diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52fe0a4f..0f03e8b4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 2.3.0
+
+- Add `supportedLocales` property that can be used to fill `MaterialApp`'s `supportedLocales` argument.
+
 ## 2.2.1
 
 - Fix compilation error occurring when non-standard name (not 'strings.i18n.json') is used for json files.
diff --git a/README.md b/README.md
index 1d89275e..75caf465 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ Lightweight i18n solution. Use JSON files to create typesafe translations.
 
 ```yaml
 dependencies:
-  fast_i18n: ^2.2.1
+  fast_i18n: ^2.3.0
 
 dev_dependencies:
   build_runner: any
diff --git a/example/README.md b/example/README.md
index ab22676c..8ff9c4f4 100644
--- a/example/README.md
+++ b/example/README.md
@@ -4,7 +4,7 @@
 
 ```yaml
 dependencies:
-  fast_i18n: ^2.2.1
+  fast_i18n: ^2.3.0
 
 dev_dependencies:
   build_runner: any
@@ -67,6 +67,19 @@ void initState() {
 }
 ```
 
+## Step 4a: Override 'supportedLocales'
+
+```dart
+MaterialApp(
+  localizationsDelegates: const [
+    GlobalMaterialLocalizations.delegate,
+    GlobalWidgetsLocalizations.delegate,
+    GlobalCupertinoLocalizations.delegate,
+  ],
+  supportedLocales: LocaleSettings.supportedLocales, // <---
+)
+```
+
 ## Step 4b: iOS-only
 
 ```
diff --git a/lib/builder.dart b/lib/builder.dart
index a79f2acc..e513f2da 100644
--- a/lib/builder.dart
+++ b/lib/builder.dart
@@ -23,24 +23,27 @@ class I18nBuilder implements Builder {
 
   bool _generated = false;
 
-  String get inputFilePattern => options.config['input_file_pattern'] ?? defaultInputFilePattern;
-  String get outputFilePattern => options.config['output_file_pattern'] ?? defaultOutputFilePattern;
+  String get inputFilePattern =>
+      options.config['input_file_pattern'] ?? defaultInputFilePattern;
+  String get outputFilePattern =>
+      options.config['output_file_pattern'] ?? defaultOutputFilePattern;
 
   @override
   FutureOr<void> build(BuildStep buildStep) async {
-    final String baseLocale = Utils.normalize(options.config['base_locale'] ?? defaultBaseLocale);
+    final String baseLocale =
+        Utils.normalize(options.config['base_locale'] ?? defaultBaseLocale);
     final String inputDirectory = options.config['input_directory'];
     final String outputDirectory = options.config['output_directory'];
-    final String translateVar = options.config['output_translate_var'] ?? defaultTranslateVar;
+    final String translateVar =
+        options.config['output_translate_var'] ?? defaultTranslateVar;
     final String keyCase = options.config['key_case'];
     final List<String> maps = options.config['maps']?.cast<String>() ?? [];
 
-    if (inputDirectory != null && !buildStep.inputId.path.contains(inputDirectory))
-      return;
+    if (inputDirectory != null &&
+        !buildStep.inputId.path.contains(inputDirectory)) return;
 
     // only generate once
-    if (_generated)
-      return;
+    if (_generated) return;
 
     _generated = true;
 
@@ -53,7 +56,8 @@ class I18nBuilder implements Builder {
         : Glob('**$inputFilePattern');
 
     await buildStep.findAssets(findAssetsPattern).forEach((assetId) {
-      final fileNameNoExtension = assetId.pathSegments.last.replaceAll(inputFilePattern, '');
+      final fileNameNoExtension =
+          assetId.pathSegments.last.replaceAll(inputFilePattern, '');
       final match = Utils.localeRegex.firstMatch(fileNameNoExtension);
 
       if (match != null) {
@@ -77,12 +81,11 @@ class I18nBuilder implements Builder {
 
     // build config which applies to all locales
     final config = I18nConfig(
-      baseName: baseName ?? defaultBaseName,
-      baseLocale: baseLocale,
-      maps: maps,
-      keyCase: keyCase,
-      translateVariable: translateVar
-    );
+        baseName: baseName ?? defaultBaseName,
+        baseLocale: baseLocale,
+        maps: maps,
+        keyCase: keyCase,
+        translateVariable: translateVar);
 
