| Name of unit | Symbol | Relation to SI units |
|---|---|---|
| metre (SI base unit) | m | |
| bohr? (au) | a0, b | ~ 5.291 77 x 10-11 m |
| ångström | Å | = 10-10 m |
| micron | μ | = μm = 10-6 m |
| x unit | X | ~ 1.002 x 10-13 m |
| inch | in | = 2.54 x 10-2 m |
| foot | ft | = 12 in = 0.3048 m |
| yard | yd | = 3 ft = 0.9144 m |
| mile | mi | = 1760 yd = 1609.344 m |
| nautical mile | = 1852 m = 6076.1 feet | |
| geographical mile | = 1855 m = 6087.15 feet | |
| astronomical unit | AU | = 1.496 00 x 1011 m |
| parsec | pc | ~ 3.085 68 x 1016 m |
| light year | l.y. | ~ 9.460 528 x 1015 m |
| [light second]? | 299 792 458 m | |
| square metre (SI unit) | m2 | |
| barn? | b | 10-28 m2 |
| acre | ~ 4046.856 m2 | |
| are? | a | = 100 m2 |
| hectare? | ha | = 104 m2 |
| cubic metre (SI unit) | m3 | |
| litre | l, L | = dm3 = 10-3 m3 |
| lambda | λ | = μl = 10-6 dm3 |
| barrel (US) | ~ 158.987 dm3 | |
| gallon (US) | gal (US) | = 3.78541 dm3 |
| gallon (UK) | gal (UK) | = 4.546 09 dm3 |
| kilogram (SI base unit) | kg | |
| electron mass (au) | me | ~ 9.109 39 x 10-31 kg |
| unified atomic mass unit, dalton | u, Da | ~ 1.660 540 x 10-27 kg |
| gamma | γ | = μg |
| tonne | t | = 103 kg |
| pound (avoirdupois) | lb | = 0.453 592 37 kg |
| ounce (avoirdupois) | oz | ~ 28.3495 g |
| ounce (troy) | oz (troy) | ~ 31.1035g |
| grain | gr | = 64.798 91 mg |
| second (SI base unit) | s | |
| au of time | ~ 2.418 88 x 10-17 s | |
| minute | min | = 60 s |
| hour | h | = 3600 s |
| day | d | = 86 400 s (not exactly defined due to 'leap' seconds |
| year | a | ~ 31 556 952 s |
| svedberg | Sv | = ~ 10-13 s |
| (SI unit) | m.s-2 | |
| standard acceleration of free fall | gn | = 9.806 65 m.s-2 |
| galileo | Gal | = 10-2 m.s-2 |
| newton (SI unit) | N | = kg.m.s-2 |
| dyne ([cgs unit]?) | dyn | = 10-5N |
| au of force | ~ 8.238 73 x 10-8N | |
| pound-force | lbf | = 4.448 22 N |
| kilogram-force | kgf | = 9.806 65 N |
| joule (SI unit) | J = N.m | = kg.m2.s-2 |
| erg ([cgs unit]?) | erg | = 10-7 J |
| hartee (au) | Eh | ~4.359 75 x 10-18 J |
| rydberg | Ry | ~ 2.179 87 x 10-18 J |
| electronvolt | eV | = e x V ~ 1.602 18 x 10-19 J |
| calorie, thermochemical | calth | = 4.184 J |
| calorie, international | calIT | = 4.1868 J |
| 15 oC calorie | calIT | ~ 4.1855 J |
| litre atmosphere | l atm | = 101.325 J |
| British thermal unit | Btu | = 1055.06 J |
| pascal (SI unit) | Pa | = N.m-2 = kg.m-1.s-2 |
| atmosphere | atm | = 101 325 Pa |
| bar | bar | = 105 Pa |
| torr | Torr | = (101 325/760) Pa ~ 133.322 Pa |
| millimetre of mercury (conventional) | mmHg | = 13.5951 x 980.655 x 10-2 Pa ~ 133.322 Pa |
| pounds per square inch | psi | ~ 6.894 757 x 103 Pa |
| watt (SI unit) | W | = J.s-1 = N.m.s-1 = kg.m2.s-3 |
| horse power | hp | =745.7 W |
| SI unit | J.s. = N.m.s | = kg.m2.s-1 |
| cgs unit | erg.s | = 10-7 J.s |
| au of action | = h/2π = 1.054 57 x 10-34 J.s | |
| SI unit | Pa.s = N.m-2.s | = kg.m-1.s-1 |
| poise | P | = 10-1Pa.s |
| centipoise | cP | = mPa.s |
| SI unit | m2.s-1 | |
| stokes | St | = 10-4m2.s-1 |
| kelvin (SI base unit) | K | |
| degree Celsius | oC | T in oC = T in K - 273.15 |
| degree Fahrenheit | oF | T in oF = 1.8 (T in oC) + 32 |
| degree Rankine | oR | = (5/9) K |
A useful online converter is at
http://www.sciencemadesimple.com/conversions.html
The Unix program units? is a useful tool for units conversion.
![[Home]](wikipedia.png)