## Tables of conversion factors

### Legend

 Legend ≡ definition = exactly equal to ≈ approximately equal to (digits) indicates the digits repeat infinitely

### Length

 Length, l Name of unit Symbol Definition Relation to SI units angstrom Å ≡ 1.000×10−10 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 ≡ 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 ft = 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 ≡ 1.000×10−15 m = 1.000×10−15 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 = 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 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 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; nm ≡ 1852 m nautical mile (Admiralty) NM (Adm); nm (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 ≈ 206 264.806 25 AU = 3.261 563 776 9 ± 6 ×10−10 light-years = 3.085 677 581 3×1016 ± 6×106 m 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[citation needed] S ≡ 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 xu ≈ 1.0021×10−13 m yard (International) yd ≡3 ft ≡ 0.9144 m [1] = 0.9144 m

### 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 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

### 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

### Solid angle

 Solid angle Name of unit Symbol Definition Relation to SI units steradian sr

### Mass

 Mass, m Name of unit Symbol Definition Relation to SI units Relation to avoirdupois units kg; G electron rest mass me ≈ 9.109 381 88×10−31 ± 72×10−39 kg atomic unit of mass au ≡ me ≈ 9.109 381 88×10−31 ± 72×10−39 kg unified atomic mass unit amu ≈ 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 [2] and [3]. 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".

### Time

 Time, t Name of unit Symbol Definition Relation to SI units second s 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 moment ≡ 90 s ≡ 90 s ke(traditional) ≡ 1/100 d ≡ 864 s quarter (of an h) 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 ≡ 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

### 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 ≡ 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

### 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

### 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 dyn ≡ g·cm/s² ljm = 10−5 N milligrave-force, gravet 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

### Pressure or mechanical stress

 Pressure, p (lower case) Name of unit Symbol Definition Relation to SI units pascal (SI unit) Pa ≡ N/m² = kg/(m·s²) barye (cgs unit) ≡ 1 dyn/cm² = 0.1 Pa poundal per square foot pdl/sq ft ≡ 1 pdl/sq ft ≈ 1.488 164 Pa millimetre of water (3.98 °C) mmH2O ≈ 999.972 kg/m³ × 1 mm × g = 9.806 38 Pa (= 0.999972 kgf/m²) pound per square foot psf ≡ 1 lb/sq ft × g ≈ 47.880 259 Pa centimetre of water (3.98 °C) cmH2O ≈ 999.972 kg/m³ × 1 cm × g = 98.0638 Pa torr torr ≡ 101 325/760 Pa ≈ 133.322 368 4 Pa millimetre of mercury mmHg ≡ 13 595.1 kg/m³ × 1 mm × g ≈ 1 torr = 133.322 387 415 Pa inch of water (3.98 °C) inH2O ≈ 999.972 kg/m³ × 1 in × g = 249.082 Pa pièze (mts unit) pz ≡ 1000 kg/m·s² = 1 kPa centimetre of mercury cmHg ≡ 13 595.1 kg/m³ × 1 cm × g = 1.333 223 874 15 kPa foot of water (3.98 °C) ftH2O ≈ 999.972 kg/m³ × 1 ft × g = 2.988 98 kPa inch of mercury inHg ≡ 13 595.1 kg/m³ × 1 in × g = 3.386 388 640 341 kPa pound per square inch psi ≡ 1 lb × g / 1 sq in ≈ 6.894 757 kPa foot of mercury ftHg ≡ 13 595.1 kg/m³ × 1 ft × g = 40.636 663 684 091 9 kPa short ton per square foot ≡ 1 sh tn × g / 1 sq ft ≈ 95.760 518 kPa atmosphere (technical) atm ≡ 1 kgf/cm² = 98.0665 kPa bar bar ≡ 105 Pa atmosphere (standard) atm ≡ 101 325 Pa kip per square inch ksi ≡ 1 kipf/sq in ≈ 6.894757 MPa kilogram-force per square millimetre kgf/mm² ≡ 1 kgf/mm² = 9.806 65 MPa

### 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

### 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 [4] ≈ 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

### 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

### 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

### 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

### 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

### Electrical resistance

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

### 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

### 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

### 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

### 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