diff --git a/assets/l10n/app_en.arb b/assets/l10n/app_en.arb
index 70417e356e..a9d9a686a2 100644
--- a/assets/l10n/app_en.arb
+++ b/assets/l10n/app_en.arb
@@ -526,9 +526,12 @@
   "@loginErrorMissingUsername": {
     "description": "Error message when an empty username was provided."
   },
-  "topicValidationErrorTooLong": "Topic length shouldn't be greater than 60 characters.",
+  "topicValidationErrorTooLong": "Topic length shouldn't be greater than {num, plural, =1{1 character} other{{num} characters}}.",
   "@topicValidationErrorTooLong": {
-    "description": "Topic validation error when topic is too long."
+    "description": "Topic validation error when topic is too long.",
+    "placeholders": {
+      "num": {"type": "int", "example": "60"}
+    }
   },
   "topicValidationErrorMandatoryButEmpty": "Topics are required in this organization.",
   "@topicValidationErrorMandatoryButEmpty": {
diff --git a/lib/api/model/initial_snapshot.dart b/lib/api/model/initial_snapshot.dart
index 5882122baa..43c91d4976 100644
--- a/lib/api/model/initial_snapshot.dart
+++ b/lib/api/model/initial_snapshot.dart
@@ -24,6 +24,8 @@ class InitialSnapshot {
 
   final List<CustomProfileField> customProfileFields;
 
+  final int maxTopicLength;
+
   /// The realm-level policy, on pre-FL 163 servers, for visibility of real email addresses.
   ///
   /// Search for "email_address_visibility" in https://zulip.com/api/register-queue.
@@ -123,6 +125,7 @@ class InitialSnapshot {
     required this.zulipMergeBase,
     required this.alertWords,
     required this.customProfileFields,
+    required this.maxTopicLength,
     required this.emailAddressVisibility,
     required this.serverTypingStartedExpiryPeriodMilliseconds,
     required this.serverTypingStoppedWaitPeriodMilliseconds,
diff --git a/lib/api/model/initial_snapshot.g.dart b/lib/api/model/initial_snapshot.g.dart
index 79cfbe5557..0d75baff83 100644
--- a/lib/api/model/initial_snapshot.g.dart
+++ b/lib/api/model/initial_snapshot.g.dart
@@ -22,6 +22,7 @@ InitialSnapshot _$InitialSnapshotFromJson(
       (json['custom_profile_fields'] as List<dynamic>)
           .map((e) => CustomProfileField.fromJson(e as Map<String, dynamic>))
           .toList(),
+  maxTopicLength: (json['max_topic_length'] as num).toInt(),
   emailAddressVisibility: $enumDecodeNullable(
     _$EmailAddressVisibilityEnumMap,
     json['email_address_visibility'],
@@ -115,6 +116,7 @@ Map<String, dynamic> _$InitialSnapshotToJson(InitialSnapshot instance) =>
       'zulip_merge_base': instance.zulipMergeBase,
       'alert_words': instance.alertWords,
       'custom_profile_fields': instance.customProfileFields,
+      'max_topic_length': instance.maxTopicLength,
       'email_address_visibility':
           _$EmailAddressVisibilityEnumMap[instance.emailAddressVisibility],
       'server_typing_started_expiry_period_milliseconds':
diff --git a/lib/api/route/messages.dart b/lib/api/route/messages.dart
index 5af312ce45..43552de94b 100644
--- a/lib/api/route/messages.dart
+++ b/lib/api/route/messages.dart
@@ -155,8 +155,6 @@ class GetMessagesResult {
   Map<String, dynamic> toJson() => _$GetMessagesResultToJson(this);
 }
 
-// https://zulip.com/api/send-message#parameter-topic
-const int kMaxTopicLengthCodePoints = 60;
 
 // https://zulip.com/api/send-message#parameter-content
 const int kMaxMessageLengthCodePoints = 10000;
diff --git a/lib/generated/l10n/zulip_localizations.dart b/lib/generated/l10n/zulip_localizations.dart
index 3203569966..5a2a6335f6 100644
--- a/lib/generated/l10n/zulip_localizations.dart
+++ b/lib/generated/l10n/zulip_localizations.dart
@@ -810,8 +810,8 @@ abstract class ZulipLocalizations {
   /// Topic validation error when topic is too long.
   ///
   /// In en, this message translates to:
-  /// **'Topic length shouldn\'t be greater than 60 characters.'**
-  String get topicValidationErrorTooLong;
+  /// **'Topic length shouldn\'t be greater than {num, plural, =1{1 character} other{{num} characters}}.'**
+  String topicValidationErrorTooLong(int num);
 
