Chemistry
PPM to Molarity Calculator
Convert a parts-per-million concentration into molarity for a solution of known density and solute molar mass.
Your inputs
Change any value to update the result instantly.
Molar concentration
0.0017 mol/L
Millimolar
1.7112 mmol/L
Micromolar
1,711.157 µmol/L
Mass concentration
100 mg/L
Density assumption
Dilute water-like solution: 1 ppm equals 1 mg/L
This mass-basis conversion applies to liquid solutions. Do not use it for ppm values defined by volume in air or by soil dry weight.
What this calculator does
Converts a mass-basis parts-per-million concentration into molarity using the solute molar mass and the solution density.
What your result means
The molar concentration of the solute in moles per litre of solution.
Formula and working
c = (ppm × ρ_solution) ÷ (1000 × M)
- 1
Collect the inputs
Concentration (mass basis) = 100 ppm (mg/kg); Molar mass of the solute (M) = 58.44 g/mol; Density of the solution (ρ) = 1 kg/L
- 2
Apply the formula
c = (ppm × ρ_solution) ÷ (1000 × M)
- 3
Result
Molar concentration = 0.0017 mol/L
Frequently asked questions
Symbols and assumptions
- ppm
- Milligrams of solute per kilogram of solution
- rho
- Solution density in kg/L
- M
- Molar mass in g/mol
- c
- Molarity in mol/L
- • ppm is defined on a mass basis (mg of solute per kg of solution).
- • For dilute water solutions the density is about 1 kg/L, so 1 ppm equals 1 mg/L.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • Do not apply this to ppm by volume in air or to ppm on a soil dry-weight basis; those use different definitions.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
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