> For the complete documentation index, see [llms.txt](https://docs.cascade.io/cascade/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cascade.io/cascade/functions-and-expressions/functions/date-time/datetrunc.md).

# DATETRUNC

DATETRUNC(`date`, `date part`)

Truncate a date, or a series of dates, to the `date part` specified on input.

### Arguments

| Argument    | Description                                   |
| ----------- | --------------------------------------------- |
| `date`      | Date/time value(s)                            |
| `date part` | Part of the date/time value(s) to truncate by |

### Output

Date(s) corresponding to the start of the period specified by `date part`

### Example

{% embed url="<https://datawrapper.dwcdn.net/6oh8h/1>" %}