     // map each assetId to I18nData
     final localesWithData = Map<AssetId, I18nData>();
@@ -96,23 +99,24 @@ class I18nBuilder implements Builder {
 
     // generate
     final String output = generate(
-      config: config,
-      translations: localesWithData.values.toList()..sort((a, b) => a.locale.compareTo(b.locale))
-    );
+        config: config,
+        translations: localesWithData.values.toList()
+          ..sort((a, b) => a.locale.compareTo(b.locale)));
 
     // write only to main locale
-    final AssetId baseId = localesWithData.entries
-        .firstWhere((element) => element.value.base)
-        .key;
+    final AssetId baseId =
+        localesWithData.entries.firstWhere((element) => element.value.base).key;
 
-    final finalOutputDirectory = outputDirectory ?? (baseId.pathSegments..removeLast()).join('/');
-    final String outFilePath = '$finalOutputDirectory/$baseName$outputFilePattern';
+    final finalOutputDirectory =
+        outputDirectory ?? (baseId.pathSegments..removeLast()).join('/');
+    final String outFilePath =
+        '$finalOutputDirectory/$baseName$outputFilePattern';
 
     File(outFilePath).writeAsStringSync(output);
   }
 
   @override
   get buildExtensions => {
-    inputFilePattern: [outputFilePattern],
-  };
+        inputFilePattern: [outputFilePattern],
+      };
 }
diff --git a/lib/fast_i18n.dart b/lib/fast_i18n.dart
index 8b3b063f..30170726 100644
--- a/lib/fast_i18n.dart
+++ b/lib/fast_i18n.dart
@@ -1,19 +1,20 @@
 library fast_i18n;
 
 import 'dart:io';
+import 'dart:ui';
 
 import 'package:fast_i18n/utils.dart';
 
 class FastI18n {
+  static const _localePartsDelimiter = '-';
 
-  /// returns the locale string used by the device
-  static String getDeviceLocale() {
-    return Platform.localeName;
-  }
+  /// Returns the locale string used by the device.
+  static String getDeviceLocale() => Platform.localeName;
 
-  /// returns the candidate (or part of it) if it is supported
-  /// fallback to base locale
-  static String selectLocale(String candidate, List<String> supported, String baseLocale) {
+  /// Returns the candidate (or part of it) if it is supported.
+  /// Fallbacks to base locale.
+  static String selectLocale(
+      String candidate, List<String> supported, String baseLocale) {
     // normalize
     candidate = Utils.normalize(candidate);
 
@@ -23,7 +24,7 @@ class FastI18n {
     if (selected != null) return selected;
 
     // 2nd try: match the first part (language)
-    List<String> deviceLocaleParts = candidate.split('-');
+    List<String> deviceLocaleParts = candidate.split(_localePartsDelimiter);
     selected = supported.firstWhere(
         (element) => element == deviceLocaleParts.first,
         orElse: () => null);
@@ -38,4 +39,40 @@ class FastI18n {
     // fallback: default locale
     return baseLocale;
   }
+
+  /// Converts the passed locales from [String] to [Locale].
+  /// Puts the [baseLocale] into the the beginning of the list.
+  static List<Locale> convertToLocales(
+      List<String> locales, String baseLocale) {
+    final rawSupportedLocales = [
+      baseLocale,
+      ...locales.where((locale) => locale != baseLocale),
+    ];
+
+    final supportedLocales = rawSupportedLocales.map((rawLocale) {
+      if (rawLocale.contains(_localePartsDelimiter)) {
+        final localeParts = rawLocale
+            .split(_localePartsDelimiter)
+            .where((part) => part.isNotEmpty)
+            .toList();
+        if (localeParts.length == 2) {
+          return Locale.fromSubtags(
+              languageCode: localeParts[0], countryCode: localeParts[1]);
+        } else if (localeParts.length == 3) {
+          return Locale.fromSubtags(
+            languageCode: localeParts[0],
+            scriptCode: localeParts[1],
+            countryCode: localeParts[2],
+          );
+        } else {
+          throw Exception(
+              "The locale '$rawLocale' is not in a supported format. Examples of the supported formats: 'en', 'en-US', 'zh-Hans-CN'.");
+        }
+      } else {
+        return Locale.fromSubtags(languageCode: rawLocale);
+      }
+    }).toList();
+
+    return supportedLocales;
+  }
 }
diff --git a/lib/src/generator.dart b/lib/src/generator.dart
index 5a7f228c..e1ae2227 100644
--- a/lib/src/generator.dart
+++ b/lib/src/generator.dart
@@ -36,7 +36,8 @@ String generate({I18nConfig config, List<I18nData> translations}) {
 
