ppm / ppb Converter

mass concentration = mass fraction × density

Convert between mass fractions (ppm, ppb, mg/kg) and mass concentrations (mg/L, µg/mL) using a density you enter explicitly.

Conversion

Value

Input quantity type

Output quantity type

Convert to unit

Density of the solution / matrix

Required: mass fraction and mass concentration are different quantities.

Mass fraction cannot be converted to mass concentration without density. ppm (mg/kg) is only equal to mg/L when the solution density is exactly 1.000 g/mL.

Enter a value to convert.

About this calculator

“ppm” is ambiguous in the laboratory. As a mass fraction it means one milligram of analyte per kilogram of sample (mg/kg). As a mass concentration it is usually taken to mean one milligram per litre (mg/L). These are the same number only when the density of the matrix is exactly 1 g/mL.

This converter keeps the two quantities separate. Converting between them requires the density of the solution or matrix, which you must enter — LabCalc never assumes water, and never silently treats mg/kg as mg/L.

LabCalc is provided as a calculation aid. Users remain responsible for verifying calculations, units, chemical compatibility, experimental procedures and applicable safety requirements before laboratory use.

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