ≡ ½ gal (Imp) = 80 fl oz = 2.273 045 × 10−3 m3
(Imp)
quart (Imperial) qt (Imp) ≡ ¼ gal (Imp) = 1.136 5225 × 10−3 m3
quart (U.S. dry) qt (US) ≡ 1/32 bu (US lvl) = ¼ = 1.101 220 942
gal (US dry) 715 × 10−3 m3
quart (U.S. fluid) qt (US) ≡ ¼ gal (US fl) = 946.352 946 × 10−6 m3
quarter; pail   ≡ 8 bu (Imp) = 0.290 949 76 m3
register ton   ≡ 100 cu ft = 2.831 684 6592 m3
sack (Imperial); bag   ≡ 3 bu (Imp) = 0.109 106 16 m3
sack (U.S.)   ≡ 3 bu (US lvl) = 0.105 717 210 500 64
m3
seam   ≡ 8 bu (US lvl) = 0.281 912 561 335 04
m3
Shot   ≡ 1 US fl oz ≈ 29.57 × 10−6 m3
strike (Imperial)   ≡ 2 bu (Imp) = 0.072 737 44 m3
strike (U.S.)   ≡ 2 bu (US lvl) = 0.070 478 140 333 76
m3
tablespoon (Canadian) Tbsp ≡ ½ fl oz (Imp) = 14.206 531 25 × 10−6
m3
tablespoon (Imperial) Tbsp ≡ 5/8 fl oz (Imp) = 17.758 164
0625 × 10−6 m3
tablespoon (metric)   ≡ 15.0 × 10−6 m3
tablespoon (U.S. Tbsp ≡ ½ US fl oz = 14.786 764
customary) 7825 × 10−6 m3
tablespoon (U.S. food Tbsp ≡ 15 mL[16] = 1.5×10−5 m3
nutrition labeling)
teaspoon (Canadian) Tsp ≡ 1/6 fl oz (Imp) = 4.735 510 416 × 10−6
m3
teaspoon (Imperial) Tsp ≡ 1/24 gi (Imp) = 5.919 388
02083 × 10−6 m3
teaspoon (metric)   ≡ 5.0 × 10−6 m3 = 5.0 × 10−6 m3
teaspoon (U.S. customary) Tsp ≡ 1/6 US fl oz = 4.928 921 595 × 10−6
m3
teaspoon (U.S. food Tsp ≡ 5 mL[16] = 5×10−6 m3
nutrition labeling)
timber foot   ≡ 1 cu ft = 0.028 316 846 592 m3
ton (displacement)   ≡ 35 cu ft = 0.991 089 630 72 m3
ton (freight)   ≡ 40 cu ft = 1.132 673 863 68 m3
ton (water)   ≡ 28 bu (Imp) = 1.018 324 16 m3
tun   ≡ 252 gal (wine) = 0.953 923 769 568 m3
wey (U.S.)   ≡ 40 bu (US lvl) = 1.409 562 806 6752
m3

Length

Length
Name of unit Symbol Definition Relation to SI units
ångström Å ≡ 1 × 10−10 m = 0.1 nm
astronomical unit AU ≈ Distance from Earth to Sun ≈ 149 597 871 464 m
barleycorn (H)   ≡ ⅓ in (see note above about = 8.46 × 10−3 m
rounding)
bohr, atomic unit a0 ≡ Bohr radius of hydrogen ≈ 5.291 772
of length 0859 × 10−11 ±
3.6 × 10−20 m
cable length   ≡ 608 ft = 185.3184 m
(Imperial)
cable length   ≡ 1/10 nmi = 185.2 m
(International)
cable length (U.S.)   ≡ 720 ft = 219.456 m
chain (Gunter's; ch ≡ 66 ft ≡ 4 rods [3] = 20.1168 m
Surveyor's)
cubit (H)   ≡ Distance from fingers to elbow ≈ 0.5 m
≈ 18in
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; ft (Cla) ≈ 0.304 797 2654 m
Cape) (H)
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
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 = 2.997 924 58 × 108
 second in vacuum m
light-year l.y. ≡ Distance light travels in = 9.460 730 472
vacuum in 365.25 days [6] 5808 × 1015 m
line ln ≡ 1/12 in [7] = 0.002 116 m
link (Gunter's; lnk ≡ 1/100 ch [3] = 0.201 168 m
Surveyor's)
link (Ramsden's; lnk ≡ 1 ft [3] = 0.3048 m
Engineer's)
metre (SI base m ≡ Distance light travels in 1/299 =1m
unit) 792 458 of a second in vacuum.
[8]

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 mil ≡ 10 km = 10 000 m
Norway)
mile mi ≡ 1 760 yd = 5 280 ft = 80 = 1 609.344 m
chains
mile ≡ 6 082 ft = 1 853.7936 m
(geographical) (H)
mile (telegraph) mi ≡ 6 087 ft = 1 855.3176 m
(H)
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 NM (Adm); ≡ 6 080 ft ≡ 1 853.184 m
(Admiralty) nmi (Adm)
nautical mile NM; nmi ≡ 1 852 m [9] = 1 852 m
(international)
pace   ≡ 2.5 ft [3] = 0.762 m
palm   ≡ 3 in [3] = 0.0762 m
parsec pc Distance of star with parallax ≈ 3.085 677 82 × 1016
shift of one arc second from a ± 6 × 106 m [10]
base of one astronomical unit
pica   ≡ 12 points Dependent on point
measures.
point (American, pt ≡ 1/72.272 in ≈ 0.000 351 450 m
English) [11][12]
point (Didot; pt ≡ 1/12 × 1/72 of pied du roi; ≈ 0.000 375 97 m;
European) [12][13]
After 1878: After 1878:
≡ 5/133 cm ≈ 0.000 375 939 85 m
point (PostScript) pt ≡ 1/72 in = 0.000 352 7 m
[11]

