# Function: unitMass()

[**lifecycle-kit**](https://jonbogaty.com/lifecycle-kit/api/readme/index.md)

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[lifecycle-kit](https://jonbogaty.com/lifecycle-kit/api/readme/index.md) / [chem](https://jonbogaty.com/lifecycle-kit/api/chem/readme/index.md) / unitMass


# Function: unitMass() {#function-unitmass}


> **unitMass**(`id`, `backbone?`): `number`

Defined in: [chem/biomolecules.ts:144](https://github.com/jbcom/lifecycle-kit/blob/074e4e7b8038d3e2de9eb44c4b5b5aee0ef02b48/src/chem/biomolecules.ts#L144)

Mass of one unit of a biomolecule, in u.


## Parameters {#parameters}



### id {#id}


`string`


### backbone? {#backbone}


[`Backbone`](https://jonbogaty.com/lifecycle-kit/api/chem/type-aliases/backbone/index.md) = `"C"`


## Returns {#returns}


`number`