 /// generates the header of the .g.dart file
 /// contains the t function, LocaleSettings class and some global variables
-void _generateHeader(StringBuffer buffer, I18nConfig config, List<I18nData> allLocales) {
+void _generateHeader(
+    StringBuffer buffer, I18nConfig config, List<I18nData> allLocales) {
   // identifiers
   const String mapVar = '_strings';
   const String baseLocaleVar = '_baseLocale';
@@ -77,8 +78,10 @@ void _generateHeader(StringBuffer buffer, I18nConfig config, List<I18nData> allL
   buffer.writeln();
   buffer.writeln('/// Method A: Simple');
   buffer.writeln('///');
-  buffer.writeln('/// Widgets using this method will not be updated when locale changes during runtime.');
-  buffer.writeln('/// Translation happens during initialization of the widget (call of t).');
+  buffer.writeln(
+      '/// Widgets using this method will not be updated when locale changes during runtime.');
+  buffer.writeln(
+      '/// Translation happens during initialization of the widget (call of t).');
   buffer.writeln('///');
   buffer.writeln('/// Usage:');
   buffer.writeln('/// String translated = t.someKey.anotherKey;');
@@ -88,8 +91,10 @@ void _generateHeader(StringBuffer buffer, I18nConfig config, List<I18nData> allL
   buffer.writeln();
   buffer.writeln('/// Method B: Advanced');
   buffer.writeln('///');
-  buffer.writeln('/// All widgets using this method will trigger a rebuild when locale changes.');
-  buffer.writeln('/// Use this if you have e.g. a settings page where the user can select the locale during runtime.');
+  buffer.writeln(
+      '/// All widgets using this method will trigger a rebuild when locale changes.');
+  buffer.writeln(
+      '/// Use this if you have e.g. a settings page where the user can select the locale during runtime.');
   buffer.writeln('///');
   buffer.writeln('/// Step 1:');
   buffer.writeln('/// wrap your App with');
@@ -98,13 +103,16 @@ void _generateHeader(StringBuffer buffer, I18nConfig config, List<I18nData> allL
   buffer.writeln('/// );');
   buffer.writeln('///');
   buffer.writeln('/// Step 2:');
-  buffer.writeln('/// final t = $translationsClass.of(context); // get t variable');
-  buffer.writeln('/// String translated = t.someKey.anotherKey; // use t variable');
+  buffer.writeln(
+      '/// final t = $translationsClass.of(context); // get t variable');
+  buffer.writeln(
+      '/// String translated = t.someKey.anotherKey; // use t variable');
   buffer.writeln('class $translationsClass {');
   buffer.writeln('\t$translationsClass._(); // no constructor');
   buffer.writeln();
   buffer.writeln('\tstatic $baseClassName of(BuildContext context) {');
-  buffer.writeln('\t\treturn context.dependOnInheritedWidgetOfExactType<$inheritedClass>().translations;');
+  buffer.writeln(
+      '\t\treturn context.dependOnInheritedWidgetOfExactType<$inheritedClass>().translations;');
   buffer.writeln('\t}');
   buffer.writeln('}');
 
@@ -114,7 +122,7 @@ void _generateHeader(StringBuffer buffer, I18nConfig config, List<I18nData> allL
   buffer.writeln('\t$settingsClass._(); // no constructor');
 
   buffer.writeln();
-  buffer.writeln('\t/// Use locale of the device, fallbacks to base locale.');
+  buffer.writeln('\t/// Uses locale of the device, fallbacks to base locale.');
   buffer.writeln('\t/// Returns the locale which has been set.');
   buffer.writeln('\tstatic String useDeviceLocale() {');
   buffer.writeln('\t\tString deviceLocale = FastI18n.getDeviceLocale();');
@@ -122,54 +130,67 @@ void _generateHeader(StringBuffer buffer, I18nConfig config, List<I18nData> allL
   buffer.writeln('\t}');
 