   /// Topic validation error when topic is required but was empty.
   ///
diff --git a/lib/generated/l10n/zulip_localizations_ar.dart b/lib/generated/l10n/zulip_localizations_ar.dart
index 20ad3cbe24..6b3557add4 100644
--- a/lib/generated/l10n/zulip_localizations_ar.dart
+++ b/lib/generated/l10n/zulip_localizations_ar.dart
@@ -408,7 +408,15 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   String get loginErrorMissingUsername => 'Please enter your username.';
 
   @override
-  String get topicValidationErrorTooLong => 'Topic length shouldn\'t be greater than 60 characters.';
+  String topicValidationErrorTooLong(int num) {
+    String _temp0 = intl.Intl.pluralLogic(
+      num,
+      locale: localeName,
+      other: '$num characters',
+      one: '1 character',
+    );
+    return 'Topic length shouldn\'t be greater than $_temp0.';
+  }
 
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
diff --git a/lib/generated/l10n/zulip_localizations_en.dart b/lib/generated/l10n/zulip_localizations_en.dart
index a88981fc26..7f181f5073 100644
--- a/lib/generated/l10n/zulip_localizations_en.dart
+++ b/lib/generated/l10n/zulip_localizations_en.dart
@@ -408,7 +408,15 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   String get loginErrorMissingUsername => 'Please enter your username.';
 
   @override
-  String get topicValidationErrorTooLong => 'Topic length shouldn\'t be greater than 60 characters.';
+  String topicValidationErrorTooLong(int num) {
+    String _temp0 = intl.Intl.pluralLogic(
+      num,
+      locale: localeName,
+      other: '$num characters',
+      one: '1 character',
+    );
+    return 'Topic length shouldn\'t be greater than $_temp0.';
+  }
 
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
diff --git a/lib/generated/l10n/zulip_localizations_ja.dart b/lib/generated/l10n/zulip_localizations_ja.dart
index be6eee8870..ec1ad123df 100644
--- a/lib/generated/l10n/zulip_localizations_ja.dart
+++ b/lib/generated/l10n/zulip_localizations_ja.dart
@@ -408,7 +408,15 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   String get loginErrorMissingUsername => 'Please enter your username.';
 
   @override
-  String get topicValidationErrorTooLong => 'Topic length shouldn\'t be greater than 60 characters.';
+  String topicValidationErrorTooLong(int num) {
+    String _temp0 = intl.Intl.pluralLogic(
+      num,
+      locale: localeName,
+      other: '$num characters',
+      one: '1 character',
+    );
+    return 'Topic length shouldn\'t be greater than $_temp0.';
+  }
 
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
diff --git a/lib/generated/l10n/zulip_localizations_nb.dart b/lib/generated/l10n/zulip_localizations_nb.dart
index 8e51c7a19b..eda227527f 100644
--- a/lib/generated/l10n/zulip_localizations_nb.dart
+++ b/lib/generated/l10n/zulip_localizations_nb.dart
@@ -408,7 +408,15 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   String get loginErrorMissingUsername => 'Please enter your username.';
 
   @override
-  String get topicValidationErrorTooLong => 'Topic length shouldn\'t be greater than 60 characters.';
+  String topicValidationErrorTooLong(int num) {
+    String _temp0 = intl.Intl.pluralLogic(
+      num,
+      locale: localeName,
+      other: '$num characters',
+      one: '1 character',
+    );
+    return 'Topic length shouldn\'t be greater than $_temp0.';
+  }
 
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
diff --git a/lib/generated/l10n/zulip_localizations_pl.dart b/lib/generated/l10n/zulip_localizations_pl.dart
index 0e4009a462..e03579f386 100644
--- a/lib/generated/l10n/zulip_localizations_pl.dart
+++ b/lib/generated/l10n/zulip_localizations_pl.dart
@@ -408,7 +408,9 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   String get loginErrorMissingUsername => 'Proszę podaj nazwę użytkownika.';
 
