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Conversion of units refers to conversion factors between different units of measurement for the same quantity.
Contents - 1 Techniques
- 2 Rounding of results
- 3 Tables of conversion factors
- 3.1 Legend
- 3.2 Length
- 3.3 Area
- 3.4 Volume
- 3.5 Angle
- 3.6 Solid angle
- 3.7 Mass
- 3.8 Time
- 3.9 Speed
- 3.10 Acceleration
- 3.11 Force
- 3.12 Pressure or mechanical stress
- 3.13 Energy, work, or heat
- 3.14 Power
- 3.15 Angular momentum
- 3.16 Electric current
- 3.17 Electric charge
- 3.18 Electromotive force
- 3.19 Electrical resistance
- 3.20 Dynamic viscosity
- 3.21 Kinematic viscosity
- 3.22 Information entropy
- 3.23 Temperature
- 4 Software tools
- 4.1 Free conversion software
- 4.2 General commercial sources of converters
- 5 References
- 6 See also
- 7 External links
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[edit] Techniques
The simplest way to convert from one unit to another is to carry through the units themselves in the mathematical operation. To illustrate this process, consider the following examples.
Suppose one wishes to convert 6 feet into metres. Consulting the table below and finding that one foot is exactly 0.3048 metre, one can now perform the mathematical conversion:
- 6 ft × 0.3048 m/ft = 1.8288 m
Notice that the "foot" units canceled out, leaving only metres, the desired result. (Since 0.3048 metre per foot have infinite precision, the precision of the answer is determined by the precision of the 6 ft figure; if, for example, you are defining the fathom, expressing it with 5 significant figures is correct. But if the 6 ft figure is a measurement, the result needs to be rounded appropriately.)
Say a person's height is 183 centimetres, and one wishes to convert this into inches:
- 183 cm / (2.54 cm/in) = 72.0 in
To check the answer, the result can be converted back into feet:
- 72 in / (12 in/ft) = 6.0 feet
which confirms the earlier result.
Multiple units can be manipulated in the same fashion:
- 7 mi/s × 1.609344 km/mi × 3600 s/h = 40,000 km/h
Thus, Earth's escape velocity is about 7 miles per second, or 40,000 kilometres per hour. Notice that since the calculation started with one significant figure (the 7), the answer also has one significant figure (the 4 in 40,000).
Deciding whether to multiply or divide is determined by looking at the units and deciding which ones it is desired to "get rid" of. In the conversion just above, if one had divided by 3600 s/h instead of multiplying, the result would have come out in kilometre-hours per square second, clearly an incorrect and meaningless result.
Why does it work? Notice that because the numerator and denominator describe the same quantity, the factor is equivalent to the number 1. Therefore, multiplication by this factor does not change the measured quantity, only its units.
[edit] Rounding of results
An important thing to remember is that the process of making a conversion cannot produce a more precise result than that with which one started. While many of the conversion factors given in the tables below are exact, and others, while not exact, contain many significant digits, not all the numbers resulting from performing calculations on a calculator or with pencil and paper are meaningful.