   buffer.writeln();
-  buffer.writeln('\t/// Set locale, fallbacks to base locale.');
+  buffer.writeln('\t/// Sets locale, fallbacks to base locale.');
   buffer.writeln('\t/// Returns the locale which has been set.');
   buffer.writeln('\tstatic String setLocale(String locale) {');
-  buffer.writeln('\t\t$localeVar = FastI18n.selectLocale(locale, $mapVar.keys.toList(), $baseLocaleVar);');
+  buffer.writeln(
+      '\t\t$localeVar = FastI18n.selectLocale(locale, $mapVar.keys.toList(), $baseLocaleVar);');
   buffer.writeln('\t\t$translateVar = $mapVar[$localeVar];');
   buffer.writeln();
   buffer.writeln('\t\tif ($translationProviderKey.currentState != null) {');
-  buffer.writeln('\t\t\t$translationProviderKey.currentState.setLocale($localeVar);');
+  buffer.writeln(
+      '\t\t\t$translationProviderKey.currentState.setLocale($localeVar);');
   buffer.writeln('\t\t}');
   buffer.writeln();
   buffer.writeln('\t\treturn $localeVar;');
   buffer.writeln('\t}');
 
   buffer.writeln();
-  buffer.writeln('\t/// Get current locale.');
+  buffer.writeln('\t/// Gets current locale.');
   buffer.writeln('\tstatic String get currentLocale {');
   buffer.writeln('\t\treturn $localeVar;');
   buffer.writeln('\t}');
 
   buffer.writeln();
-  buffer.writeln('\t/// Get base locale.');
+  buffer.writeln('\t/// Gets base locale.');
   buffer.writeln('\tstatic String get baseLocale {');
   buffer.writeln('\t\treturn $baseLocaleVar;');
   buffer.writeln('\t}');
 
   buffer.writeln();
-  buffer.writeln('\t/// Get supported locales.');
+  buffer.writeln('\t/// Gets supported locales.');
   buffer.writeln('\tstatic List<String> get locales {');
   buffer.writeln('\t\treturn $mapVar.keys.toList();');
   buffer.writeln('\t}');
 
+  buffer.writeln();
+  buffer.writeln('\t/// Get supported locales with base locale sorted first.');
+  buffer.writeln('\tstatic List<Locale> get supportedLocales {');
+  buffer.writeln(
+      '\t\treturn FastI18n.convertToLocales($mapVar.keys.toList(), $baseLocaleVar);');
+  buffer.writeln('\t}');
+
   buffer.writeln('}');
 
   // TranslationProvider
   buffer.writeln();
-  buffer.writeln('GlobalKey<$translationProviderStateClass> $translationProviderKey = new GlobalKey<$translationProviderStateClass>();');
+  buffer.writeln(
+      'GlobalKey<$translationProviderStateClass> $translationProviderKey = new GlobalKey<$translationProviderStateClass>();');
   buffer.writeln();
   buffer.writeln('class $translationProviderClass extends StatefulWidget {');
-  buffer.writeln('\t$translationProviderClass({@required this.child}) : super(key: $translationProviderKey);');
+  buffer.writeln(
+      '\t$translationProviderClass({@required this.child}) : super(key: $translationProviderKey);');
   buffer.writeln();
   buffer.writeln('\tfinal Widget child;');
   buffer.writeln();
   buffer.writeln('\t@override');
-  buffer.writeln('\t$translationProviderStateClass createState() => $translationProviderStateClass();');
+  buffer.writeln(
+      '\t$translationProviderStateClass createState() => $translationProviderStateClass();');
   buffer.writeln('}');
 
