> ## Documentation Index
> Fetch the complete documentation index at: https://axiom.co/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# unixtime_milliseconds_todatetime

> This page explains how to use the unixtime_milliseconds_todatetime function in APL.

`unixtime_milliseconds_todatetime` converts a Unix timestamp that’s expressed in whole milliseconds since 1970-01-01 00:00:00 UTC to an APL `datetime` value.

Use the function whenever you ingest data that stores time as epoch milliseconds (for example, JSON logs from NGINX or metrics that follow the StatsD line protocol). Converting to `datetime` lets you bin, filter, and visualize events with the rest of your time-series data.

## For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

<AccordionGroup>
  <Accordion title="Splunk SPL users">
    `unixtime_milliseconds_todatetime()` corresponds to an `eval` expression that divides the epoch value by 1000 and formats the result. You skip both steps in APL because the function takes milliseconds directly.

    <CodeGroup>
      ```sql Splunk example theme={null}
      | eval timestamp=strftime(epoch_ms/1000,"%Y-%m-%dT%H:%M:%SZ")
      ```

      ```kusto APL equivalent theme={null}
      | extend timestamp=unixtime_milliseconds_todatetime(epoch_ms)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    The function plays the same role as `FROM_UNIXTIME()` or `TO_TIMESTAMP()` in SQL dialects. In APL, you don’t divide by 1,000 because the function expects milliseconds.

    <CodeGroup>
      ```sql SQL example theme={null}
      SELECT FROM_UNIXTIME(epoch_ms/1000) AS timestamp FROM requests;
      ```

      ```kusto APL equivalent theme={null}
      ['sample-http-logs']
      | extend timestamp=unixtime_milliseconds_todatetime(epoch_ms)
      ```
    </CodeGroup>
  </Accordion>
</AccordionGroup>

## Usage

### Syntax

```kusto theme={null}
unixtime_milliseconds_todatetime(milliseconds)
```

### Parameters

| Name           | Type            | Description                                                             |
| -------------- | --------------- | ----------------------------------------------------------------------- |
| `milliseconds` | `int` or `long` | Whole milliseconds since the Unix epoch. Fractional input is truncated. |

### Returns

A `datetime` value that represents the given epoch milliseconds at UTC precision (1 millisecond).

## Use case example

The HTTP access logs keep the timestamp as epoch milliseconds and you want to convert the values to datetime.

**Query**

```kusto theme={null}
['sample-http-logs']
| extend epoch_milliseconds = toint(datetime_diff('Millisecond', _time, datetime(1970-01-01)))
| extend datetime_standard = unixtime_milliseconds_todatetime(epoch_milliseconds)
| project _time, epoch_milliseconds, datetime_standard
```

[Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'sample-http-logs'%5D%20%7C%20extend%20epoch_milliseconds%20%3D%20toint\(datetime_diff\('Millisecond'%2C%20_time%2C%20datetime\(1970-01-01\)\)\)%20%7C%20extend%20datetime_standard%20%3D%20unixtime_milliseconds_todatetime\(epoch_milliseconds\)%20%7C%20project%20_time%2C%20epoch_milliseconds%2C%20datetime_standard%22%7D)

**Output**

| \_time           | epoch\_milliseconds | datetime\_standard   |
| ---------------- | ------------------- | -------------------- |
| May 15, 12:09:22 | 1,747,303,762       | 2025-05-15T10:09:22Z |

This query converts the timestamp to epoch milliseconds and then back to datetime for demonstration purposes.

## List of related functions

* [unixtime\_microseconds\_todatetime](/apl/scalar-functions/datetime-functions/unixtime-microseconds-todatetime): Converts a Unix timestamp expressed in whole microseconds to an APL `datetime` value.
* [unixtime\_nanoseconds\_todatetime](/apl/scalar-functions/datetime-functions/unixtime-nanoseconds-todatetime): Converts a Unix timestamp expressed in whole nanoseconds to an APL `datetime` value.
* [unixtime\_seconds\_todatetime](/apl/scalar-functions/datetime-functions/unixtime-seconds-todatetime): Converts a Unix timestamp expressed in whole seconds to an APL `datetime` value.