After using these conversion factors, be sure to round off the results appropriately. See significant figures for more details on rounding correctly.
[edit] Tables of conversion factors
[edit] Legend
Legend ≡ | definition |
= | exactly equal to |
≈ | approximately equal to |
(digits) | indicates the digits repeat infinitely |
[edit] Length
Length, l Name of unit | Symbol | Definition | Relation to SI units |
ångström | Å | | ≡ 1×10−10 m = 0.1 nm |
astronomical unit | AU | Mean distance from Earth to the Sun | = 149 597 870.691 ± 0.030 km |
atomic unit of length | au[citation needed] | ≡ a0 | ≈ 5.291 772 083×10−11 ± 19×10−20 m |
barley corn | | ≡ 1/3 in | ≈ 8.466 667 mm |
Bohr radius | a0; b | ≡ α/(4πR∞) | ≈ 5.291 772 083×10−11 ± 19×10−20 m |
cable length (Imperial) | | ≡ 608 ft | = 185.3184 m |
cable length (International) | | ≡ 1/10 NM | = 185.2 m |
cable length (U.S.) | | ≡ 720 ft | = 219.456 m |
calibre | cal | ≡ 1 in | = 25.4 mm |
chain (Gunter's; Surveyor's) | ch | ≡ 66.0 ft (4 rods) | = 20.1168 m |
chain (Ramsden's; Engineer's) | ch | ≡ 100 ft | = 30.48 m |
cubit | | ≡ 18 in | = 0.4572 m |
ell | ell | ≡ 45 in | = 1.143 m |
fathom | fm | ≡ 6 ft | = 1.8288 m |
≈ 1/1000 NM | = 1.852 m |
fermi | fm | ≡ 1×10−15 m | = 1×10−15 m |
finger | | ≡ 7/8 in | = 22.225 mm |
finger (cloth) | | ≡ 4 ½ in | = 0.1143 m |
foot (Benoît) | ft (Ben) | | ≈ 0.304 799 735 m |
foot (Clarke's; Cape) | ft (Cla) | | ≈ 0.304 797 265 4 m |
foot (Indian) | ft Ind | | ≈ 0.304 799 514 m |
foot (International) | ft | ≡ 1/3 yd | = 0.3048 m |
foot (Sear's) | ft (Sear) | | ≈ 0.304 799 47 m |
foot (U.S. Survey) | ft (US) | ≡ 1200/3937 m [1] | ≈ 0.304 800 610 m |
furlong | fur | ≡ 660 ft (10 chains) | = 201.168 m |
geographical mile | mi | ≡ 6082 ft | = 1853.7936 m |
hand | | ≡ 4 in | = 0.1016 m |
inch | in | ≡ 1/36 yd | = 25.4 mm |
league | lea | ≡ 3 mi | = 4828.032 m |
light-day | | ≡ 24 light-hours | = 2.590 206 837 12×1013 m |
light-hour | | ≡ 60 light-minutes | = 1.079 252 848 8×1012 m |
light-minute | | ≡ 60 light-seconds | = 1.798 754 748×1010 m |
light-second | | | ≡ 2.997 924 58×108 m |
light-year | l.y. | ≡ c0 × 86 400 × 365.25 | = 9.460 730 472 580 8×1015 m |
line | ln | ≡ 1/12 in (Klein 1988, 63) | ≈ 2.116 667 mm |
link (Gunter's; Surveyor's) | lnk | ≡ 1/100 ch | = 0.201 168 m |
link (Ramsden's; Engineer's) | lnk | ≡ 1 ft | = 0.3048 m |
metre (SI base unit) | m | ≡ 1 m | = 1 m |
mickey | | ≡ 1/200 in | = 1.27×10−4 m |
micron | µ | | ≡ 1.000×10−6 m |
mil; thou | mil | ≡ 1.000×10−3 in | = 2.54×10−5 m |
mil (Sweden and Norway) | mil | ≡ 10 km | = 10000 m |
mile | mi | ≡ 1760 yd = 5280 ft | = 1609.344 m |
mile (U.S. Survey) | mi | ≡ 5280 ft (US) | = 5280 × 1200/3937 m ≈ 1609.347 219 m |
nail (cloth) | | ≡ 2 ¼ in | = 57.15 mm |
nautical league | NL; nl | ≡ 3 NM | = 5556 m |
nautical mile | NM; nmi | ≡ 1852 m | ≡ 1852 m |
nautical mile (Admiralty) | NM (Adm); nmi (Adm) | ≡ 6080 ft | = 1853.184 m |
pace | | ≡ 2.5 ft | = 0.762 m |
palm | | ≡ 3 in | = 76.2 mm |
parsec | pc | ≈ 180 × 60 × 60/π AU = 206264.8062 AU = 3.26156378 light-years | = 3.08567782 ×1016 ± 6×106 m [2] |
point (ATA) | pt | ≡ 0.013837 in | = 0.351 459 8 mm |
point (Didot; European) | pt | | ≡ 0.376 065 mm |
