# How many ppm is it?

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.

- Page: https://www.acalculator.org/chemistry/ppm-calculator
- JSON spec: https://www.acalculator.org/chemistry/ppm-calculator.json
- Version: f72f8bbde991

## Default answer

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).

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| from | I know | Whether you know the two masses, or a concentration to convert. |
| c | Concentration | The concentration you know, in the unit chosen next. |
| u | Unit | The unit of the concentration: ppm, ppb, parts per trillion, percent by mass, mg/kg or mg/L. |
| ms | Mass of solute | The mass of the dissolved substance. |
| mt | Mass of solution | The mass of the whole solution, solute included. |
| rho | Solution density | The density of the solution, for mg/L. Dilute water solutions are about 1 g/mL. |
| mm | Molar mass (g/mol) | Optional: the molar mass of the solute, to show the concentration in mol/L. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| ppm | Parts per million | Mass of solute ÷ mass of solution × 1,000,000. |
| ppb | Parts per billion | ppm × 1,000. |
| percent | Percent by mass | ppm ÷ 10,000. |
| mgL | Milligrams per liter | ppm × density in kg/L. |
| molL | Molarity | mg/L ÷ 1,000 ÷ molar mass: moles of solute per liter of solution. |

## 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.

## Assumptions

- 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

1. from = value, c = 15, u = ppb, rho = 1,000 gives ppm = 0.015, ppb = 15, mgL = 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.
2. from = masses, ms = 0.000004, mt = 0.005, rho = 1,000 gives percent = 0.075, ppm = 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.
3. from = value, c = 0.5, u = pct, rho = 1,000, mm = 58.44 gives ppm = 5,000, mgL = 5,000, molL = 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.
4. from = value, c = 250, u = mgL, rho = 1,250 gives ppm = 200, percent = 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.

## FAQ

### 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.

## Sources

- OpenStax, Chemistry 2e, §3.4 Other Units for Solution Concentrations: mass percentage; ppm = mass of solute ÷ mass of solution × 10⁶ ppm and ppb × 10⁹ ppb; Example 3.22 (3.75 mg of glucose in 5.0 g is 0.075%) and Example 3.25 (15 ppb of lead is 0.015 ppm). https://openstax.org/books/chemistry-2e/pages/3-4-other-units-for-solution-concentrations (retrieved 2026-10-02)