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

# week_start_day

> Defines the day that weeks start on.

Defines the day that weeks start on. Defaults to `Monday`.

<Info>
  `OMNI_WEEK()` and `OMNI_DAY_OF_WEEK_NUMBER()` SQL operators are impacted by this setting.
</Info>

This parameter can be set dynamically using a [user attribute](/administration/users/attributes), which is useful when different users or regions follow different calendar conventions.

## Syntax

```yaml theme={null}
week_start_day: <day_of_week>
```

## Properties

<ParamField path="week_start_day" type="string" default="Monday">
  The day of the week that weeks start on. Valid values are: `Monday`, `Tuesday`, `Wednesday`, `Thursday`, `Friday`, `Saturday`, `Sunday`.

  Can be set dynamically using [user attributes](/administration/users/attributes). See the [**Examples**](#dynamic-value-using-user-attributes) section for an example.
</ParamField>

## Examples

### Static value

```yaml theme={null}
week_start_day: Sunday
```

### Dynamic value using user attributes

This example assumes your Omni instance has an existing user attribute called `week_start` and that users have been assigned appropriate day values, such as `Sunday` for US users or `Monday` for European users.

```yaml title="Set week start day based on user's region" theme={null}
week_start_day: {{ omni_attributes.week_start }}
```