Units of Length
| meter (m) | = 39.37 inches (in.) = 1.094 yards (yd) |
| centimeter (cm) | = 0.01 m (exact, definition) |
| millimeter (mm) | = 0.001 m (exact, definition) |
| kilometer (km) | = 1000 m (exact, definition) |
| angstrom (Å) | = 10–8 cm (exact, definition) = 10–10 m (exact, definition) |
| yard (yd) | = 0.9144 m |
| inch (in.) | = 2.54 cm (exact, definition) |
| mile (US) | = 1.60934 km |
Table
C1
Units of Volume
| liter (L) | = 0.001 m3 (exact, definition) = 1000 cm3 (exact, definition) = 1.057 (US) quarts |
| milliliter (mL) | = 0.001 L (exact, definition) = 1 cm3 (exact, definition) |
| microliter | = 10–6 L (exact, definition) = 10–3 cm3 (exact, definition) |
| liquid quart (US) | = 32 (US) liquid ounces (exact, definition) = 0.25 (US) gallon (exact, definition) = 0.9463 L |
| dry quart | = 1.1012 L |
| cubic foot (US) | = 28.316 L |
Table
C2
Units of Mass
| gram (g) | = 0.001 kg (exact, definition) |
| milligram (mg) | = 0.001 g (exact, definition) |
| kilogram (kg) | = 1000 g (exact, definition) = 2.205 lb1 |
| ton (metric) | =1000 kg (exact, definition) = 2204.62 lb |
| ounce (oz) | = 28.35 g |
| pound (lb) | = 0.4535924 kg |
| ton (short) | =2000 lb (exact, definition) = 907.185 kg |
| ton (long) | = 2240 lb (exact, definition) = 1.016 metric ton |
Table
C3
Units of Energy
| 4.184 joule (J) | = 1 thermochemical calorie (cal) |
| 1 thermochemical calorie (cal) | = 4.184 107 erg |
| erg | = 10–7 J (exact, definition) |
| electron-volt (eV) | = 1.60218 10−19 J = 23.061 kcal mol−1 |
| liter∙atmosphere | = 24.217 cal = 101.325 J (exact, definition) |
| nutritional calorie (Cal) | = 1000 cal (exact, definition) = 4184 J |
| British thermal unit (BTU) | = 1054.804 J2 |
Table
C4
Units of Pressure
| torr | = 1 mm Hg (exact, definition) |
| pascal (Pa) | = N m–2 (exact, definition) = kg m–1 s–2 (exact, definition) |
| atmosphere (atm) | = 760 mm Hg (exact, definition) = 760 torr (exact, definition) = 101,325 N m–2 (exact, definition) = 101,325 Pa (exact, definition) |
| bar | = 105 Pa (exact, definition) = 105 kg m–1 s–2 (exact, definition) |
Table
C5
Footnotes
- 1Strictly speaking, the ounce and pound are units of weight, W (a force equal to the product of mass and gravitational acceleration, W = mg). The conversion relations in this table are commonly used to equate masses and weight assuming a nominal value for g at the surface of the earth.
- 2BTU is the amount of energy needed to heat one pound of water by one degree Fahrenheit. Therefore, the exact relationship of BTU to joules and other energy units depends on the temperature at which BTU is measured. 59 °F (15 °C) is the most widely used reference temperature for BTU definition in the United States. At this temperature, the conversion factor is the one provided in this table.