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

# setDailyLang()

> Sets the language for the call.

`setDailyLang(lang)`

<Badge color="green">{"✓"} Prebuilt</Badge> <Badge color="green">{"✓"} Custom</Badge>

Sets the language for the call.

<Note>
  **Behavior differs by mode:**

  * **Prebuilt**: updates all UI text immediately.
  * **Custom call object**: stores the language preference internally with no automatic visual effect — you control your own UI. The [`lang-updated`](/reference/daily-js/events/iframe-ui-events#lang-updated) event still fires and [`getDailyLang()`](/reference/daily-js/instance-methods/get-daily-lang) will return the updated value. This is useful for reading language configuration set at the room or domain level and applying it to your own UI.
</Note>

The language can also be set at the domain, room, or token level. See [Changing the language in Daily Prebuilt](/docs/prebuilt/language) for the full guide including priority order.

## Parameters

<ParamField body="lang" type="DailyLanguageSetting" required>
  A language code or `'user'`. Supported values:

  | Value     | Language                                                                        |
  | --------- | ------------------------------------------------------------------------------- |
  | `'da'`    | Danish                                                                          |
  | `'de'`    | German                                                                          |
  | `'en'`    | English                                                                         |
  | `'es'`    | Spanish                                                                         |
  | `'fi'`    | Finnish                                                                         |
  | `'fr'`    | French                                                                          |
  | `'it'`    | Italian                                                                         |
  | `'jp'`    | Japanese                                                                        |
  | `'ka'`    | Georgian                                                                        |
  | `'nl'`    | Dutch                                                                           |
  | `'no'`    | Norwegian                                                                       |
  | `'pl'`    | Polish                                                                          |
  | `'pt'`    | Portuguese (Portugal)                                                           |
  | `'pt-BR'` | Portuguese (Brazil)                                                             |
  | `'ru'`    | Russian                                                                         |
  | `'sv'`    | Swedish                                                                         |
  | `'tr'`    | Turkish                                                                         |
  | `'user'`  | Follow the browser's language preference (falls back to English if unsupported) |
</ParamField>

## Return value

Returns `this` for chaining.

## Example

```javascript theme={null}
call.setDailyLang('fr');

call.on('lang-updated', ({ lang, langSetting }) => {
  console.log('Language in effect:', lang);       // 'fr'
  console.log('Language setting:', langSetting);  // 'fr'
});
```

## See also

<CardGroup>
  <Card title="Types" icon="t" iconType="solid">
    * [DailyCallOptions: lang](/reference/daily-js/types/daily-call-options#param-lang)
  </Card>

  <Card title="Methods" icon="code" iconType="solid">
    * [getDailyLang()](/reference/daily-js/instance-methods/get-daily-lang)
  </Card>

  <Card title="Events" icon="bolt" iconType="solid">
    * [lang-updated](/reference/daily-js/events/iframe-ui-events#lang-updated)
  </Card>
</CardGroup>