---
type: "fhirpath-function"
title: "FHIRPath Function: toQuantity"
function: "toQuantity"
category: "Conversion"
section: "5.5.7.1"
source: "fhirpath/functions.json"
---
# FHIRPath Function: toQuantity
_No canonical section match found in index.md._
## Summary
- **Category**: Conversion
- **Section**: `5.5.7.1`
- **Return Type**: `Quantity`
- **Empty Input Result**: `empty`
- **Errors on Multiple Input**: `true`
## Description
If the input collection contains a single item, this function will return a single quantity if the item is an Integer or Decimal, a Quantity, a String convertible to a Quantity, or a Boolean.
## Arguments
- `unit` (optional): `String` - Optional unit to convert to
## Type Mapping
- `Integer-Quantity`
- `Decimal-Quantity`
- `Quantity-Quantity`
- `String-Quantity`
- `Boolean-Quantity`
## Example
```fhirpath
q.toQuantity('g') // changes the value and units in the quantity according to UCUM conversion rules
```