point (metric) | pt | ≡ 3/8 mm | = 0.375 mm |
point (PostScript) | pt | ≡ 1/72 in | ≈ 0.352 778 mm |
quarter | | ≡ ¼ yd | = 0.2286 m |
rod; pole; perch | rd | ≡ 16 ½ ft | = 5.0292 m |
rope | rope | ≡ 20 ft | = 6.096 m |
span | | ≡ 6 in | = 0.1524 m |
span (cloth) | | ≡ 9 in | = 0.2286 m |
spat[3] | | ≡ 1012 m | = 1 Tm |
stick | | ≡ 2 in | = 50.8 mm |
stigma; pm | | ≡ 1.000×10−12 m | ≡ 1.000×10−12 m |
telegraph mile | mi | ≡ 6087 ft | = 1855.3176 m |
twip | twp | ≡ 1/1440 in | ≈ 1.763 889×10−5 m |
x unit; siegbahn | xu | | ≈ 1.0021×10−13 m |
yard (International) | yd | ≡3 ft ≡ 0.9144 m [1] | = 0.9144 m |
[edit] Area
Area, A Name of unit | Symbol | Definition | Relation to SI units |
acre | ac | ≡ 10 sq ch = 4840 sq yd | = 4046.856 422 4 m² |
are | a | | ≡ 100 m² |
barn | b | | ≡ 10−28 m² |
barony | | ≡ 4000 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 in² | ≈ 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 | | ≡ 1000 m² | = 1000 m² |
hectare | ha | ≡ 10 000 m² | = 0.01 km² |
hide | | ≡ 100 ac | = 4.046 856 422 4×105 m² |
rood | ro | ≡ ¼ ac | = 1011.714 105 6 m² |
square chain | sq ch | ≡ 1 ch² | = 404.685 642 24 m² |
square foot | sq ft | ≡ 1 ft² | = 9.290 304×10−2 m² |
square inch | sq in | ≡ 1 in² | = 6.4516×10−4 m² |
square kilometre | km² | ≡ 1 km² | = 106 m² |
square link | sq lnk | ≡ 1 lnk² | = 4.046 856 422 4×10−2 m² |
square metre (SI unit) | m² | ≡ 1 m × 1 m | = 1 m² |
square mil; square thou | sq mil | ≡ 1 mil² | = 6.4516×10−10 m² |
square mile; section | sq mi | ≡ 1 mi² | = 2.589 988 110 336×106 m² |
square rod/pole/perch | sq rd | ≡ 1 rd² | = 25.292 852 64 m² |
square U.S. Survey foot | sq ft | ≡ 1 ft (US)² | ≈ 9.290 341 161 327 49×10-2 m² |
square U.S. Survey mile | sq mi | ≡ 1 mi (US)² | ≈ 2.589 998×106 m² |
square yard | sq yd | ≡ 1 yd² | = 0.836 127 36 m² |
stremma | | ≡ 1000 m² | = 1000 m² |
township | | ≡ 36 sq mi (US) | ≈ 9.323 994×107 m² |
yardland | | ≡ 30 ac | = 1.214 056 926 72×105 m² |
[edit] Volume
Volume, V Name of unit | Symbol | Definition | Relation to SI units |
cubic metre (SI unit) | m³ | ≡ 1 m × 1 m × 1 m | |
litre | L | | ≡ 1 dm³ |
lambda | λ | ≡ 1 mm³ | = 1 μL |
drop (metric) | | ≡ 1/20 mL | = 0.05 mL |
minim (Imperial) | min | ≡ 1/480 fl oz (Imp) = 1/60 fl dr (Imp) | ≈ 0.059 193 880 208 333 mL |
minim (U.S.) | min | ≡ 1/480 US fl oz = 1/60 US fl dr | = 0.061 611 519 921 875 mL |
drop (U.S.) (alt) | gtt | ≡ 1/456 US fl oz | ≈ 0.064 854 231 mL |
drop (Imperial) (alt) | gtt | ≡ 1/1824 gi (Imp) | ≈ 0.077 886 684 mL |
drop (U.S.) | gtt | ≡ 1/360 US fl oz | = 0.082 148 693 229 1(6) mL |
drop (medical) | | ≡ 1/12 mL | = 0.08(3) mL |
drop (Imperial) | gtt | ≡ 1/288 fl oz (Imp) | = 0.098 656 467 013 (8) mL |
dash (U.S.) | | ≡ 1/96 US fl oz = ½ US pinch | = 0.308 057 599 609 375 mL |
dash (Imperial) | | ≡ 1/384 gi (Imp) = ½ pinch (Imp) | = 0.369 961 751 302 08(3) mL |
pinch (U.S.) | | ≡ 1/48 US fl oz = ⅛ US tsp | = 0.616 115 199 218 75 mL |
pinch (Imperial) | | ≡ 1/192 gi (Imp) = ⅛ tsp (Imp) | = 0.739 923 502 604 1(6) mL |
fluid scruple (Imperial) | fl s | ≡ 1/24 fl oz (Imp) | = 1.183 877 604 1(6) mL |
fluid drachm (Imperial) | fl dr | ≡ ⅛ fl oz (Imp) | = 3.551 632 812 5 mL |
fluid dram (U.S.); U.S. fluidram | fl dr | ≡ ⅛ US fl oz | = 3.696 691 195 312 5 mL |
