---
title: UnitConcentrationMass
framework: foundation
role: symbol
role_heading: Class
path: foundation/unitconcentrationmass
---

# UnitConcentrationMass

A unit of measure for concentration of mass.

## Declaration

```swift
class UnitConcentrationMass
```

## Overview

Overview You typically use instances of UnitConcentrationMass to represent specific quantities of concentration using the NSMeasurement class. Concentration of Mass Concentration is the abundance of a constituent within a volume. Concentration can be expressed by SI derived units in terms of kilograms per cubic meter (kg/m3). The UnitConcentrationMass class defines its baseUnit() as gramsPerLiter, and provides the following units, which are initialized using UnitConverterLinear converters with the specified coefficients:  |  |  |   |  |  |   |  |  |   |  |  |

## Topics

### Accessing the Base Unit

- [baseUnit()](foundation/dimension/baseunit().md)

### Accessing Predefined Units

- [gramsPerLiter](foundation/unitconcentrationmass/gramsperliter.md)
- [milligramsPerDeciliter](foundation/unitconcentrationmass/milligramsperdeciliter.md)
- [millimolesPerLiter(withGramsPerMole:)](foundation/unitconcentrationmass/millimolesperliter(withgramspermole:).md)

## Relationships

### Inherits From

- [Dimension](foundation/dimension.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSCoding](foundation/nscoding.md)
- [NSCopying](foundation/nscopying.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)
- [NSSecureCoding](foundation/nssecurecoding.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)

## See Also

### Concentration and Dispersion

- [UnitDispersion](foundation/unitdispersion.md)