Useful Units and Conversions

Online unit conversion

Prefixes for units in the International System

 Prefix Symbol Power Example USA/Other exa E 1018 quintillion peta P 1015 petagram (Pg) quadrillion/billiard tera T 1012 terawatt (TW) trillion/billion giga G 109 gigawatt (GW) billion/milliard mega M 106 megawatt (MW) million kilo k 103 kilogram (kg) hecto h 102 hectoliter (hl) deka da 101 dekagram (dag) deci d 10-1 decimeter (dm) centi c 10-2 centimeter (cm) milli m 10-3 millimeter (mm) micro m 10-6 micrometer (m m) nano n 10-9 nanosecond (ns) pico p 10-12 picofarad (pf) femto f 10-15 femtogram (fg) atto a 10-18

Length:

1 meter = 100 cm = 1,000 mm = 3.281 ft = 39.37 inches (in)

1 foot = 12 inches (in) = 30.48 cm = 1/3 yard (yd)

1mile = 5,280 ft = 1.609 km

1 micron (mm)= 10-6 m

1 angström (Å) = 10-10 m

1 nanometer = 10 Å

Area:

1 m2 = 10-2 are (a) = 10-4 hectare (hecto-are, ha) = 10.76391 ft2

1 acre = 43,560 ft2 = 4,046.86 m2 = 0.4047 ha

1 ha = 2.4711 acre=104 m2=10-2 km2

Volume:

1 m3 = 106 cm3 = 103 liters (l) = 1.056688×103 quart (qt) = 264.1721 gal (U.S.)

1 liter (l) = 1.056688 quart (qt) = 0.2641721 gal (U.S.)

1 gallon (U.S.) = 4 qt = 3.785412 l = 0.1336806 ft3

1 barrel (bbl) = 42 gal (U.S.) = 159 l

Volume Abbreviations Used in Cookbooks

Abbreviation Unit of Measurement
tsp. (or t) teaspoon
tbs. (or T) tablespoon
C. (or c.) cup
oz. ounce
pt. pint
qt. quart
lb. pound

Liquid Measurement
Spoons and Cups Liquid Ounces
1 tsp. 1/6 oz.
1 tbs. 1/2 oz.
6 2/3 tbs. 3 1/2 oz.
1 C. (16 tbs.) 8 oz.
2 C. (1pt.) 16 oz. (1 lb.)
4 C. (1 qt.) 32 oz. (2 lbs.)
4 1/3 C. 2.2 lbs.

Volume Conversion for Ingredients
US System Metric System
Liquid 1 liquid qt. 0.95 liter
1.06 liquid qts. 1 liter
Dry 0.91 dry qts. 1 liter
1 dry qt. 1.1 liter

Time:

1 year (yr) = 3.1536×107 seconds (s)

1 day (d) = 86,400 s

Mass:

1 kg = 2.2046 pounds (lbs) = 10-3 metric ton (tonne) = 1000 grams

1 lb = 0.4535924 kg

1 metric ton = 0.9842 long ton = 1.102311 short ton

1 short ton = 2,000 lbs = 0.9071847 metric ton

1 long ton = 2,240 lbs = 1.016047 metric ton

Energy:

1 joule (J) = 0.2390057 calorie (cal) = 9.478172×10-4 British thermal unit (Btu)

1 cal (thermochemical) = 4.184 J = 3.965667×10-3 Btu

1 Btu = 1055.056 J = 252.1644 cal = 2.930711×10-4 kilowatt-hour (kWh)

1 kWh = 3.6 megajoule (MJ) = 0.8604207 Mcal = 3412.142 Btu

1 quad = 1015 Btu

##### Energy quantities expressed in Joules
 international BTU 1956 = 1055.056 electron volt (eV) = 1.6021892*10-19 medium BTU = 1055.87 erg = 1*10-7 BTU a 39 °F = 1059.67 frigoria (fr fg) = 4.1855*103 BTU a 60 °F = 1054.68 great calorie (Cal, kcal) = 4.1868*103 BTU thermochemical = 1054.35 joule international, 1948 = 1.000165 international calorie (cal) = 4.1868 termia (th) = 4.1855*106 medium calorie =  4.19002 therm = 1.055056*108 calorie, thermochemical = 4.184 tonne of dynamite (TNT) = 4.2*109 calorie at 15 °C = 4.1855 tonne equiv. petroleum (tep) = 4.1868*1010 calorie at 20 °C = 4.18190 watt-hour (Wh) = 3.6*103 horse-hour (CVh) = 2.64779*106 centigrade heat unit (CHU) = 1.8991

 BTU: British Termal Unit, equivalent to the quantity of heat necessary to raise the temperature of a pound of pure water from 60 to 61 °F, and it is 1054.5 Joule. BTUIT: Btu international, has been introduced so that the values expressed in kcal/kg and in Btu/lb °F coincide.