teaspoon (Canadian) | tsp | ≡ 1/6 fl oz (Imp) | ≈ 4.735 510 416 667 mL |
teaspoon (U.S.) | tsp | ≡ 1/6 US fl oz | = 4.928 921 595 mL |
teaspoon (metric) | | | ≡ 5 mL |
teaspoon (Imperial) | tsp | ≡ 1/24 gi (Imp) | = 5.919 388 020 8(3) mL |
dessertspoon (Imperial) | | ≡ 1/12 gi (Imp) | = 11.838 776 041 (6) mL |
tablespoon (Canadian) | tbsp | ≡ ½ fl oz (Imp) | = 14.206 531 25 mL |
tablespoon (U.S.) | tbsp | ≡ ½ US fl oz | = 14.786 764 782 5 mL |
tablespoon (metric) | | | ≡ 15 mL |
cubic inch | cu in | ≡ 1 in³ | = 16.387 064 mL |
tablespoon (Imperial) | tbsp | ≡ 5/8 fl oz (Imp) | = 17.758 164 062 5 mL |
pony | | ≡ 3/4 US fl oz | = 22.180 147 171 875 mL |
fluid ounce (Imperial) | fl oz (Imp) | ≡ 1/160 gal (Imp) | = 28.413 062 5 mL |
fluid ounce (U.S.) | fl oz (US) | ≡ 1/128 gal (US) | = 29.573 529 562 5 mL |
shot | | ≡ 1 US fl oz | = 29.573 529 562 5 mL |
jigger | | ≡ 1½ US fl oz | = 44.360 294 343 75 mL |
gill (U.S.) | gi (US) | ≡ 4 US fl oz | = 118.294 118 25 mL |
gill (Imperial); Noggin | gi (Imp); nog | ≡ 5 fl oz (Imp) | = 142.065 312 5 mL |
cup (Canadian) | c (CA) | ≡ 8 fl oz (Imp) | = 227.3045 mL |
cup (U.S.) | c (US) | ≡ 8 US fl oz ≡ 1/16 gal (US) | = 236.588 236 5 mL |
cup (metric) | c | | ≡ 250 mL |
breakfast cup | | ≡ 10 fl oz (Imp) | = 284.130 625 mL |
pint (U.S. fluid) | pt (US fl) | ≡ ⅛ gal (US) | = 473.176 473 mL |
pint (U.S. dry) | pt (US dry) | ≡ 1/64 bu (US lvl) ≡ ⅛ gal (US dry) | = 0.550 610 471 357 5 L |
pint (Imperial) | pt (Imp) | ≡ ⅛ gal (Imp) | = 0.568 261 25 L |
fifth | | ≡ 1/5 US gal | = 0.757 082 356 8 L |
quart (U.S. fluid) | qt (US) | ≡ ¼ gal (US fl) | = 0.946 352 946 L |
quart (U.S. dry) | qt (US) | ≡ 1/32 bu (US lvl) = ¼ gal (US dry) | = 1.101 220 942 715 L |
quart (Imperial) | qt (Imp) | ≡ ¼ gal (Imp) | = 1.136 522 5 L |
pottle; quartern | | ≡ ½ gal (Imp) = 80 fl oz (Imp) | = 2.273 045 L |
board-foot | fbm | ≡ 144 cu in | = 2.359 737 216 L |
gallon (U.S. fluid; Wine) | gal (US) | ≡ 231 cu in | = 3.785 411 784 L |
gallon (U.S. dry) | gal (US) | ≡ ⅛ bu (US lvl) | = 4.404 883 770 86 L |
gallon (Imperial) | gal (Imp) | ≡ | = 4.546 09 L |
beer gallon | beer gal | ≡ 282 cu in | = 4.621 152 048 L |
peck (U.S. dry) | pk | ≡ ¼ US lvl bu | = 8.809 767 541 72 L |
peck (Imperial) | pk | ≡ 2 gal (Imp) | = 9.092 18 L |
bucket (Imperial) | bkt | ≡ 4 gal (Imp) | = 18.184 36 L |
timber foot | | ≡ 1 cu ft | = 28.316 846 592 L |
cubic foot | cu ft | ≡ 1 ft × 1 ft × 1 ft | = 28.316 846 592 L |
firkin | | ≡ 9 gal (US) | = 34.068 706 056 L |
bushel (U.S. dry level) | bu (US lvl) | ≡ 2150.42 cu in | = 35.239 070 166 88 L |
bushel (Imperial) | bu (Imp) | ≡ 8 gal (Imp) | = 36.368 72 L |
bushel (U.S. dry heaped) | bu (US) | ≡ 1 ¼ bu (US lvl) | = 44.048 837 708 6 L |
strike (U.S.) | | ≡ 2 bu (US lvl) | = 70.478 140 333 76 L |
strike (Imperial) | | ≡ 2 bu (Imp) | = 72.737 44 L |
kilderkin | | ≡ 18 gal (Imp) | = 81.829 62 L |
sack (U.S.) | | ≡ 3 bu (US lvl) | = 105.717 210 500 64 L |
sack (Imperial); bag | | ≡ 3 bu (Imp) | = 109.106 16 L |
barrel (U.S. dry) | bl (US) | ≡ 105 qt (US) = 105/32 bu (US lvl) | = 115.628 198 985 075 L |
barrel (U.S. fluid) | fl bl (US) | ≡ 31½ gal (US) | = 119.240 471 196 L |
coomb | | ≡ 4 bu (Imp) | = 145.474 88 L |
barrel (petroleum) | bl | ≡ 42 gal (US) | = 158.987 294 928 L |
