Calculate molarity in mol/L from a concentration in ppb using molar mass, with solution density, gas ppbv, and an EPA limit comparison.

Liquid uses solution density. Gas uses the ideal gas law at your temperature and pressure.

Picking a substance fills in the molar mass and compares your result with its US EPA reference limit.

Molar mass of the dissolved substance, for example 207.2 for lead or 62.00 for the nitrate ion.

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Ppb to Mol/L Formula

The following formula is used to calculate the molarity (mol/L) from the concentration in ppb and the molar mass.

M = (C × 10⁻⁹) / Mₘ

Variables:

  • M is the molarity (mol/L)
  • C is the concentration in ppb
  • M_m is the molar mass (g/mol)

To calculate the molarity, multiply the concentration in ppb by 10-9 and then divide by the molar mass.

ppb to mol/L Conversion Table (Requires molar mass; assumes 1 ppb = 1 µg/L)
Concentration (ppb) Molar Mass (g/mol) Molarity (mol/L)
1200.000000050
1500.000000020
11000.000000010
12000.000000005
5200.000000250
5500.000000100
51000.000000050
52000.000000025
10200.000000500
10500.000000200
101000.000000100
102000.000000050
50200.000002500
50500.000001000
501000.000000500
502000.000000250
100200.000005000
100500.000002000
1001000.000001000
1002000.000000500
* Rounded to 9 decimals. Formula: M (mol/L) = (ppb × 10⁻⁶ g/L) ÷ (molar mass in g/mol). Assumes water-like density (1 ppb ≈ 1 µg/L).

What is Ppb to Mol/L Conversion?

Ppb (parts per billion) to mol/L (molarity) conversion is a method used to express the concentration of a solution. Ppb is a unit of measurement that describes the amount of a substance in a billion parts of the solution. Molarity, on the other hand, is a measure of the concentration of a solute in a solution, expressed as the number of moles of solute per liter of solution. This conversion is essential in chemistry for preparing solutions with precise concentrations.

How to Calculate Ppb to Mol/L?

The following steps outline how to calculate the conversion from Ppb to Mol/L.


  1. First, determine the concentration in ppb (C).
  2. Next, determine the molar mass of the substance (M_m).
  3. Next, calculate the molarity using the formula M = (C * 10-9) / M_m.
  4. Finally, calculate the molarity.
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Concentration in ppb (C) = 500

Molar Mass (M_m) = 18 g/mol