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

# ETL: ToMilliSeconds

> Convert a datetime value to the number of milliseconds elapsed since the Unix epoch (1970-01-01T00:00:00Z). Use for timestamp arithmetic in ETL.

## Description

Returns the number of milliseconds elapsed since 1970-01-01T00:00:00Z for a datetime value.

## Syntax

`ToMilliSeconds(datetime_expression)`

## Examples

`ToMilliSeconds(ToDate('2015-02-04T13:27:23.950Z'))` returns `1423056443950`

## Return value datatype

Long

## Impact of null value

If datetime\_value is null, returns null.