---
type: "fhirpath-function"
title: "FHIRPath Function: toDateTime"
function: "toDateTime"
category: "Conversion"
section: "5.5.5.1"
source: "fhirpath/functions.json"
---
# FHIRPath Function: toDateTime
_No canonical section match found in index.md._
## Summary
- **Category**: Conversion
- **Section**: `5.5.5.1`
- **Return Type**: `DateTime`
- **Empty Input Result**: `empty`
- **Errors on Multiple Input**: `true`
## Description
If the input collection contains a single item, this function will return a single datetime if the item is a DateTime, a Date, or a String convertible to a DateTime.
## Arguments
- `format` (optional): `String` - Optional format template for parsing string input (STU). Uses date/datetime format codes when provided instead of the default format.
## Type Mapping
- `DateTime-DateTime`
- `Date-DateTime`
- `String-DateTime`
## Example
```fhirpath
'2022-01-01T12:00:00Z'.toDateTime() // returns @2022-01-01T12:00:00Z
```