   buffer.writeln();
-  buffer.writeln('class $translationProviderStateClass extends State<$translationProviderClass> {');
+  buffer.writeln(
+      'class $translationProviderStateClass extends State<$translationProviderClass> {');
   buffer.writeln('\tString locale = $localeVar;');
   buffer.writeln();
   buffer.writeln('\tvoid setLocale(String newLocale) {');
@@ -191,7 +212,8 @@ void _generateHeader(StringBuffer buffer, I18nConfig config, List<I18nData> allL
   buffer.writeln();
   buffer.writeln('class $inheritedClass extends InheritedWidget {');
   buffer.writeln('\tfinal $baseClassName translations;');
-  buffer.writeln('\t$inheritedClass({this.translations, Widget child}) : super(child: child);');
+  buffer.writeln(
+      '\t$inheritedClass({this.translations, Widget child}) : super(child: child);');
   buffer.writeln();
   buffer.writeln('\t@override');
   buffer.writeln('\tbool updateShouldNotify($inheritedClass oldWidget) {');
@@ -203,7 +225,8 @@ void _generateHeader(StringBuffer buffer, I18nConfig config, List<I18nData> allL
 /// generates all classes of one locale
 /// all non-default locales has a postfix of their locale code
 /// e.g. Strings, StringsDe, StringsFr
-void _generateLocale(StringBuffer buffer, I18nConfig config, I18nData localeData) {
+void _generateLocale(
+    StringBuffer buffer, I18nConfig config, I18nData localeData) {
   Queue<ClassTask> queue = Queue();
 
   queue.add(ClassTask(
@@ -221,7 +244,7 @@ void _generateLocale(StringBuffer buffer, I18nConfig config, I18nData localeData
       buffer,
       queue,
       task.className,
-      task.members
+      task.members,
     );
   } while (queue.isNotEmpty);
 }
@@ -235,11 +258,10 @@ void _generateClass(
   StringBuffer buffer,
   Queue<ClassTask> queue,
   String className,
-  Map<String, Value> currMembers
+  Map<String, Value> currMembers,
 ) {
-  String finalClassName = base
-      ? className
-      : className + locale.capitalize().replaceAll('-', '');
+  String finalClassName =
+      base ? className : className + locale.capitalize().replaceAll('-', '');
 
   buffer.writeln();
 
@@ -265,7 +287,8 @@ void _generateClass(
       if (value.params.isEmpty) {
         buffer.writeln('String $key = \'${value.content}\';');
       } else {
-        buffer.writeln('String $key${_toParameterList(value.params)} => \'${value.content}\';');
+        buffer.writeln(
+            'String $key${_toParameterList(value.params)} => \'${value.content}\';');
       }
     } else if (value is ListNode) {
       String type = value.plainStrings ? 'String' : 'dynamic';
@@ -287,7 +310,8 @@ void _generateClass(
             ? childClassName
             : childClassName + locale.capitalize().replaceAll('-', '');
 
-        buffer.writeln('$finalChildClassName get $key => $finalChildClassName._instance;');
+        buffer.writeln(
+            '$finalChildClassName get $key => $finalChildClassName._instance;');
       }
     }
   });
@@ -298,13 +322,14 @@ void _generateClass(
 /// generates a map of ONE locale
 /// similar to _generateClass but anonymous and accessible via key
 void _generateMap(
-    bool base,
-    String locale,
-    StringBuffer buffer,
-    Queue<ClassTask> queue,
-    String className,
-    Map<String, Value> currMembers,
-    int depth) {
+  bool base,
+  String locale,
+  StringBuffer buffer,
+  Queue<ClassTask> queue,
+  String className,
+  Map<String, Value> currMembers,
+  int depth,
+) {
   buffer.writeln('{');
 
   currMembers.forEach((key, value) {
@@ -313,17 +338,20 @@ void _generateMap(
       if (value.params.isEmpty) {
         buffer.writeln('\'$key\': \'${value.content}\',');
       } else {
-        buffer.writeln('\'$key\': ${_toParameterList(value.params)} => \'${value.content}\',');
+        buffer.writeln(
+            '\'$key\': ${_toParameterList(value.params)} => \'${value.content}\',');
       }
     } else if (value is ListNode) {
       buffer.write('\'$key\': ');
-      _generateList(base, locale, buffer, queue, className, value.entries, depth + 1);
+      _generateList(
+          base, locale, buffer, queue, className, value.entries, depth + 1);
     } else if (value is ObjectNode) {
       String childClassName = className + key.capitalize();
       if (value.mapMode) {
         // inline map
         buffer.write('\'$key\': ');
-        _generateMap(base, locale, buffer, queue, childClassName, value.entries, depth + 1);
+        _generateMap(base, locale, buffer, queue, childClassName, value.entries,
+            depth + 1);
       } else {
         // generate a class later on
         queue.add(ClassTask(childClassName, value.entries));
@@ -349,8 +377,15 @@ void _generateMap(
 }
 