barrel (Imperial) | bl (Imp) | ≡ 36 gal (Imp) | = 163.659 24 L |
hogshead (U.S.) | hhd (US) | ≡ 2 fl bl (US) | = 238.480 942 392 L |
seam | | ≡ 8 bu (US lvl) | = 281.912 561 335 04 L |
quarter; pail | | ≡ 8 bu (Imp) | = 290.949 76 L |
hogshead (Imperial) | hhd (Imp) | ≡ 2 bl (Imp) | = 327.318 48 L |
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) | = 1.409 562 806 675 2 m³ |
load | | ≡ 50 cu ft | = 1.415 842 329 6 m³ |
register ton | | ≡ 100 cu ft | = 2.831 684 659 2 m³ |
last | | ≡ 80 bu (Imp) | = 2.909 497 6 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 |
acre-foot | | ≡ 1 ac × 1 ft | = 1233.481 837 547 52 m³ |
cubic mile | cu mi | ≡ 1 mi³ | = 4.168 181 825 440 579 584 km³ |
[edit] Angle
Angle Name of unit | Symbol | Definition | Relation to SI units |
radian (SI unit) | rad | | ≡ 1 rad |
centesimal second of arc | " | ≡ 1 gr/10000 | ≈ 1.570 796 µrad |
arcsecond | " | ≡ 1°/3600 | ≈ 4.848 137 µrad |
centesimal minute of arc | ' | ≡ 1 gr/100 | ≈ 0.157 080 mrad |
minute of arc | ' | ≡ 1°/60 | ≈ 0.290 888 mrad |
angular mil | µ | ≡ 2π/6400 rad | ≈ 0.981 748 mrad |
grad; gradian; gon | gr | ≡ 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, m Name of unit | Symbol | Definition | Relation to SI units | Relation to avoirdupois units |
kilogram, grave | kg; G | | (SI base unit) | |
electron rest mass | me | | ≈ 9.109 381 88×10−31 ± 72×10−39 kg | |
atomic unit of mass | au[citation needed] | ≡ me | ≈ 9.109 381 88×10−31 ± 72×10−39 kg | |
unified atomic mass unit | u | | ≈ 1.660 538 73×10−27 ± 13×10−35 kg | |
dalton | Da | | ≈ 1.660 902 10×10−27 ± 13×10−35 kg | |
gamma | γ | | ≡ 1 μg | |
point | | ≡ 1/100 kt (metric) | = 2 mg | |
mite | | ≡ 1/20 gr | = 3.239 945 5 mg | |
mite (metric) | | ≡ 1/20 g | = 50 mg | |
grain | gr | | ≡ 64.798 91 mg | |
crith | | | ≈ 89.9349 mg | |
carat (metric) | kt | | ≡ 200 mg | |
carat | kt | ≡ 3 1/6 gr | ≈ 205.196 548 333 mg | |
sheet | | ≡ 1/700 lb av | = 647.9891 mg | |
scruple (avoirdupois) | s av | ≡ 20 gr | = 1.295 978 2 g | |
pennyweight | dwt; pwt | ≡ 1/20 oz t | = 1.555 173 84 g | |
dram (avoirdupois) | dr av | ≡ 27 11/32 gr | = 1.771 845 195 312 5 g | |
dram (apothecary; troy) | dr t | ≡ 60 gr | = 3.887 934 6 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 | = 31.103 476 8 g | |
assay ton (long) | AT | ≡ 1 mg × 1 long tn ÷ 1 oz t | ≈ 32.666 667 g | |
mark | | ≡ 8 oz t | = 248.827 814 4 g | |
pound (troy) | lb t | ≡ 5760 grains | = 0.373 241 721 6 kg | |
pound (avoirdupois) | lb av | ≡ 7000 grains | = 0.453 592 37 kg | |
pound (metric) | | | ≡ 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 | |
wey | | ≡ 252 lb = 18 st | = 114.305 277 24 kg (variants exist) | |
long quarter | | ≡ ¼ long tn | = 254.011 727 2 kg | |
kip | kip | ≡ 1000 lb av | = 453.592 37 kg | |
short ton | sh tn | ≡ 2000 lb | = 907.184 74 kg | |
tonne (mts unit) | t | | ≡ 1000 kg | |
long ton | long tn or ton | ≡ 2240 lb | = 1016.046 908 8 kg | |
barge | | ≡ 22 ½ sh tn | = 20,411.656 65 kg | |
Zentner | Ztr. | | Definitions vary; see [3] and [4]. 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] Time
Time, t Name of unit | Symbol | Definition | Relation to SI units |
second | s | | (SI base unit) |
Planck time | | ≡ √(Gℏ/c5) | ≈ 1.351 211 818×10−43 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 | ≈ 16.666 667 ms |