point (TeX) [11] pt ≡ 1/72.27 in = 0.000 351 4598 m

quarter   ≡ ¼ yd = 0.2286 m
rod; pole; perch rd ≡ 16½ ft = 5.0292 m
(H)
rope (H) rope ≡ 20 ft [3] = 6.096 m
span (H)   ≡ 9 in [3] = 0.2286 m
spat [14] ≡ 1 × 1012 m
stick (H)   ≡ 2 in = 0.0508 m
stigma; bicron pm ≡ 1 × 10−12 m
(picometre)
twip twp ≡ 1/1 440 in = 1.7638 × 10−5 m
x unit; siegbahn xu ≈ 1.0021 × 10−13 m [3]
yard yd ≡ 0.9144 m [4] ≡ 3 ft ≡ 36 in ≡ 0.9144 m
(International)

Area

Area
Name of unit Symbol Definition Relation to SI units
acre (international) ac ≡ 10 sq ch = 4 840 sq = 4 046.856 4224 m2
yd
acre (U. S. survey) ac ≡ 10 sq ch = 4 840 sq = 4 046.873 m2 [15]
yd
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 bhp ≡ (1 ft ) (1 bhp) / (240 ≈ 12.958 174 m2
2

direct radiation EDR BTUIT/h)

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 foot (U.S. Survey) sq ft ≡ 1 ft (US) × 1 ft ≈ 9.290 341 161 327
(US) 49 × 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 ≡1m×1m = 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 mile (U.S. Survey) sq mi ≡ 1 mi (US) × 1 mi ≈ 2.589 998 × 106 m2
(US)
square rod/pole/perch sq rd ≡ 1 rd × 1 rd = 25.292 852 64 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

Plane angle

Plane angle
Name of unit Symbol Definition Relation to
SI units
angular mil µ ≡ 2π/6 400 rad ≈ 0.981
748 × 10−3 rad
arcminute ' ≡ 1°/60 ≈ 0.290
888 × 10−3 rad
arcsecond " ≡ 1°/3 600 ≈ 4.848
137 × 10−6 rad
centesimal ' ≡ 1 grad/100 ≈ 0.157
minute of arc 080 × 10−3 rad
centesimal " ≡ 1 grad/10 000 ≈ 1.570
second of arc 796 × 10−6 rad
degree (of ° ≡ π/180 rad = 1/360 of a revolution ≈ 17.453
arc) 293 × 10−3 rad
grad; gradian; grad ≡ 2π/400 rad = 0.9° ≈ 15.707
gon 963 × 10−3 rad
octant   ≡ 45° ≈ 0.785 398
rad
quadrant   ≡ 90° ≈ 1.570 796
rad
radian (SI rad The angle subtended at the center of a circle by = 1 rad
unit) an arc whose length is equal to the circle's radius.
One full revolution encompasses 2π radians.
sextant   ≡ 60° ≈ 1.047 198
rad
sign   ≡ 30° ≈ 0.523 599
rad

Frequency

Frequency
Name of unit Symbol Definition Relation to SI
units
hertz (SI unit) Hz ≡ Number of cycles per second = 1 Hz = 1/s
revolutions per rpm ≡ One unit rpm equals one rotation ≈
minute completed around a fixed axis in one 0.104719755 rad/s
minute of time.
Speed or velocity

Speed
Name of unit Symbol Definition Relation to SI units
foot per hour fph ≡ 1 ft/h ≈ 8.466 667 × 10−5 m/s
foot per fpm ≡ 1 ft/min = 5.08 × 10−3 m/s
minute
foot per fps ≡ 1 ft/s = 3.048 × 10−1 m/s
second
furlong per   ≡ furlong/fortnight ≈ 1.663 095 × 10−4 m/s
fortnight
inch per ipm ≡ 1 in/min ≈ 4.23 333 × 10−4 m/s
minute
inch per ips ≡ 1 in/s = 2.54 × 10−2 m/s
second
kilometre per km/h ≡ 1 km/h ≈ 2.777 778 × 10−1 m/s
hour
knot kn ≡ 1 NM/h = 1.852 km/h ≈ 0.514 444 m/s
knot kn ≡ 1 NM (Adm)/h = 1.853 184 = 0.514 773 m/s
(Admiralty) km/h[citation needed]
mach number M The ratio of the speed of an object Unitless. Actual speed of
moving through a fluid to the sound varies depending on
speed of sound in the same atmospheric conditions. See
medium; typically used as a "speed of sound" below for
measure of aircraft speed. one specific condition.
metre per m/s ≡ 1 m/s = 1 m/s
second (SI
unit)
mile per hour mph ≡ 1 mi/h = 0.447 04 m/s
mile per mpm ≡ 1 mi/min = 26.8224 m/s
minute
mile per mps ≡ 1 mi/s = 1 609.344 m/s
second
speed of light c ≡ 299 792 458 m/s = 299 792 458 m/s
in vacuum
speed of s ≈ 344 m/s at 20 °C, 60%
sound in air relative humidity [23]

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

Flow (volume)

Flow
Name of unit Symbol Definition Relation to SI units
cubic foot per minute CFM ≡ 1 ft3/min = 4.719474432×10−4 m3/s
cubic foot per second ft3/s ≡ 1 ft3/s = 0.028316846592 m3/s
cubic inch per minute in /min ≡ 1 in3/min
3
= 2.7311773 × 10−7 m3/s
cubic inch per second in3/s ≡ 1 in3/s = 1.6387064×10−5 m3/s
cubic metre per second (SI m3/s ≡ 1 m3/s = 1 m3/s
unit)
gallon (U.S. fluid) per day GPD ≡ 1 gal/d = 4.381263638 × 10−8 m3/s
gallon (U.S. fluid) per hour GPH ≡ 1 gal/h = 1.051503273 × 10−6 m3/s
gallon (U.S. fluid) per minute GPM ≡1 = 6.30901964×10−5 m3/s
gal/min
litre per minute LPM ≡ 1 L/min = 1.6 × 10−5 m3/s