Power:

1 W = 1 J/s = 0.9478×10-3 Btu/s = 3.41214 Btu/hr = 1/745.7 HP

1 HP = 745.5 W = 0.706243 Btu/s = 178.1 cal/s

Pressure:

1 pascal (Pa) = 1 newton/m2 (N/m2)

1 physical atmosphere (atm) = 101325 Pa = 760 mm of mercury (mm Hg) = 14.69

lb-force/in2 (psi)

1 technical atmosphere (at) = 1 kilogram-force/cm2 (kG/cm2)= 9.806650×104 Pa

Energy content of monochromatic visible light

 Wavelength Color KJ/mole Kcal/mole Photon, eV 700 nm red 171 40.9 1.77 680 nm red(1) 174 41.5 1.81 600 nm yellow 199 47.7 2.07 500 nm blue 239 57.2 2.48 400 nm violet 299 71.5 3.10

(1) This is the wavelength of the red absorption maximum of chlorophyll

1 mole of photons = 6.023×1023 photons (Avogadro number)

Speed of light in vacuum = 299,792,458 m/s

1 electronvolt (eV) = 1.60217733×10-19 J

1 mole of eV = 96,499 J

Miscellaneous Useful Units and Conversions:

Universal gas constant, R = 8.314510 Pa m3 K-1 mol-1 = 82.5 atm cm3 K-1 mol-1 = 10.73 psi ft3 lb-mol-1 0R-1

Planck’s constant, h = 6.6×1027 erg s

Specific gravity of oil (sgro) = oil density/water density at 60oF

API gravity (0API)= 141.5/ sgro131.5

1 bbl oil = 136 kg for a 35 0API crude oil

Energy content of 1 bbl of crude oil = 6.1 GJ (@ 45 MJ/kg)

1 TW = 1TJ/s= 3.1536×1019 J/yr = 5.17×109 bbl oil/yr=5 Gbbl/yr

Energy content of 1 m3 of natural gas at standard conditions (14.7 psia and 600F) = 39 MJ

Specific energy contents:

Energy content of 1 metric ton of natural gas = 49 GJ

Energy content of 1 metric ton of crude oil = 45 GJ

Energy content of 1 metric ton of coal = 27 GJ (@ 27 MJ/kg)

#### Heats of combustion

 The principal characteristic of a fuel is its calorific value or heat of combustion. This represents the amount of heat developed in combustion at standard conditions. Generally, heat of combustion is measured in kcal/kg for solids and liquids, while for gases it is expressed in kcal/m3. In many fuels that contain hydrogen, we distinguish between a high calorific value (including the heat of condensation of water vapor evolved in the combustion) and a low calorific value (that does not consider the water vapor condensation).

#### Low calorific values of some fuels  (l.c.v.)

 fuel l.c.v. (kcal/kg - kcal/m3) firewood 2500 - 4500 peat 3000 - 4500 firewood coal 7500 lignite 4000 - 6200 lithantrax 6800 - 9000 anthracite 8000 - 8500 coke 7000 fuel oil 9800 fuel for airplane 10400 diesel oil 10200 gasoline for car 10500 crude oil 10000 liquified petroleum gas 11000 natural gas 8300 coke gas 4300 blast furnace gas 900

Solar energy fluxes:

Solar energy reaching 1 square meter of land in California  =  5 kWh/m2/day

Solar energy reaching 1ha in the temperate region in one year = 1.4×1010 kcal =  1.63×107 kWh = 58000 GJ/ha/year

Sieve Sizes

 Sieve Number Sieve Opening in mm Sieve Opening in inches 25.0 1.000 22.4 0.875 (7/8) 1 19.0 0.750 (3/4) 16.0 0.625 (5/8) 1.5 13.2 0.530 12.5 0.500 (1/2) 11.2 0.438 (7/16) 2 9.5 0.375 (3/8) 2.5 8.0 0.312 (5/16) 3.0 6.7 0.265 6.3 0.250 (1/4) 3.5 5.6 0.223 4 4.75 0.187 5 4.0 0.157 6 3.35 0.132 7 2.8 0.110 8 2.36 0.0937 10 2.0 0.0787 12 1.7 0.0661 14 1.4 0.0555 16 1.18 0.0469 18 1.0 0.0394 20 0.850 (850 µm) 0.0331 25 0.710 0.0278 30 0.600 0.0234 35 0.500 0.0197 40 0.425 0.0165 45 0.355 0.0139 50 0.300 0.0117 60 0.250 0.0098 70 0.212 0.0083 80 0.180 0.0070 100 0.150 0.0059 120 0.125 0.0049 140 0.106 0.0041 170 0.090 (90 µm) 0.0035 200 0.075 0.0029 230 0.063 0.0025 270 0.053 0.0021 325 0.045 0.0017 400 0.038 0.0015