jiffy (alternate) | | ≡ 1/100 s | = 10 ms |
helek | | ≡ 1/1080 h | ≈ 3.333333 s |
minute | min | | ≡ 60 s |
milliday | md | ≡ 86 400 s / 1000 | ≡ 86.4 s |
moment | | ≡ 90 s | ≡ 90 s |
ke(traditional) | | ≡ 1/100 d | ≡ 864 s |
quarter (of an hour) | ke | ≡ 1/96 d | ≡ 900 s |
hour | h | ≡ 60 min | = 3600 s |
day | d | ≡ 24 h | = 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 or y | ≡ 365 d | = 31 536 000 s |
year (Gregorian) | a or y | ≡ 365.2425 d | = 31 556 952 s |
year (Julian) | a or y | ≡ 365.25 d | = 31 557 600 s |
sidereal year | a or y | ≡ 365.256363 d | = 31 558 149.76 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 | = 2.398 377 6×109 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) | | ≡ 1000 a of 365 d | = 3.1536×1010 s |
millennium (Gregorian) | | ≡ 1000 a of 365.2425 d | = 3.155 695 2×1010 s |
millennium (Julian) | | ≡ 1000 a of 365.25 d | = 3.155 76×1010 s |
Sothic cycle | | ≡ 1461 a of 365 d | = 4.607 409 6×1010 s |
[edit] Speed
Speed, v Name of unit | Symbol | Definition | Relation to SI units |
metre per second (SI unit) | m/s | | ≡ 1 m/s |
foot per hour | fph | ≡ 1 ft/h | ≈ 8.466 667×10−5 m/s |
furlong per fortnight | | ≡ ½ fur/wk | ≈ 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 | ≈ 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 km/s |
speed of light in vacuum | c | ≡ 2.997 924 58×108 m/s | |
[edit] Acceleration
Acceleration, a Name of unit | Symbol | Definition | Relation to SI units |
metre per second squared (SI unit) | 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 |
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, F Name of unit | Symbol | Definition | Relation to SI units |
newton (SI unit) | N | ≡ kg·m/s² | |
atomic unit of force | au | ≡ me·α²·c²/a0 | ≈ 8.238 722 241×10−8 N |
dyne (cgs unit) | dyn | ≡ g·cm/s² | ljm = 10−5 N |
milligrave-force, gravet-force | mGf; gf | ≡ g × 1 g | = 9.806 65 mN |
poundal | pdl | ≡ 1 lb·ft/s² | = 0.138 254 954 376 N |
ounce-force | ozf | ≡ g × 1 oz | = 0.278 013 850 953 781 2 N |
pound-force | lbf | ≡ g × 1 lb | = 4.448 221 615 260 5 N |
kilogram-force; kilopond; grave-force | kgf; kp; Gf | ≡ g × 1 kg | = 9.806 65 N |
sthene (mts unit) | sn | ≡ 1 t·m/s² | = 1 kN |
kip; kip-force | kip; kipf; klbf | ≡ g × 1000 lb | = 4.448 221 615 260 5 kN |
ton-force | tnf | ≡ g × 1 sh tn | = 8.896 443 230 521 kN |
See also: Conversion between weight (force) and mass
[edit] Pressure or mechanical stress
Pressure, p (lower case) Name of unit | Symbol | Definition | Relation to SI units |
atmosphere (standard) | atm | | ≡ 101 325 Pa [5] |
atmosphere (technical) | atm | ≡ 1 kgf/cm² | = 98.0665 kPa [5] |
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 kPa [5] |
centimetre of water (4 °C) | cmH2O | ≈ 999.972 kg/m³ × 1 cm × g | ≈ 98.0638 Pa [5] |
foot of mercury (conventional) | ftHg | ≡ 13 595.1 kg/m³ × 1 ft × g | ≈ 40.636 66 kPa [5] |
foot of water (39.2 °F) | ftH2O | ≈ 999.972 kg/m³ × 1 ft × g | ≈ 2.988 98 kPa [5] |
inch of mercury (conventional) | inHg | ≡ 13 595.1 kg/m³ × 1 in × g | ≈ 3.386 389 kPa [5] |
inch of water (39.2 °F) | inH2O | ≈ 999.972 kg/m³ × 1 in × g | ≈ 249.082 Pa [5] |
kilogram-force per square millimetre | kgf/mm² | ≡ 1 kgf/mm² | = 9.806 65 MPa [5] |