Acceleration

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

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 [24]
dyne (cgs unit) dyn ≡ g·cm/s2 = 10−5 N
kilogram-force; kgf; kp; ≡ g × 1 kg = 9.806 65 N
kilopond; grave- Gf
force
kip; kip-force kip; kipf; ≡ g × 1 000 lb = 4.448 221 615
klbf 2605 × 103 N
milligrave-force, mGf; gf ≡g×1g = 9.806 65 mN
gravet-force
newton (SI unit) N A force capable of giving a mass of one = 1 N =
kg an acceleration of one meter per 1 kg·m/s2
second, per second.[25]
ounce-force ozf ≡ g × 1 oz = 0.278 013 850
953 7812 N
pound lb ≡ slug·ft/s2 = 4.448 230 531
N
pound-force lbf ≡ g × 1 lb = 4.448 221 615
 2605 N
2
poundal pdl ≡ 1 lb·ft/s = 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

Solid angle

Solid angle
Name of Symbol Definition Relation to
unit SI units
steradian Sr The solid angle subtended at the center of a sphere of = 1 sr
(SI unit) radius r by a portion of the surface of the sphere
having an area r2. A sphere encompasses 4π sr.[14]

Mass

Notes:

 See Weight for detail of mass/weight distinction and conversion.

 In this table, the unit gee is used to denote standard gravity in order to avoid
confusion with the "g" symbol for grams.
 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".

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

Density
Name of unit Symbol Definition Relation to SI units
gram per millilitre g/mL ≡ g/mL = 1,000 kg/m3
kilogram per cubic metre (SI unit) kg/m3 ≡ kg/m3 = 1 kg/m3
kilogram per litre kg/L ≡ kg/L = 1,000 kg/m3
ounce (avoirdupois) per cubic foot oz/ft3 ≡ oz/ft3 ≈ 1.001153961 kg/m3
ounce (avoirdupois) per cubic inch oz/in3 ≡ oz/in3 ≈ 1.729994044×103 kg/m3
ounce (avoirdupois) per gallon (Imperial) oz/gal ≡ oz/gal ≈ 6.236023291 kg/m3
ounce (avoirdupois) per gallon (U.S. oz/gal ≡ oz/gal ≈ 7.489151707 kg/m3
fluid)
pound (avoirdupois) per cubic foot lb/ft3 ≡ lb/ft3 ≈ 16.01846337 kg/m3
pound (avoirdupois) per cubic inch lb/in3 ≡ lb/in3 ≈ 2.767990471×104 kg/m3
pound (avoirdupois) per gallon (Imperial) lb/gal ≡ lb/gal ≈ 99.77637266 kg/m3
pound (avoirdupois) per gallon (U.S. lb/gal ≡ lb/gal ≈ 119.8264273 kg/m3
fluid)
slug per cubic foot slug/ft3 ≡ slug/ft3 ≈ 515.3788184 kg/m3

Time

Time, t
Name of unit Symbol Definition Relation to SI
units
atomic unit of au ≡ a0/(α·c) ≈ 2.418 884
time 254 × 10−17 s
Callippic cycle   ≡ 441 mo (hollow) + 499 mo (full) = 76 = 2.398 3776 × 109
a of 365.25 d s
century   ≡ 100 a (see below for definition of year = 100 × year
length)
day d = 24 h = 86400 s
day (sidereal) d ≡ Time needed for the Earth to rotate ≈ 86 164.1 s
once around its axis, determined from
successive transits of a very distant
astronomical object across an observer's
meridian (International Celestial
Reference Frame)
decade   ≡ 10 a (see below for definition of year = 10 × year
length)
fortnight   ≡ 2 wk = 1 209 600 s
helek   ≡ 1/1 080 h = 3.3 s
Hipparchic cycle   ≡ 4 Callippic cycles - 1 d = 9.593 424 × 109 s
hour h ≡ 60 min = 3 600 s
jiffy   ≡ 1/60 s = .016 s
jiffy (alternate)   ≡ 1/100 s = 10 ms
ke (quarter of an   ≡ ¼ h = 1/96 d = 60 × 60 / 4 s =
hour) 900 s = 60 / 4 min
 = 15 min
ke (traditional)   ≡ 1/100 d = 24 × 60 × 60 /
100 s = 864 s = 24
* 60 / 100 min =
14.4 min
lustre; lustrum   ≡ 5 a of 365 d = 1.5768 × 108 s
Metonic cycle;   ≡ 110 mo (hollow) + 125 mo (full) = = 5.996 16 × 108 s
enneadecaeteris 6940 d ≈ 19 a
millennium   ≡ 1 000 a (see below for definition of = 1000 × year
year length)
milliday md ≡ 1/1 000 d = 24 × 60 × 60 / 1
000 s = 86.4 s
minute min ≡ 60 s = 60 s
moment   ≡ 90 s = 90 s
month (full) mo ≡ 30 d[20] = 2 592 000 s
month (hollow) mo ≡ 29 d[20] = 2 505 600 s
octaeteris   = 48 mo (full) + 48 mo (hollow) + 3 mo = 2.524 608 × 108 s
(full)[21][22] = 8 a of 365.25 d = 2922 d
Planck time   ≡ (Gℏ/c5)½ ≈ 1.351 211
868 × 10−43 s
second s time of 9 192 631 770 periods of the (SI base unit)
radiation corresponding to the transition
between the 2 hyperfine levels of the
ground state of the caesium 133 atom at
0 K[8] (but other seconds are sometimes
used in astronomy)
shake   ≡ 10−8 s = 10 ns
sigma   ≡ 10−6 s = 1 μs
Sothic cycle   ≡ 1 461 a of 365 d = 4.607
4096 × 1010 s
svedberg S ≡ 10−13 s = 100 fs
week wk ≡7d = 604 800 s
year (Gregorian) a, y, or = 365.2425 d average, calculated from = 31 556 952 s
yr common years (365 d) plus leap years
(366 d) on most years divisible by 4. See
leap year for details.
year (Julian) a, y, or = 365.25 d average, calculated from = 31 557 600 s
yr common years (365 d) plus one leap year
(366 d) every four years
year (sidereal) a, y, or ≡ time taken for Sun to return to the ≈ 365.256 363 d ≈
yr same position with respect to the stars of 31 558 149.7632 s
the celestial sphere
year (tropical) a, y, or ≡ Length of time it takes for the Sun to ≈ 365.242 190 d ≈
yr return to the same position in the cycle 31 556 925 s
of seasons
Where UTC is observed, the length of time units longer than 1 s may increase or decrease by
1 s if a leap second occurs during the time interval of interest.