 /// generates a list
-void _generateList(bool base, String locale, StringBuffer buffer,
-    Queue<ClassTask> queue, String className, List<Value> currList, int depth) {
+void _generateList(
+  bool base,
+  String locale,
+  StringBuffer buffer,
+  Queue<ClassTask> queue,
+  String className,
+  List<Value> currList,
+  int depth,
+) {
   buffer.writeln('[');
 
   for (int i = 0; i < currList.length; i++) {
@@ -360,10 +395,12 @@ void _generateList(bool base, String locale, StringBuffer buffer,
       if (value.params.isEmpty) {
         buffer.writeln('\'${value.content}\',');
       } else {
-        buffer.writeln('${_toParameterList(value.params)} => \'${value.content}\',');
+        buffer.writeln(
+            '${_toParameterList(value.params)} => \'${value.content}\',');
       }
     } else if (value is ListNode) {
-      _generateList(base, locale, buffer, queue, className, value.entries, depth + 1);
+      _generateList(
+          base, locale, buffer, queue, className, value.entries, depth + 1);
     } else if (value is ObjectNode) {
       String childClassName = className + depth.toString() + 'i' + i.toString();
       queue.add(ClassTask(childClassName, value.entries));
@@ -421,8 +458,10 @@ extension on String {
 
   String toCase(String caseName) {
     switch (caseName) {
-      case 'snake': return snakeCase;
-      case 'camel': return camelCase;
+      case 'snake':
+        return snakeCase;
+      case 'camel':
+        return camelCase;
       default:
         return this;
     }
diff --git a/lib/src/model.dart b/lib/src/model.dart
index 95bcfcaa..06d2eeeb 100644
--- a/lib/src/model.dart
+++ b/lib/src/model.dart
@@ -8,7 +8,13 @@ class I18nConfig {
   final String keyCase;
   final String translateVariable;
 
-  I18nConfig({this.baseName, this.baseLocale, this.maps, this.keyCase, this.translateVariable});
+  I18nConfig({
+    this.baseName,
+    this.baseLocale,
+    this.maps,
+    this.keyCase,
+    this.translateVariable,
+  });
 
   @override
   String toString() => '$baseLocale, maps: $maps';
@@ -80,8 +86,7 @@ class TextNode extends Value {
 /// 'my name is $name and I am $age years old' => ['name', 'age']
 /// 'my name is ${name} and I am ${age} years old' => ['name', 'age']
 List<String> _findArguments(String content) {
-  return Utils
-      .argumentsRegex
+  return Utils.argumentsRegex
       .allMatches(content)
       .map((e) => e.group(2))
       .toList();
diff --git a/lib/src/parser_json.dart b/lib/src/parser_json.dart
index 5c97d455..b42a6192 100644
--- a/lib/src/parser_json.dart
+++ b/lib/src/parser_json.dart
@@ -4,7 +4,8 @@ import 'package:fast_i18n/src/model.dart';
 
 /// parses a json of one locale
 /// returns an I18nData object
-I18nData parseJSON(I18nConfig config, String baseName, String locale, String content) {
+I18nData parseJSON(
+    I18nConfig config, String baseName, String locale, String content) {
   Map<String, dynamic> map = json.decode(content);
   Map<String, Value> destination = Map();
   _parseJSONObject(config.maps, map, destination, []);
@@ -12,11 +13,16 @@ I18nData parseJSON(I18nConfig config, String baseName, String locale, String con
   return I18nData(
     base: config.baseLocale == locale,
     locale: locale,
-    root: ObjectNode(destination, false)
+    root: ObjectNode(destination, false),
   );
 }
 
-void _parseJSONObject(List<String> maps, Map<String, dynamic> curr, Map<String, Value> destination, List<String> stack) {
+void _parseJSONObject(
+  List<String> maps,
+  Map<String, dynamic> curr,
+  Map<String, Value> destination,
+  List<String> stack,
+) {
   curr.forEach((key, value) {
     if (value is String) {
       // key: 'value'
@@ -38,7 +44,12 @@ void _parseJSONObject(List<String> maps, Map<String, dynamic> curr, Map<String,
   });
 }
 