kip per square inch | ksi | ≡ 1 kipf/sq in | ≈ 6.894757 MPa [5] |
millimetre of mercury | mmHg | ≡ 13 595.1 kg/m³ × 1 mm × g ≈ 1 torr | ≈ 133.322 4 Pa [5] |
millimetre of water (3.98 °C) | mmH2O | ≈ 999.972 kg/m³ × 1 mm × g | = 9.806 38 Pa (= 0.999972 kgf/m²) |
pascal (SI unit) | Pa | ≡ N/m² | = kg/(m·s²) [6] |
pièze (mts unit) | pz | ≡ 1000 kg/m·s² | = 1 kPa |
pound per square foot | psf | ≡ 1 lbf/ft² | ≈ 47.880 25 Pa [5] |
poundal per square foot | pdl/sq ft | ≡ 1 pdl/sq ft | ≈ 1.488 164 Pa [5] |
pound per square inch | psi | ≡ 1 lbf/in² | ≈ 6.894 757 kPa [5] |
short ton per square foot | | ≡ 1 sh tn × g / 1 sq ft | ≈ 95.760 518 kPa |
torr | torr | ≡ 101 325/760 Pa | ≈ 133.322 4 Pa [5] |
[edit] Energy, work, or heat
Energy, E Name of unit | Symbol | Definition | Relation to SI units |
joule (SI unit) | J | ≡ N·m = W·s = V·A·s | = kg·m²/s² |
electronvolt | eV | ≡ e × 1 V | ≈ 1.602 176×10−19 J |
rydberg | Ry | ≡ R∞·ℎ·c | ≈ 2.179 872×10−18 J |
hartree | Eh | ≡ me·α²·c² (= 2 Ry) | ≈ 4.359 744×10−18 J |
atomic unit of energy | au | ≡ Eh | ≈ 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 | = 0.112 984 829 027 616 7 J |
Foot-pound force | ft lbf | ≡ g × 1 lb × 1 ft | = 1.355 817 948 331 400 4 J |
calorie (20 °C) | cal20 °C | | ≈ 4.1819 J |
calorie (thermochemical) | calth | | ≡ 4.184 J |
calorie (15 °C) | cal15 °C | | ≡ 4.1855 J |
calorie (International Table) | calIT | | ≡ 4.1868 J |
calorie (mean) | calmean | | ≈ 4.190 02 J |
calorie (3.98 °C) | cal3.98 °C | | ≈ 4.2045 J |
litre-atmosphere | l atm; sl | ≡ 1 atm × 1 L | = 101.325 J |
gallon-atmosphere (U.S.) | US gal atm | ≡ 1 atm × 1 gal (US) | = 383.556 849 013 8 J |
gallon-atmosphere (Imperial) | US gal atm | ≡ 1 atm × 1 gal (Imp) | = 460.632 569 25 J |
British thermal unit (thermochemical) | BTUth | ≡ 1 lb/g × 1 calth × 1 °F/°C = 9.489 152 380 4 ÷ 9 kJ | ≈ 1.054 350 kJ |
British thermal unit (ISO) | BTUISO | | ≡ 1.0545 kJ |
British thermal unit (63 °F) | BTU63 °F | | ≈ 1.0546 kJ |
British thermal unit (60 °F) | BTU60 °F | | ≈ 1.054 68 kJ |
British thermal unit (59 °F) | BTU59 °F | | ≡ 1.054 804 kJ |
British thermal unit (International Table) | BTUIT | ≡ 1 lb/g × 1 calIT × 1 °F/°C | = 1.055 055 852 62 kJ |
British thermal unit (mean) | BTUmean | | ≈ 1.055 87 kJ |
British thermal unit (39 °F) | BTU39 °F | | ≈ 1.059 67 kJ |
Celsius heat unit (International Table) | CHUIT | ≡ 1 BTUIT × 1 °C/°F | = 1.899 100 534 716 kJ |
cubic foot of atmosphere; standard cubic foot | cu ft atm; scf | ≡ 1 atm × 1 ft³ | = 2.869 204 480 934 4 kJ |
kilocalorie; large calorie | kcal; Cal | ≡ 1000 calIT | = 4.1868 kJ |
cubic yard of atmosphere; standard cubic yard | cu yd atm; scy | ≡ 1 atm × 1 yd³ | = 77.468 520 985 228 8 kJ |
cubic foot of natural gas | | ≡ 1000 BTUIT | = 1.055 055 852 62 MJ |
horsepower-hour | hp·h | ≡ 1 hp × 1 h | = 2.6845 MJ |
kilowatt-hour; Board of Trade Unit | kW·h; B.O.T.U. | ≡ 1 kW × 1 h | = 3.6 MJ |
thermie | th | ≡ 1 McalIT | = 4.1868 MJ |
therm (U.S.) | | ≡ 100 000 BTU59 °F | = 105.4804 MJ |
therm (E.C.) | | ≡ 100 000 BTUIT | = 105.505 585 262 MJ |
ton of TNT | tTNT | ≡ 1 Gcalth | = 4.184 GJ |
barrel of oil equivalent | bboe | ≈ 5.8 MBTU59 °F | ≈ 6.12 GJ |
ton of coal equivalent | TCE | ≡ 7 Gcalth | = 29.3076 GJ |