Pressure or mechanical stress

 Pressure
Name of unit Symbol Definition Relation to SI
units
atmosphere (standard) atm ≡ 101 325 Pa [26]
atmosphere (technical) at ≡ 1 kgf/cm2 = 9.806 65 × 104
Pa [26]
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 [26]
centimetre of water (4 °C) cmH2O ≈ 999.972 kg/m3 × 1 cm × g ≈ 98.0638 Pa [26]
foot of mercury ftHg ≡ 13 595.1 kg/m3 × 1 ft × g ≈ 40.636 66 × 103
(conventional) Pa [26]
foot of water (39.2 °F) ftH2O ≈ 999.972 kg/m3 × 1 ft × g ≈ 2.988 98 × 103
Pa [26]
inch of mercury inHg ≡ 13 595.1 kg/m3 × 1 in × g ≈ 3.386 389 × 103
(conventional) Pa [26]
inch of water (39.2 °F) inH2O ≈ 999.972 kg/m3 × 1 in × g ≈ 249.082 Pa [26]
kilogram-force per square kgf/mm2 ≡ 1 kgf/mm2 = 9.806 65 × 106
millimetre Pa [26]
kip per square inch ksi ≡ 1 kipf/sq in ≈ 6.894 757 × 106
Pa [26]
micron (micrometre) of μmHg ≡ 13 595.1 kg/m3 × 1 μm × g ≈ ≈ 0.133 3224 Pa
[26]
mercury 0.001 torr
millimetre of mercury mmHg ≡ 13 595.1 kg/m3 × 1 mm × g ≈ 1 ≈ 133.3224 Pa [26]
torr
millimetre of water (3.98 mmH2O ≈ 999.972 kg/m3 × 1 mm × g = = 9.806 38 Pa
°C) 0.999 972 kgf/m2
pascal (SI unit) Pa ≡ N/m2 = kg/(m·s2) = 1 Pa [27]
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
[26]

pound per square inch psi ≡ 1 lbf/in2 ≈ 6.894 757 × 103

Pa [26]
poundal per square foot pdl/sq ft ≡ 1 pdl/sq ft ≈ 1.488 164 Pa
[26]

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 [26]

