---
type: "fhirpath-function"
title: "FHIRPath Function: abs"
function: "abs"
category: "Math"
section: "5.8.1"
source: "fhirpath/functions.json"
---
# FHIRPath Function: abs
{:.stu}

Returns the absolute value of the input (in the same type). When taking the absolute value of a quantity, the unit is unchanged.
{:.stu}

Accepts input types of Integer, Long, Decimal or Quantity.
{:.stu}

If the input collection is empty, the result is empty.
{:.stu}

If the input collection contains multiple items, the evaluation of the expression will end and signal an error to the calling environment.
{:.stu}

``` fhirpath
(-5).abs() // 5
(-5.5).abs() // 5.5
(-5.5 'mg').abs() // 5.5 'mg'
```
{:.stu}
## Summary
- **Category**: Math
- **Section**: `5.8.1`
- **Return Type**: `Integer | Long | Decimal | Quantity`
- **Empty Input Result**: `empty`
- **Errors on Multiple Input**: `true`
## Description
Returns the absolute value of the input. When taking the absolute value of a quantity, the unit is unchanged.
## Arguments
- none
## Type Mapping
- `Integer-Integer`
- `Long-Long`
- `Decimal-Decimal`
- `Quantity-Quantity`
## Example
```fhirpath
(-5).abs() // 5
(-5.5).abs() // 5.5
(-5.5 'mg').abs() // 5.5 'mg'
```