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Expo Localization
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expo-localization allows you to Localize your app, customizing the experience for specific regions, languages, or cultures. It also provides access to the locale data on the native device. Using the popular library i18n-js with expo-localization will enable you to create a very accessible experience for users.

Platform Compatibility

Android Device	Android Emulator	iOS Device	iOS Simulator	Web

Installation

Terminal

- npx expo install expo-localization

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

Usage

Find more information about using expo-localization in the Localization guide.

API

import { getLocales, getCalendars } from 'expo-localization';

Behavior

You can use synchronous getLocales() and getCalendars() methods to get the locale settings of the user device. On iOS, the results will remain the same while the app is running.

On Android, the user can change locale preferences in Settings without restarting apps. To keep the localization current, you can rerun the getLocales() and getCalendars() methods every time the app returns to the foreground. Use AppState to detect this.

Constants

Deprecated. Use Localization.getLocales() instead. Three-character ISO 4217 currency code. Returns null on web.

`Localization.currency`

Type: null | string

Example

'USD', 'EUR', 'CNY', null

Deprecated. Use Localization.getLocales() instead. Decimal separator used for formatting numbers.

`Localization.decimalSeparator`

Type: string

Example

',', '.'

Deprecated. Use Localization.getLocales() instead. Digit grouping separator used when formatting numbers larger than 1000.

`Localization.digitGroupingSeparator`

Type: string

Example

'.', '', ','

Deprecated. Use Localization.getLocales() instead. Boolean value that indicates whether the system uses the metric system. On Android and web, this is inferred from the current region.

`Localization.isMetric`

Type: boolean

Deprecated. Use Localization.getLocales() instead. Returns if the system's language is written from Right-to-Left. This can be used to build features like bidirectional icons.

Returns false in Server Side Rendering (SSR) environments.

`Localization.isRTL`

Type: boolean

Deprecated. Use Localization.getLocales() instead. A list of all the supported language ISO codes.

`Localization.isoCurrencyCodes`

Type: string[]

`Localization.locale`

Type: string

Consider using Localization.getLocales() for a list of user preferred locales instead. An IETF BCP 47 language tag, consisting of a two-character language code and optional script, region and variant codes.

Example

'en', 'en-US', 'zh-Hans', 'zh-Hans-CN', 'en-emodeng'

Deprecated. Use Localization.getLocales() instead. List of all the native languages provided by the user settings. These are returned in the order the user defines in their device settings.

`Localization.locales`

Type: string[]

Example

['en', 'en-US', 'zh-Hans', 'zh-Hans-CN', 'en-emodeng']

Deprecated. Use Localization.getLocales() instead. The region code for your device that comes from the Region setting under Language & Region on iOS. This value is always available on iOS, but might return null on Android or web.

`Localization.region`

Type: null | string

Example

'US', 'NZ', null

Deprecated. Use Localization.getLocales() instead. The current time zone in display format. On Web time zone is calculated with Intl.DateTimeFormat().resolvedOptions().timeZone. For a better estimation you could use the moment-timezone package but it will add significant bloat to your website's bundle size.

`Localization.timezone`

Type: string

Example

'America/Los_Angeles'

Methods

`Localization.getCalendars()`

List of user's preferred calendars, returned as an array of objects of type Calendar. Guaranteed to contain at least 1 element. For now always returns a single element, but it's likely to return a user preference list on some platforms in the future.

Example

[ { "calendar": "gregory", "timeZone": "Europe/Warsaw", "uses24hourClock": true, "firstWeekday": 1 } ]

Returns

Calendar[]

`Localization.getLocales()`

List of user's locales, returned as an array of objects of type Locale. Guaranteed to contain at least 1 element. These are returned in the order the user defines in their device settings. On the web currency and measurements systems are not provided, instead returned as null. If needed, you can infer them from the current region using a lookup table.

Example

[{ "languageTag": "pl-PL", "languageCode": "pl", "textDirection": "ltr", "digitGroupingSeparator": " ", "decimalSeparator": ",", "measurementSystem": "metric", "currencyCode": "PLN", "currencySymbol": "zł", "regionCode": "PL" }]

Returns

Locale[]

Deprecated. Use Localization.getLocales() or Localization.getCalendars() instead.

`Localization.getLocalizationAsync()`

Get the latest native values from the device. Locale can be changed on some Android devices without resetting the app.

On iOS, changing the locale will cause the device to reset meaning the constants will always be correct.