Torque or moment of force

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

Energy, work, or amount of heat

Energy
Name of unit Symbol Definition Relation to SI
units
barrel of oil equivalent bboe ≈ 5.8 × 106 BTU59 °F ≈ 6.12 × 109 J
British thermal unit BTUISO ≡ 1.0545 × 103 J = 1.0545 × 103 J
(ISO)
British thermal unit BTUIT = 1.055 055 852
(International Table) 62 × 103 J
British thermal unit BTUmean ≈ 1.055 87 × 103 J
(mean)
British thermal unit BTUth ≈ 1.054 350 × 103
(thermochemical) J
British thermal unit (39 BTU39 °F ≈ 1.059 67 × 103 J
°F)
British thermal unit (59 BTU59 °F ≡ 1.054 804 × 103 J = 1.054 804 × 103
°F) J
British thermal unit (60 BTU60 °F ≈ 1.054 68 × 103 J
°F)
British thermal unit (63 BTU63 °F ≈ 1.0546 × 103 J
°F)
calorie (International calIT ≡ 4.1868 J = 4.1868 J
Table)
calorie (mean) calmean ≈ 4.190 02 J
calorie calth ≡ 4.184 J = 4.184 J
(thermochemical)
calorie (3.98 °C) cal3.98 °C ≈ 4.2045 J
calorie (15 °C) cal15 °C ≡ 4.1855 J = 4.1855 J
calorie (20 °C) cal20 °C ≈ 4.1819 J
Celsius heat unit CHUIT ≡ 1 BTUIT × 1 K/°R = 1.899 100 534
(International Table) 716 × 103 J
cubic centimetre of cc atm; ≡ 1 atm × 1 cm3 = 0.101 325 J
atmosphere; standard scc
cubic centimetre
cubic foot of cu ft atm; ≡ 1 atm × 1 ft3 = 2.869 204 480
atmosphere; standard scf 9344 × 103 J
cubic foot
cubic foot of natural gas   ≡ 1 000 BTUIT = 1.055 055 852
62 × 106 J
cubic yard of cu yd ≡ 1 atm × 1 yd3 = 77.468 520 985
atmosphere; standard atm; scy 2288 × 103 J
cubic yard
electronvolt eV ≡e×1V ≈ 1.602 177
33 × 10−19 ±
4.9 × 10−26 J
erg (cgs unit) erg ≡ 1 g·cm2/s2 = 10−7 J
foot-pound force ft lbf ≡ g × 1 lb × 1 ft = 1.355 817 948
331 4004 J
foot-poundal ft pdl ≡ 1 lb·ft2/s2 = 4.214 011 009
380 48 × 10−2 J
gallon-atmosphere imp gal ≡ 1 atm × 1 gal (imp) = 460.632 569 25
(imperial) atm J
gallon-atmosphere (US) US gal ≡ 1 atm × 1 gal (US) = 383.556 849
atm 0138 J
hartree, atomic unit of Eh ≡ me·α2·c2 (= 2 Ry) ≈ 4.359
energy 744 × 10−18 J
horsepower-hour hp·h ≡ 1 hp × 1 h = 2.684 519 537
696 172 792 × 106
J
inch-pound force in lbf ≡ g × 1 lb × 1 in = 0.112 984 829
027 6167 J
joule (SI unit) J The work done when a force of = 1 J = 1 m·N =
one newton moves the point of 1 kg·m2/s2
its application a distance of one
meter in the direction of the
force.[25]
kilocalorie; large calorie kcal; Cal ≡ 1 000 calIT = 4.1868 × 103 J
kilowatt-hour; Board of kW·h; ≡ 1 kW × 1 h = 3.6 × 106 J
Trade Unit B.O.T.U.
litre-atmosphere l atm; sl ≡ 1 atm × 1 L = 101.325 J
quad   ≡ 1015 BTUIT = 1.055 055 852
62 × 1018 J
rydberg Ry ≡ R∞·ℎ·c ≈ 2.179
872 × 10−18 J
therm (E.C.)   ≡ 100 000 BTUIT = 105.505 585
262 × 106 J
therm (U.S.)   ≡ 100 000 BTU59 °F = 105.4804 × 106 J
thermie th ≡ 1 McalIT = 4.1868 × 106 J
ton of coal equivalent TCE ≡ 7 Gcalth = 29.3076 × 109 J
ton of oil equivalent TOE ≡ 10 Gcalth = 41.868 × 109 J
ton of TNT tTNT ≡ 1 Gcalth = 4.184 × 109 J

Power or heat flow rate

Power
Name of unit Symbol Definition Relation to SI units
atmosphere-cubic atm ccm ≡ 1 atm × 1 cm3/min = 1.688 75 × 10−3 W
centimetre per minute
atmosphere-cubic atm ccs ≡ 1 atm × 1 cm3/s = 0.101 325 W
centimetre per second
atmosphere-cubic foot atm cfh ≡ 1 atm × 1 cu ft/h = 0.797 001 244 704
per hour W
atmosphere-cubic foot atm·cfm ≡ 1 atm × 1 cu ft/min = 47.820 074 682 24
per minute W
atmosphere-cubic foot atm cfs ≡ 1 atm × 1 cu ft/s = 2.869 204 480
per second 9344 × 103 W
BTU (International BTUIT/h ≡ 1 BTUIT/h ≈ 0.293 071 W
Table) per hour
BTU (International BTUIT/min ≡ 1 BTUIT/min ≈ 17.584 264 W
Table) per minute
BTU (International BTUIT/s ≡ 1 BTUIT/s = 1.055 055 852
Table) per second 62 × 103 W
calorie (International calIT/s ≡ 1 calIT/s = 4.1868 W
Table) per second
foot-pound-force per ft lbf/h ≡ 1 ft lbf/h ≈ 3.766 161 × 10−4
hour W
foot-pound-force per ft lbf/min ≡ 1 ft lbf/min = 2.259 696 580 552
minute 334 × 10−2 W
foot-pound-force per ft lbf/s ≡ 1 ft lbf/s = 1.355 817 948 331
second 4004 W
horsepower (boiler) bhp ≈ 34.5 lb/h × 970.3 BTUIT/lb ≈ 9.810 657 × 103
W
horsepower hp ≡ 75 kp·m/s = 736 W
(European electrical)
horsepower (Imperial hp ≡ 746 W = 746 W
electrical)
horsepower (Imperial hp ≡ 550 ft lbf/s = 745.699 871 582
mechanical) 270 22 W
horsepower (metric) hp ≡ 75 m kgf/s = 735.498 75 W
litre-atmosphere per L·atm/min ≡ 1 atm × 1 L/min = 1.688 75 W
minute
litre-atmosphere per L·atm/s ≡ 1 atm × 1 L/s = 101.325 W
second
lusec lusec ≡ 1 L·µmHg/s [14] ≈ 1.333 × 10−4 W
poncelet p ≡ 100 m kgf/s = 980.665 W
square foot equivalent sq ft EDR ≡ 240 BTUIT/h ≈ 70.337 057 W
direct radiation
ton of air conditioning   ≡ 1 t ice melted / 24 h ≈ 3 504 W
ton of refrigeration   ≡ 1 BTUIT × 1 lng tn/lb ÷ 10 ≈ 3.938 875 × 103
(Imperial) min/s W
ton of refrigeration   ≡ 1 BTUIT × 1 sh tn/lb ÷ 10 ≈ 3.516 853 × 103
(IT) min/s W
watt (SI unit) W The power which in one second = 1 W = 1 J/s =
of time gives rise to one joule of 1 N·m/s =
energy.[25] 1 kg·m2/s3

Action

Action
Name of unit Symbo Definition Relation to SI units
l
atomic unit of au ≡ ℏ = ℎ/2π ≈ 1.054 571 68 × 10−34 J·s[28]
action
Dynamic viscosity

