# Summary

This article details the most common methods to quantify the concentration of a component in a mixture, and details how to convert between these concentrations. Concentration is commonly expressed in moles per volume, mass per volume, mass percentage, volume percentage, mole percentage and parts per million. Using density and/or molecular weight properties it is possible to convert between any of the above measures.

# Definitions

: | mass of component | |

: | Molecular weight | |

: | Parts per million | |

: | Parts per million, weight basis | |

: | Parts per million, volume basis | |

: | Parts per million, mole basis | |

: | Volume fraction | |

: | Mass fraction | |

: | Mol fraction | |

: | Density or mass per volume concentration |

# Concentration Conversions

Below are tabulated the concentration conversions between many measures of concentration. In all cases we are describing the concentration of substance 1 in total substance, and this is used in subscripts in the formulae below.

Click to jump to the section for converting from:

- Mol fraction
- Mass fraction
- Volume fraction
- Molar concentration (moles per volume)
- Mass per volume (sometimes called ppm)
- Parts per million (mol)
- Parts per million (weight)
- Parts per million (volume)

## Mol Fraction

Convert To | Typical Units | Convert From Mol/Mol (x) |
---|---|---|

mass/mass* | - | |

volume/volume* | - | |

molar concentration | mol/L | |

mass/vol | g/L | |

parts per million (ppm mol) |
μmol/mol | |

parts per million (ppm weight) |
mg/kg | |

parts per million (ppm volume) |
μL/L |

* multiply by 100 for mass, mole or volume %.

## Mass Fraction

Convert To | Typical Units | Convert From Mass/Mass (m) |
---|---|---|

mol/mol* | - | |

volume/volume* | - | |

molar fraction | mol/L | |

mass/vol | g/L | |

parts per million (ppm mol) |
μmol/mol | |

parts per million (ppm weight) |
mg/kg | |

parts per million (ppm volume) |
μL/L |

* multiply by 100 for mass, mole or volume %.

## Volume Fraction

Convert To | Typical Units | Convert From Vol/Vol (?) |
---|---|---|

mol/mol* | - | |

mass/mass* | - | |

molar fraction | mol/L | |

mass/vol | g/L | |

parts per million (ppm mol) |
μmol/mol | |

parts per million (ppm weight) |
mg/kg | |

parts per million (ppm volume) |
μL/L |

* multiply by 100 for mass, mole or volume %.

## Molar Concentration

Convert To | Typical Units | Convert From Molar Concentration (c) |
---|---|---|

mol/mol* | - | |

mass/mass* | - | |

volume/volume* | - | |

mass/vol | g/L | |

parts per million (ppm mol) |
μmol/mol | |

parts per million (ppm weight) |
mg/kg | |

parts per million (ppm volume) |
μL/L |

* multiply by 100 for mass, mole or volume %.

## Mass per Volume

Convert To | Typical Units | Convert From Mass/Volume (m_{1}/v_{tot}) |
---|---|---|

mol/mol* | - | |

mass/mass* | - | |

volume/volume* | - | |

molar fraction | mol/L | |

parts per million (ppm mol) |
μmol/mol | |

parts per million (ppm weight) |
mg/kg | |

parts per million (ppm volume) |
μL/L |

* multiply by 100 for mass, mole or volume %.

## Parts per million (ppm mol)

Convert To | Typical Units | Convert From ppm mol |
---|---|---|

mol/mol* | μmol/mol | |

mass/mass* | - | |

volume/volume* | - | |

molar fraction | mol/L | |

mass/vol | g/L | |

parts per million (ppm weight) |
mg/kg | |

parts per million (ppm volume) |
μL/L |

* multiply by 100 for mass, mole or volume %.

## Parts per million (ppm weight)

Convert To | Typical Units | Convert From ppm weight |
---|---|---|

mol/mol* | - | |

mass/mass* |
- | |

volume/volume* | - | |

molar fraction | mol/L | |

mass/vol | g/L | |

parts per million (ppm mol) |
μmol/mol | |

parts per million (ppm volume) |
μL/L |

* multiply by 100 for mass, mole or volume %.

## Parts per million (ppm volume)

Convert To | Typical Units | Convert From ppm volume |
---|---|---|

mol/mol* | - | |

mass/mass* | - | |

volume/volume* | - | |

molar fraction | mol/L | |

parts per million (ppm mol) |
μmol/mol | |

mass/vol | g/L | |

parts per million (ppm weight) |
mg/kg |

* multiply by 100 for mass, mole or volume %.