Example

// When the app returns from the background on Android...

const { locale } = await Localization.getLocalizationAsync();

Returns

Promise<Localization>

Types

`Calendar`

Name	Type	Description
calendar	`CalendarIdentifier \| null`	The calendar identifier, one of Unicode calendar types. On Android is limited to one of device's available calendar types. On iOS uses calendar identifiers, but maps them to the corresponding Unicode types, will also never contain `'dangi'` or `'islamic-rgsa'` due to it not being implemented on iOS.
firstWeekday	`Weekday \| null`	The first day of the week. For most calendars Sunday is numbered `1`, with Saturday being number `7`. Can be null on some browsers that don't support the weekInfo property in Intl API. Example `1`, `7`.
timeZone	`string \| null`	Time zone for the calendar. Can be `null` on Web. Example `'America/Los_Angeles'`, `'Europe/Warsaw'`, `'GMT+1'`.
uses24hourClock	`boolean \| null`	True when current device settings use 24 hour time format. Can be null on some browsers that don't support the hourCycle property in Intl API.

`Locale`

Name	Type	Description
currencyCode	`string \| null`	Currency code for the locale. Is `null` on Web, use a table lookup based on region instead. Example `'USD'`, `'EUR'`, `'PLN'`.
currencySymbol	`string \| null`	Currency symbol for the locale. Is `null` on Web, use a table lookup based on region (if available) instead. Example `'$'`, `'€'`, `'zł'`.
decimalSeparator	`string \| null`	Decimal separator used for formatting numbers with fractional parts. Example `'.'`, `','`.
digitGroupingSeparator	`string \| null`	Digit grouping separator used for formatting large numbers. Example `'.'`, `','`.
languageCode	`string`	An IETF BCP 47 language tag without the region code. Example `'en'`, `'es'`, `'pl'`.
languageTag	`string`	An IETF BCP 47 language tag with a region code. Example `'en-US'`, `'es-419'`, `'pl-PL'`.
measurementSystem	`'metric' \| 'us' \| 'uk' \| null`	The measurement system used in the locale. On iOS is one of `'metric'`, `'us'`. On Android is one of `'metric'`, `'us'`, `'uk'`. Is `null` on Web, as user chosen measurement system is not exposed on the web and using locale to determine measurement systems is unreliable. Ask for user preferences if possible.
regionCode	`string \| null`	The region code for your device that comes from the Region setting under Language & Region on iOS, Region settings on Android and is parsed from locale on Web (can be `null` on Web).
textDirection	`'ltr' \| 'rtl' \| null`	Text direction for the locale. One of: `'ltr'`, `'rtl'`, but can also be `null` on some browsers without support for the textInfo property in Intl API.

`Localization`

Name	Type	Description
currency	`string \| null`	Three-character ISO 4217 currency code. Returns `null` on web. Example `'USD'`, `'EUR'`, `'CNY'`, `null`
decimalSeparator	`string`	Decimal separator used for formatting numbers. Example `','`, `'.'`
digitGroupingSeparator	`string`	Digit grouping separator used when formatting numbers larger than 1000. Example `'.'`, `''`, `','`
isMetric	`boolean`	Boolean value that indicates whether the system uses the metric system. On Android and web, this is inferred from the current region.
isRTL	`boolean`	Returns if the system's language is written from Right-to-Left. This can be used to build features like bidirectional icons. Returns `false` in Server Side Rendering (SSR) environments.
isoCurrencyCodes	`string[]`	A list of all the supported language ISO codes.
locale	`string`	An IETF BCP 47 language tag, consisting of a two-character language code and optional script, region and variant codes. Example `'en'`, `'en-US'`, `'zh-Hans'`, `'zh-Hans-CN'`, `'en-emodeng'`
locales	`string[]`	List of all the native languages provided by the user settings. These are returned in the order that the user defined in the device settings. Example `['en', 'en-US', 'zh-Hans', 'zh-Hans-CN', 'en-emodeng']`
region	`string \| null`	The region code for your device that comes from the Region setting under Language & Region on iOS. This value is always available on iOS, but might return `null` on Android or web. Example `'US'`, `'NZ'`, `null`
timezone	`string`	The current time zone in display format. On Web time zone is calculated with Intl.DateTimeFormat().resolvedOptions().timeZone. For a better estimation you could use the moment-timezone package but it will add significant bloat to your website's bundle size. Example `'America/Los_Angeles'`