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

Kinematic viscosity

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

Electric current

Electric current
Name of unit Symbol Definition Relation to SI
units
ampere (SI base A ≡ The constant current needed to =1A
unit) 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.[8]
electromagnetic abamp ≡ 10 A = 10 A
unit; abampere (cgs
unit)
esu per second; esu/s ≡ (0.1 A·m/s) / c ≈
statampere (cgs 3.335641×10−10 A
unit)

Electric charge

Electric charge
Name of unit Symbol Definition Relation to SI
units
abcoulomb; abC; emu ≡ 10 C = 10 C
electromagnetic unit (cgs
unit)
atomic unit of charge Au ≡e ≈ 1.602 176
462 × 10−19 C
coulomb (SI unit) C ≡ The amount of electricity = 1 C = 1 A·s
carried in one second of time by
one ampere of current.[25]
faraday F ≡ 1 mol × NA·e ≈ 96 485.3383
C
statcoulomb; franklin; statC; Fr; ≡ (0.1 A·m) / c ≈ 3.335
electrostatic unit (cgs esu 641 × 10−10 C
unit)

Electric dipole

Electric dipole
Name of unit Symbo Definition Relation to SI units
l
atomic unit of electric dipole ea0   ≈ 8.478 352 81 × 10−30 C·m[29]
moment

Electromotive force, electric potential difference

Voltage, electromotive force

Name of Symbol Definition Relation to SI
unit units
abvolt abV ≡ 1 × 10−8 V = 1 × 10−8 V
(cgs unit)
statvolt statV ≡ c· (1 μJ/A·m) = 299.792 458 V
(cgs unit)
volt (SI V The difference in electric potential across two = 1 V = 1 W/A =
unit) points along a conducting wire carrying one 1 kg·m2/(A·s3)
ampere of constant current when the power
dissipated between the points equals one watt.[25]

Electrical resistance

Electrical resistance
Name Symbol Definition Relation to SI
of unit units
ohm (SI Ω The resistance between two points in a conductor = 1 Ω = 1 V/A =
unit) when one volt of electric potential difference, 1 kg·m2/(A2·s3)
applied to these points, produces one ampere of
current in the conductor.[25]

Capacitance

Capacitor's ability to store charge

 Name Symbol Definition Relation to SI
of unit units
farad F The capacitance between two parallel plates that = 1 F = 1 C/V = 1
(SI unit) results in one volt of potential difference when A2·s4/(kg·m2)
charged by one coulomb of electricity.[25]

Magnetic flux

magnetic flux
Name of Symbol Definition Relation to SI
unit units
maxwell Mx ≡ 10−8 Wb[30] = 1 × 10−8 Wb
(CGS unit)
weber (SI Wb Magnetic flux which, linking a circuit of one = 1 Wb = 1 V·s =
unit) turn, would produce in it an electromotive force 1 kg·m2/(A·s2)
of 1 volt if it were reduced to zero at a uniform
rate in 1 second.[25]

Magnetic flux density

What physicists call Magnetic field is called Magnetic flux density by electrical engineers and
magnetic induction by applied mathematicians and electrical engineers.

Name of unit Symbol Definition Relation to SI units

gauss (CGS unit) G ≡ Mx/cm2 = 10−4 T = 1 × 10−4 T [31]
tesla (SI unit) T ≡ Wb/m2 = 1 T = 1 Wb/m2 = 1 kg/(A·s2)

Inductance

Inductance
Name Symbol Definition Relation to SI
of unit units
henry H The inductance of a closed circuit that produces one = 1 H = 1 Wb/A
(SI unit) volt of electromotive force when the current in the = 1 kg·m2/(A·s)2
circuit varies at a uniform rate of one ampere per
second.[25]

Temperature

For more details on this topic, see Temperature conversion.

Temperature
Name of Symbo Definition Conversion to
unit l kelvin
degree °C °C = K − 273.15. A unit of °C is the same size [K] = [°C] +
Celsius as a unit of K; however, their numerical values 273.15
differ as the zero point of Celsius is set at
273.15 K (the ice point).[8]
degree °De [K] = 373.15 −
Delisle [°De] × 2/3
degree °F 0 °F ≡ freezing pt. of H2O+NaCl, 180°F [K] = ([°F] +
Fahrenheit between freezing and boiling pt of H2O @ 1atm 459.67) × 5/9
degree °N [K] = [°N] ×
Newton 100/33 + 273.15
degree °R; °Ra 0 °R ≡ absolute zero [K] = [°R] × 5/9
Rankine
degree °Ré [K] = [°Ré] × 5/4
Réaumur + 273.15
degree °Rø [K] = ([°Rø] −
Rømer 7.5) × 40/21 +
273.15
kelvin (SI K ≡ 1/273.16 of the thermodynamic temperature 1K
base unit) of the triple point of water.[8]

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; ≡ ln(10) × = 3.179 065 3(53) × 10−23
Hart kB J/K
nibble ≡ 4 bits = 3.827 976 0(64) × 10−23 = 22 bit
J/K
byte B ≡ 8 bits = 7.655 952 (13) × 10−23 J/K = 23 bit
kilobyte kB ≡ 1 000 B = 7.655 952 (13) × 10−20 J/K
(decimal)
kilobyte KB; KiB ≡ 1 024 B = 7.839 695 (13) × 10−20 J/K = 210 bit
(kibibyte)

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.

Luminous intensity

The candela is the preferred nomenclature for the SI unit.

