The units of ppm, ppb and ppt what are they mean?

When use for solution concentration, 1 ppm= 1 μg/mL, when use for solid component content, ppm=1 μg/g = 1 g/t. 1 ppb = part per thousand 1 ppm.

ppm part per million
ppb part per billion 10
ppt part per trillion

Conversions between this three units.

1 ppm= 1000 ppb
1 ppb= 1000 ppt
ppb :μg/L
ppt :ng/L


1, The concentration of the solution

Solution concentration have three categories:


Mass concentration(eg mass percent concentration): Solute concentration of the solution with the quality of the total mass of the solution expressed as a percentage called the mass percent concentration, represented by the symbol%.
Volume concentration(eg Molar concentration, Equivalent concentration).
Quality – volume concentration: The concentration per unit volume (1 m3 or 1 l) was included in the mass of the solute expressed in mass called – volume concentration, the symbol g / m3 or in mg / L.


2, ppm is  percentage of the weight: ppm= mg/kg= mg/L, eg, 1ppm=1ppm=1000ug/L , 1ppb=1ug/L=0.001mg


Gas concentration

1, Volume concentration: Volume concentration is used per cubic meter of air contained in the volume number (cubic centimeters) or contaminants (ml / m3) to represent. eg:

1 ppm=10 -6, 1 ppb=10 -9 , 1 ppt=10 -12,
1ppm=10 -3 ppb= 10 -6 ppt


2,Quality – volume concentration: The concentration of mass per cubic meter of air pollutants called to represent the mass – volume concentration unit is mg / m3 or g/m3.

the conversion with ppm:

C=22.4 X/M,

X: concentration of pollutants in the number of milligrams per cubic meter standard representation
C: pollutant concentration in ppm
M: per molecular weight contaminants

1 ppm=M/22.4(mg/m3)=1000.m/22.4 ug/m3


eg1, in the standard state, ppm concentration of 30 mg / standard cubic meters of hydrogen fluoride
The molecular weight of the hydrogen fluoride 20
C=30.22.4/20=33.6 ppm

eg1, concentration of ozone generator is 5 ppm,the concentration in mg / Nm3 expressed is?
The molecular weight weight of ozone is 48
X =5.64/22.4 mg/m3=14.3 mg/m3


3, Quality content conversion of ppm, ppb between soils, animals and plants, solid waste.

1 ppm=1 mg/kg=1000 μg/kg
1 ppb=1 μg/kg=10-3 mg/kg
1 mg/kg=1 ppm=1000 μg/kg
1 ug/kg=1 ppb=10-3 ppm