• Concentrations
    Percentage (%) Part per Million (ppm) Part per Billion (ppb) Part per Trillion (ppt)
    1 10,000 10,000,000 10,000,000,000
    0.1 1,000 1,000,000 1,000,000,000
    0.0001 1 1,000 1,000,000
    0.0000001 0.001 1 1,000
    0.0000000001 0.000001 0.001 1
    0.0000000000001 0.000000001 0.000001 0.001
  • Common Units of Mass & Weight

    1 pound = 453.5924 grams
    1 pound = 453.5924 grams = 0.45359 kilograms = 7000 grains

    1 kilogram = 1000 grams = 2.205 pounds
    1 gram = 10 decigrams = 100 centigrams
    = 1000 milligrams

    1 metric ton = 1000 kilograms
    = 2204.62 pounds

  • Common Units of Length

    1 inch = 2.54 centimeters

    1 foot = 30.480 centimeters
    = 0.3048 meters
    1 mile = 5280 feet = 1.609 kilometers
    1 yard = 36 inches = 0.9144 meter

    1 meter = 100 centimeters = 39.37 inches
    = 3.281 feet
    = 1.094 yards

    1 kilometer = 1000 meter = 1094 yards
    = 0.6215 mile

    1 angstrom = 1.0 X 10-8 centimeter
    = 0.10 nanometer
    = 1.0 X 10-10 meter

  • Common Units of Volume

    1 liter = 1 cubic decimeter = 1000 cubic centimeters
    = 0.001 cubic meter

    1 milliliter = 1 cubic centimeter
    = 0.001 liter

    1 gallon = 3.7853 liters

  • Common Units of Pressure
    Unit N·m-2 (Pa) bar atm Torr (mm Hg) lbs/sq.in. (psi)
    1 N·m-2
    (1 Pa)
    1 10-5 9.8692X10-6 7.50062 X 10-3 1.45038 X 10-4
    1 bar 105 1 0.98692 750.062 14.5038
    1 atm 101325 1.01325 1 759.9988 14.6960
    1 Torr (1 mm Hg) 133.3224 1.333224 X 10-3 1.31579 X 10-3 1 1.93368 X 10-2
    10 lbs/sq.in. (psi) 68948 0.68948 0.68046 517.148 10
  • Common Units of Energy

    1 joule = 1 X 107 ergs

    1 calorie = 4.184 joules
    = 4.184 X 107 ergs
    = 4.129 X 10-2 liter-atmosphere
    = 2.612 X 10-19 electron volts

    1 erg = 1 X 10-7 joule = 2.3901 X 10-8 calorie

    1 electron volt = 1.6022 X 10-19 joule
    = 1.6022 X 10-12 erg
    = 96.487 kJ/mol

    1 liter atmosphere = 24.217 calories
    = 101.32 joules
    = 1.0132 X 109 ergs

    1 British Thermal Unit = 1055.06 joules
    = 1.05506 X 1010 ergs
    = 252.2 calories

  • Gas Constant

    R = 1.987 cal/mol K
    = 8.314 (N/m2) (m3)/ mol K
    = 0.08205 liter ·atm/ mole K

  • Common units of Temperature

    1 centigrade or Celsius degree = 1.8 Fahrenheit degree
    Temperature, Kelvin = T°C + 273.15
    Temperature, Fahrenheit = 9/5 °C +32
    Temperature, centigrade or Celsius = 5/9 (°F-32)

    To view complete detail of Common Units of Temperature Click here.

  • Transmittance to Absorbance Conversion

    A = 2.00-log %T
    Where, A = Absorbance of the solution
    %T = %Transmittance

    To view complete detail of Transmittance to Absorbance Click here.

  • Particle size Conversion
    Approximate Millimeter Mesh Size Approximate MicroneSize
    0.010 850 10
    0.020 635 20
    0.038 400 38
    0.045 325 45
    0.053 270 53
    0.063 230 63
    0.075 200 75
    0.090 170 90
    0.106 140 106
    0.125 120 125
    0.150 100 150
    0.180 80 180
    0.212 70 212
    0.250 60 250
    0.300 50 300
    0.355 45 355
    0.425 40 425
    0.500 35 500
    0.600 30 600
    0.710 25 710
    0.850 20 850
    1.000 18 1000
    1.180 16 1180
    1.400 14 1400
    1.700 12 1700
    2.000 10 2000
    2.360 8 2360
    2.800 7 2800
    3.350 6 3350
    4.000 5 4000
    4.750 4 4750
    0.425 40 425
    0.500 35 500
    0.600 30 600