Luminous intensity
Name of unit Symbol Definition Relation
to SI units
candela (SI cd The luminous intensity, in a given direction, of a = 1 cd
base unit); source that emits monochromatic radiation of
candle frequency 540 × 1012 hertz and that has a radiant
 intensity in that direction of 1/683 watt per
steradian.[8]
candlepower cp ≡ cd The use of candlepower as a unit is = 1 cd
(new) discouraged due to its ambiguity.
candlepower cp Varies and is poorly reproducible.[32] ≈ 0.981 cd
(old, pre-1948) Approximately 0.981 cd.[14]

Luminance

Luminance
Name of unit Symbol Definition Relation to SI units
candela per square foot cd/ft2 ≡ cd/ft2 ≈ 10.763910417 cd/m2
candela per square inch cd/in2 ≡ cd/in2 ≈ 1,550.0031 cd/m2
2
candela per square metre (SI unit); nit cd/m ≡ cd/m2 = 1 cd/m2
(deprecated[14])
footlambert fL ≡ (1/π) cd/ft2 ≈ 3.4262590996 cd/m2
lambert L ≡ (104/π) ≈
cd/m2 3,183.0988618 cd/m2
stilb (CGS unit) sb ≡ 104 cd/m2 ≈ 1 × 104 cd/m2

Luminous flux

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

Illuminance

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

Radiation - source activity

Radioactivity
Name of unit Symbo Definition Relation to SI units
l
becquerel (SI Bq ≡ Number of disintegrations per second = 1 Bq = 1/s
unit)
curie Ci ≡ 3.7 × 1010 Bq = 3.7 × 1010 Bq [33]
rutherford (H) rd ≡ 1 MBq = 1 × 106 Bq
Please note that although becquerel (Bq) and hertz (Hz) both ultimately refer to the same SI
base unit (s−1), Hz is used only for periodic phenomena, and Bq is only used for stochastic
processes associated with radioactivity.[34]

Radiation - exposure

Radiation - exposure
Name of Symbo Definition Relation to SI units
unit l
roentgen R 1 R ≡ 2.58 × 10−4 C/kg[30] = 2.58 × 10−4 C/kg

The roentgen is not a SI unit and the NIST strongly discourages its continued use.[35]

Radiation - absorbed dose

Radiation - absorbed dose

Name of unit Symbo Definition Relation to SI units
l
gray (SI unit) Gy ≡ 1 J/kg = 1 m2/s2 [36] = 1 Gy
rad rad ≡ 0.01 Gy[30] = 0.01 Gy

Radiation - equivalent dose

Radiation - equivalent dose

Name of unit Symbol Definition Relation to SI units
Röntgen equivalent man rem ≡ 0.01 Sv = 0.01 Sv
sievert (SI unit) Sv ≡ 1 J/kg[34] = 1 Sv
 GAMBAR DAN BAGIAN-BAGIAN DARI DOUBLE PIPE HE DAN SHELL & TUBE
HE

A.Double Pipe Heat Exchanger

1. Reliable Closures for design pressures up to 15,000 psi (1055 kg/cm2)

2. Independent tubesheets for high-temperature differences, thermal shock and cycling.
3. External Split Rings.
4. All connections on the same end for ease of piping.
5. Moveable Support Brackets with slots for shell expansion.
6. Durable all Welded baffle cage construction.
7. All Bolting is external.
 8. U-bend

B.Shell And Tube Heat Exchanger

Shell and Tube Heat Exchanger adalah jenis Heat Exchanger yang paling umum dipergunakan pada
proses Revinary, Oil and Gas dan Petrochemical. Dalam hal design Shell and Tube Heat Exchanger
(STHE), standar yang dipakai adalah ASME Section VIII dan TEMA Class R, atau API 660. Ada dua
sisi utama dalam design STHE, Shell Side dan Tube Side. Berdasarkan konstruksinya, STHE dapat
dibagi atas beberapa type, masing masing type diberi kode berdasarkan kombinasi type Front Head,
Shell, dan Rear Head.

Tabel berikut adalah type type Head dan Shell yang dimaksud.
Karakteristik masing masing type dari Shell and Tube tersebut digambarkan pada tabel berikut:

Setelah mengetahui karateristik dari masing masing type shell and tube heat exchanger, selanjutnya
design didasarkan atas keperluan atau servicenya. Design yang komplex biasanya menimbulkan biaya
yang lebih mahal dan perawatan yang lebih sulit sehingga biasanya hanya digunakan untuk keperluan
yang tidak memungkinkan penggunaan yang lebih simpel.
 1. Fixed TubeSheet atau Fixed Head (Type L, M, atau N)

Pada type ini kedua tubsheet dilaskan ke shell membentuk sebuah Box, oleh karena itu terkadang type
ini disebut Box-type Exchanger. Karena tube bundle tidak dapat dilepaskan maka pembersihan bagian
luar pipa dilakukan dengan metoda chemical. Penggunaan fixed tubesheer terbatas, dimana fluida
yang melewati shell side harus benar benar bebas dari kotoran, fluida yang tidak bebas dari kotoran
dimungkinkan mengalir melalui tube side.

Di sini tidak memungkinkan melepaskan dan mengganti tube bundle tanpa memotong shell, akan
tetapi penggantian tube secara individual dapat dilakukan dengan menggunakan spesial tube cutters
dan extractors. Pada kontruksinya shell barrel dan tubesheet harus dibuat dari metal yang dapat
dilaskan secara langsung antara satu dengan lainya seperti steel - steel, tidak dapat dilakukan dengan
steel - aluminium ataupun steel -brass.

Altrnative untuk mengatasi persoalan incompatible metal tersebut mungkin dapat dilakukan dengan
melaskan flange pada masing masing ujung shell dengan material yang sama dengan shell, dan
kemudian bolting dengan tubesheet dengan menggunakan gasket yang sesuai.Fixed Tubesheet
Exchanger memiliki kelebihan yang penting yaitu tidak adanya internal joint sehingga sumber sumber
kebocoran dari fluid yang satu ke yang lain dapat diminimalisir.

