How many ppm is it?
Type a concentration to convert it, or the mass of a dissolved substance and of the whole solution. The calculator gives parts per million and the same amount in ppb, percent and mg/L.
- Parts per million
- 0.015
The concentration is 0.015 ppm (0.0000015% by mass, 0.015 mg/L).
- Parts per billionppb
- 15
- Percent by mass%
- 0.0000015
- Milligrams per litermg/L
- 0.015
Parts per million: 0.015. The concentration is 0.015 ppm (0.0000015% by mass, 0.015 mg/L).
How to calculate
Works out a concentration in parts per million (ppm) from the solute and solution masses, or converts ppm to and from ppb, percent, mg/kg and mg/L, and to mol/L with a molar mass.
Example with the default inputs (I know A concentration, Concentration 15, Unit ppb, Solution density 1 g/mL): The concentration is 0.015 ppm (0.0000015% by mass, 0.015 mg/L).
Method: ppm = mass of solute ÷ mass of solution × 10⁶; ppb = ppm × 1,000; % = ppm ÷ 10,000; mg/kg = ppm; mg/L = ppm × density (kg/L); mol/L = mg/L ÷ 1,000 ÷ molar mass.
- ppm, ppb and percent are by mass (mass of solute per mass of solution).
- mg/L needs the solution’s density; dilute water solutions are close to 1 g/mL, where 1 mg/L = 1 ppm.
- Arithmetic is exact on the typed decimals.
Worked examples
Each example is checked against the calculator on every build.
- I know A concentration, Concentration 15, Unit ppb, Solution density 1 g/mL gives Parts per million 0.015, Parts per billion 15, Milligrams per liter 0.015.Source: OpenStax, Chemistry 2e, §3.4 Other Units for Solution Concentrations (mass percentage; ppm = mass of solute ÷ mass of solution × 10⁶ ppm; ppb × 10⁹). https://openstax.org/books/chemistry-2e/pages/3-4-other-units-for-solution-concentrations, retrieved 2026-10-02, Example 3.25: 15 ppb is 0.015 ppm
- I know The masses, Mass of solute 0.00375 g, Mass of solution 5 g, Solution density 1 g/mL gives Percent by mass 0.075, Parts per million 750.Source: OpenStax, Chemistry 2e, §3.4 Other Units for Solution Concentrations (mass percentage; ppm = mass of solute ÷ mass of solution × 10⁶ ppm; ppb × 10⁹). https://openstax.org/books/chemistry-2e/pages/3-4-other-units-for-solution-concentrations, retrieved 2026-10-02, Example 3.22: 3.75 mg in 5.0 g is 0.075% by mass
- I know A concentration, Concentration 0.5, Unit % by mass, Solution density 1 g/mL, Molar mass (g/mol) 58.44 gives Parts per million 5,000, Milligrams per liter 5,000, Molarity 0.085558.Source: OpenStax, Chemistry 2e, §3.4 Other Units for Solution Concentrations (mass percentage; ppm = mass of solute ÷ mass of solution × 10⁶ ppm; ppb × 10⁹). https://openstax.org/books/chemistry-2e/pages/3-4-other-units-for-solution-concentrations, retrieved 2026-10-02
- I know A concentration, Concentration 250, Unit mg/L, Solution density 1.25 g/mL gives Parts per million 200, Percent by mass 0.02.Source: OpenStax, Chemistry 2e, §3.4 Other Units for Solution Concentrations (mass percentage; ppm = mass of solute ÷ mass of solution × 10⁶ ppm; ppb × 10⁹). https://openstax.org/books/chemistry-2e/pages/3-4-other-units-for-solution-concentrations, retrieved 2026-10-02
How it works
Parts per million compare the mass of a dissolved substance (the solute) with the mass of the whole solution:
ppm = mass of solute ÷ mass of solution × 10⁶
From a concentration you type, the page first finds ppm:
| Unit typed | ppm |
|---|---|
| ppm or mg/kg | the same number |
| ppb | ÷ 1,000 |
| ppt (parts per trillion) | ÷ 1,000,000 |
| % by mass | × 10,000 |
| mg/L | ÷ density in kg/L |
Then it shows ppb = ppm × 1,000, percent = ppm ÷ 10,000, mg/L = ppm × density in kg/L, and, with a molar mass M in g/mol, mol/L = mg/L ÷ 1,000 ÷ M.
Rules
- ppm, ppb and percent are by mass. The density (default 1 g/mL, close to dilute water solutions) is used only for mg/L and mol/L.
- A concentration over 1,000,000 ppm (100%) gives no answer, and so does a solute heavier than the solution. Two masses typed in different units that differ by less than one part in 10¹² count as equal (100%).
- Arithmetic is exact on the typed decimals; results show to 8 significant figures (mol/L to 6).
Worked examples by hand
15 ppb of lead. 15 ÷ 1,000 = 0.015 ppm; at 1 g/mL, 0.015 mg/L.
3.75 mg of glucose in 5.0 g. 0.00375 g ÷ 5.0 g = 0.00075. × 10⁶ = 750 ppm; × 100 = 0.075%.
0.5% salt water, 58.44 g/mol, 1 g/mL. 0.5 × 10,000 = 5,000 ppm = 5,000 mg/L = 5 g/L. 5 ÷ 58.44 = 0.0856 mol/L.
250 mg/L in a liquid of 1.25 g/mL. 250 ÷ 1.25 = 200 ppm = 0.02%.
Other questions people ask
How do I calculate ppm?
Divide the mass of the dissolved substance by the mass of the whole solution and multiply by 1,000,000. 3.75 mg of glucose in 5.0 g of fluid is 0.00375 ÷ 5.0 × 10⁶ = 750 ppm, which is 0.075% by mass.
How do I convert ppb to ppm?
Divide by 1,000. Lead at 15 ppb in drinking water is 15 ÷ 1,000 = 0.015 ppm.
How do I convert ppm to percent?
Divide by 10,000, because 1% is 10,000 ppm. 5,000 ppm is 0.5%, and 750 ppm is 0.075%.
Is 1 ppm the same as 1 mg/L?
For water and dilute water solutions, nearly: a liter weighs about 1 kg, and 1 mg/kg is 1 ppm. For a denser or lighter liquid, mg/L = ppm × density in kg/L, so type the density.
How do I convert ppm to molarity?
Turn ppm into mg/L with the density, divide by 1,000 to get g/L, then divide by the molar mass. 5,000 ppm of sodium chloride (58.44 g/mol) in a 1 g/mL solution is 5 g/L ÷ 58.44 = 0.0856 mol/L.
Is ppm by mass or by volume?
In chemistry ppm of a solution is usually by mass, as here. Gases are often given in ppm by volume (ppmv), which this calculator does not convert.