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 angstrm () = 10-10 m

1 nanometer = 10

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) = 1.056688103 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) = 3.1536107 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) = 9.47817210-4 British thermal unit (Btu)

1 cal (thermochemical) = 4.184 J = 3.96566710-3 Btu

1 Btu = 1055.056 J = 252.1644 cal = 2.93071110-4 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 = 0.947810-3 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)= 9.806650104 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 = 6.0231023 photons (Avogadro number)

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

1 electronvolt (eV) = 1.6021773310-19 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

Plancks constant, h = 6.61027 erg s

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

API gravity (0API)= 141.5/ sgro 131.5

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= 3.15361019 J/yr = 5.17109 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 = 1.41010 kcal =  1.63107 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 m)

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 m)

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