2. U Tube atau Hairpin (type U)

Type U Tube hanya memiliki satu tubesheet dengan masing masing tube bisa dilepaskan dari shell,
dilain hal juga sangat memungkinkan untuk memindahkan tubeside dan shell side secara
terpisah.Bagian permukaan luar dan permukaan dalam tube dapat dibersihkan dengan metode
chemical. Pada type ini, fluida yang malewati tube side musti fluida yang bebas dari kotoran, fluida
yang tidak bebas kotoran dimungkinkan untuk melewati shell side.
Meskipun U tube dibentuk dari tube yang masing masing identik, akan tetapi terdapat masalah yang
essensial dimana hanya tube dengan radius arc atau yang bagian tepi yang dimunginkan untuk diganti
jika terjadi kebocoran, sedangkan untuk tube yang terkurung dibagian dalam musti di Plug.

3. Split-backing-ring Floating Head(Type S)

Satu tubesheet fix dengan baik pada shell dan tubesheet satunya terapung, dan dimungkinkan
untukmemindahkan secara terpisah antara shell side dan tube side, serta seluruh tube bundle dapat
dilepas. Untuk memisahkan antara fluida pada shell dengan fluida yang melewati tube side, maka
dipergunakan flanged cover yang dibautkan pada split backing ring pada sisi lain tubesheet.Akses ke
tube end pada stationary end hanya dapat dilakukan dengan melepaskan head cover, sedangkan akses
ke tube end pada floating head end dilakukan dengan melepas shell cover, split back ring dan floating
head cover.Ada internal joint pada type ini sehingga membutuhkan design yang sangat hati hati dan
cermat.

4. Pull through floating head (Type T)

Pada konstruksinya, Pull through floating head mirip dengan type split backing ring, akan tetapi pada
pull through floating head covernya dibautkan secara langsung pada floating tubesheet.Kelebihan tipe
ini adalah, memungkinkan untuk melepas tube bundle tampa harus melepaskan shell dan head cover.

5. Packed Lantern ring floating head (Type W)

Packing ring dipasang antara sisi luar floating tubesheet dengan sisi rear head flange
untukmenetapkan pemisah antara fluida yang mengalir melalui shell side dengan fluidayangmelalui
tube side.Pemakaian type ini terbatas hanya pada non-lethal service dan untuk tekanan yang rendah.
Maximum operational temperatur adalah 200 degC, dan maximum operational pressure dapat
dikategorikan sebagai berikut.

**** Shell ID (mm) ………………………….. Maximum Pressure (Bar) *****

600 kebawah ……………………………………. 20

lebih dari 600 hingga 1060 ……………………… 10

lebih dari1060hingga 1525 ……………………. 5

 s

6. Outside Packed floating head(Type P)

Untuk memasukkan fluida dari tube side ke floating head, salah satu silindrical barrel (Skirt) dilaskan
pada sisi luar floating tubesheet, sementara lainya ditetapkan dengan sebuah slip on backing flange
dan flat cover.

Backing flange dipasang dengan sebuah split shear ring yang ditempatkan dalam celah pada skirt,
keberadaan split shear ring memungkinkan bagi flange dan cover untuk dilepas.
Tekanan dan temperatur pada shell side terbatas pada 20 bar dan 300 degC.
 7. Kettle type ReBoiler (type K)

Kettle type Reboiler adalah spesial untuk aplikasi U Tube dan Pull Through. Terdapat vapor space
yang kalkulasinya bergantung pada kuantitas vapor, density dan jumlah vapor yang keluar melalui
nozzle, akan tetapi pada kasus yang umum biasanya satu hingga tiga kali diameter silinder dan
minimal 225 mm. type ini terkadang juga menggunakan dry pipe dan demister pad. Penguapan pada
tipe ini terbatas hanya hingga 80% dari liquid yang diproses.

8. Double bundle Vaporizer

Double type ini adalah spesial design non-TEMA dan cocok dipergunakan untuk penguapan liquid
pada temperatur yang rendah. Meskipun dapat dipenuhi dengan single bundle, akan tetapi spesial
design diperlukan untuk mencegah pembekuan kondensate.

Bundle bagian bawah berperan sebagai kettle yang memanaskan fluida dalam shell dan pendinginan
terjadi pada fluida pada tube side, sementara itu bundle bagian atas berperan menurunkan kembali
temperatur fluida dapam shell dan menyerap panasnya untuk menguapkan fluida dingin pada tibe side
pada bundle atas ini.

9. Bayonat tube

Pada type ini, tube bagian luar, tuab bagian dalam dan shell side dapa dilepaskan secara bebas. Type
ini cocok untuk perbedaan temperatur yang extrim antara kedua fluda di shell side dan tube side. Free
end masing masing pipa bagian luar di seal ke sebuah cover.
Shell side biasanya dilengkapi dengan buffle seperti halnya type lain, akan tetapi untuk ukuran shell
vertikal yang relative pendek kadang tidak diperlukan adanya buffle.

Secara garis besarnya ada dua Tahap Detail Design untuk Shell and Tube Heat Exchanger, Tahap
pertama adalah Thermal Design dan selanjutnya diteruskan dengan Mechanical Design. Output atau
hasil yang diperoleh pada Thermal design akan menjadi data input untuk Mechanical design.
 Tugas Perancangan Alat Penukar Panas

TABEL KONVERSI

GAMBAR DAN BAGIAN-BAGIAN DARI

DOUBLE PIPE HE DAN SHELL & TUBE HE

Oleh :

KESNI SAVITRI
0807121210

PROGRAM STUDI TEKNIK KIMIA S1

FAKULTAS TEKNIK

UNIVERSITAS RIAU

PEKANBARU

2011