ton of oil equivalent | TOE | ≡ 10 Gcalth | = 41.868 GJ |
quad | | ≡ 1015 BTUIT | = 1.055 055 852 62 EJ |
[edit] Power
Power, P Name of unit | Symbol | Definition | Relation to SI units |
watt (SI unit) | W | ≡ J/s = N·m/s | = kg·m²/s³ |
lusec | lusec | ≡ 1 L·µmHg/s [7] | ≈ 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 | = 1.355 817 948 331 400 4 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 |
ton of air conditioning | | ≡ 1 t × 1005 J/kg × 1 °F/K ÷ 10 min | = 844.2 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 | = 2.869 204 480 934 4×103 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, L, J Name of unit | Symbol | Definition | Relation to SI units |
SI unit | J·s | | ≡ kg·m²/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 |
[edit] Electric current
Electric current, I Name of unit | Symbol | Definition | Relation to SI units |
ampere | A | | (SI base unit) |
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 |
[edit] Electric charge
Electric charge, Q Name of unit | Symbol | Definition | Relation to SI units |
coulomb (SI unit) | C | | ≡ A·s |
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 |
faraday | F | ≡ 1 mol × NA·e | ≈ 96,485.3383 C |
[edit] Electromotive force
Voltage, Electromotive force, U Name of unit | Symbol | Definition | Relation to SI units |
volt (SI unit) | V | | ≡ kg·m²/(A·s³) |
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, R Name of unit | Symbol | Definition | Relation to SI units |
ohm (SI unit) | Ω | ≡ V/A | = kg·m²/(A²·s³) |
[edit] Dynamic viscosity
Dynamic viscosity, η Name of unit | Symbol | Definition | Relation to SI units |
pascal second (SI unit) | Pa·s | ≡ N·s/m² | = kg/(m·s) |
poise (cgs unit) | P | | ≡ 10−1 Pa·s |
[edit] Kinematic viscosity
Kinematic viscosity, ν Name of unit | Symbol | Definition | Relation to SI units |
SI unit | m²/s | | ≡ m²/s |
stokes (cgs unit) | St | | ≡ 10−4 m²/s |
[edit] Information entropy
Information entropy, H Name of unit | Symbol | Definition | Relation to SI units |
SI unit | J/K | | ≡ 1 J/K |
nat; nip; nepit | nat | ≡ kB | = 1.3806505(23) × 10−23 J/K |
bit; shannon | bit; b; Sh | ≡ ln(2) × kB | = 9.569940(16) × 10−24 J/K |
ban; hartley | ban; Hart | ≡ ln(10) × kB | = 3.1790653(53) × 10−23 J/K |
nibble | | ≡ 4 bits | = 3.8279760(64) × 10−23 J/K |
byte | B | ≡ 8 bits | = 7.655952(13) × 10−23 J/K |
kilobyte (kibibyte) | KB; KiB | ≡ 1024 B | = 7.839695(13) × 10−23 J/K |
[edit] Temperature
Temperature, T Name of unit | Symbol | Relation to SI units | Relation to °C |
kelvin | K | SI base unit | T[K] = T[°C] + 273.15 |
degree Celsius | °C | T[°C] = T[K] − 273.15 | |
degree Rankine | °R; °Ra | T[°Ra] = 1.8 × T[K] | |
degree Fahrenheit | °F | T[°F] = T[K] × 1.8 − 459.67 | T[°F] = 1.8 × T[°C] + 32 |
[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 (Unix program) — a popular command-line utility.
- UDUNITS — a similar utility and programming library
- Convert — free downloadable executable for Windows
- Google — many conversions can be performed by typing the source and target units directly in the Google search box, using the keyword in, as explained in Google Calculator Help. For example:
-
120 m/s in mph
or 200 lb in stone
[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.