-void _parseJSONArray(List<String> maps, List<dynamic> curr, List<Value> destination, List<String> stack) {
+void _parseJSONArray(
+  List<String> maps,
+  List<dynamic> curr,
+  List<Value> destination,
+  List<String> stack,
+) {
   for (dynamic value in curr) {
     if (value is String) {
       // key: 'value'
diff --git a/lib/utils.dart b/lib/utils.dart
index 2c6dfbb8..ef41da11 100644
--- a/lib/utils.dart
+++ b/lib/utils.dart
@@ -3,7 +3,8 @@ class Utils {
 
   /// finds the parts of the locale
   /// must start with an underscore
-  static RegExp localeRegex = RegExp(r'^((\w+)_)?([a-z]{2})([-_]([a-zA-Z]{2}))?$');
+  static RegExp localeRegex =
+      RegExp(r'^((\w+)_)?([a-z]{2})([-_]([a-zA-Z]{2}))?$');
 
   /// returns the locale with the following syntax:
   /// - all lowercase
diff --git a/pubspec.yaml b/pubspec.yaml
index 6436b1b0..49ce2fd7 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: fast_i18n
 description: Lightweight i18n solution. Use JSON files to create typesafe translations.
-version: 2.2.1
+version: 2.3.0
 homepage: https://github.com/Tienisto/flutter-fast-i18n
 
 environment:
diff --git a/test/fast_i18n_test.dart b/test/fast_i18n_test.dart
index 20a8bbe4..7a641af1 100644
--- a/test/fast_i18n_test.dart
+++ b/test/fast_i18n_test.dart
@@ -35,4 +35,69 @@ void testSelectLocale() {
       expect(FastI18n.selectLocale('fr', ['en', 'de'], 'cz'), 'cz');
     });
   });
+
+  group('convertToLocales', () {
+    test('puts the base locale first', () {
+      final localesAsStrings = ['en-us', 'ru-RU', 'de-de', 'zh-Hans-CN'];
+      final baseLocaleString = 'ru-RU';
+
+      final locales =
+          FastI18n.convertToLocales(localesAsStrings, baseLocaleString);
+
+      expect(locales.length, 4);
+      expect(locales[0].toLanguageTag(), 'ru-RU');
+      expect(locales[1].toLanguageTag(), 'en-us');
+      expect(locales[2].toLanguageTag(), 'de-de');
+      expect(locales[3].toLanguageTag(), 'zh-Hans-CN');
+    });
+
+    test('when there is no country code present', () {
+      final localesAsStrings = ['en', 'ru-RU', 'de'];
+      final baseLocaleString = 'de';
+
+      final locales =
+          FastI18n.convertToLocales(localesAsStrings, baseLocaleString);
+
+      expect(locales.length, 3);
+      expect(locales[0].toLanguageTag(), 'de');
+      expect(locales[1].toLanguageTag(), 'en');
+      expect(locales[2].toLanguageTag(), 'ru-RU');
+    });
+
+    test(
+        "throws Exception if a locale with '-' delimiter doesn't have 2+ non-empty parts",
+        () {
+      final localesAsStrings = ['ru-', 'de'];
+      final baseLocaleString = 'de';
+
+      expect(
+        () => FastI18n.convertToLocales(localesAsStrings, baseLocaleString),
+        throwsA(isA<Exception>()),
+      );
+    });
+
+    test(
+        'throws AssertionError if primary language subtag is not present in the provided base locale',
+        () {
+      final localesAsStrings = ['en-us'];
+      final baseLocaleString = '';
+
+      expect(
+        () => FastI18n.convertToLocales(localesAsStrings, baseLocaleString),
+        throwsA(isA<AssertionError>()),
+      );
+    });
+
+    test(
+        'throws AssertionError if primary language subtag is not present in the provided locales',
+        () {
+      final localesAsStrings = ['en-us', ''];
+      final baseLocaleString = 'en-US';
+
+      expect(
+        () => FastI18n.convertToLocales(localesAsStrings, baseLocaleString),
+        throwsA(isA<AssertionError>()),
+      );
+    });
+  });
 }