   @override
-  String get topicValidationErrorTooLong => 'Tytuł nie może być dłuższy niż 60 znaków.';
+  String topicValidationErrorTooLong(int num) {
+    return 'Tytuł nie może być dłuższy niż 60 znaków.';
+  }
 
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Wątki są wymagane przez tę organizację.';
diff --git a/lib/generated/l10n/zulip_localizations_ru.dart b/lib/generated/l10n/zulip_localizations_ru.dart
index f3ec9d623c..226e45c106 100644
--- a/lib/generated/l10n/zulip_localizations_ru.dart
+++ b/lib/generated/l10n/zulip_localizations_ru.dart
@@ -408,7 +408,9 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   String get loginErrorMissingUsername => 'Пожалуйста, введите ваше имя пользователя.';
 
   @override
-  String get topicValidationErrorTooLong => 'Длина темы не должна превышать 60 символов.';
+  String topicValidationErrorTooLong(int num) {
+    return 'Длина темы не должна превышать 60 символов.';
+  }
 
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Темы обязательны в этой организации.';
diff --git a/lib/generated/l10n/zulip_localizations_sk.dart b/lib/generated/l10n/zulip_localizations_sk.dart
index 6d22409eb5..7a808172e6 100644
--- a/lib/generated/l10n/zulip_localizations_sk.dart
+++ b/lib/generated/l10n/zulip_localizations_sk.dart
@@ -408,7 +408,15 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   String get loginErrorMissingUsername => 'Prosím zadajte prihlasovacie meno.';
 
   @override
-  String get topicValidationErrorTooLong => 'Topic length shouldn\'t be greater than 60 characters.';
+  String topicValidationErrorTooLong(int num) {
+    String _temp0 = intl.Intl.pluralLogic(
+      num,
+      locale: localeName,
+      other: '$num characters',
+      one: '1 character',
+    );
+    return 'Topic length shouldn\'t be greater than $_temp0.';
+  }
 
   @override
   String get topicValidationErrorMandatoryButEmpty => 'Topics are required in this organization.';
diff --git a/lib/model/store.dart b/lib/model/store.dart
index c3aaa501db..1b84b3c411 100644
--- a/lib/model/store.dart
+++ b/lib/model/store.dart
@@ -346,6 +346,7 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, UserStore, Channel
       realmEmptyTopicDisplayName: initialSnapshot.realmEmptyTopicDisplayName,
       realmDefaultExternalAccounts: initialSnapshot.realmDefaultExternalAccounts,
       customProfileFields: _sortCustomProfileFields(initialSnapshot.customProfileFields),
+      maxTopicLength: initialSnapshot.maxTopicLength,
       emailAddressVisibility: initialSnapshot.emailAddressVisibility,
       emoji: EmojiStoreImpl(
         realmUrl: realmUrl, allRealmEmoji: initialSnapshot.realmEmoji),
@@ -389,6 +390,7 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, UserStore, Channel
     required String? realmEmptyTopicDisplayName,
     required this.realmDefaultExternalAccounts,
     required this.customProfileFields,
+    required this.maxTopicLength,
     required this.emailAddressVisibility,
     required EmojiStoreImpl emoji,
     required this.accountId,
@@ -470,6 +472,8 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, UserStore, Channel
   }
   final String? _realmEmptyTopicDisplayName; // TODO(#668): update this realm setting
 
+  final int maxTopicLength;
+
   final Map<String, RealmDefaultExternalAccount> realmDefaultExternalAccounts;
   List<CustomProfileField> customProfileFields;
   /// For docs, please see [InitialSnapshot.emailAddressVisibility].
diff --git a/lib/widgets/compose_box.dart b/lib/widgets/compose_box.dart
index 1665227d51..655cde1c04 100644
--- a/lib/widgets/compose_box.dart
+++ b/lib/widgets/compose_box.dart
@@ -131,10 +131,10 @@ enum TopicValidationError {
   mandatoryButEmpty,
   tooLong;
 
-  String message(ZulipLocalizations zulipLocalizations) {
+  String message(ZulipLocalizations zulipLocalizations, {required int maxTopicLength}) {
     switch (this) {
       case tooLong:
-        return zulipLocalizations.topicValidationErrorTooLong;
+        return zulipLocalizations.topicValidationErrorTooLong(maxTopicLength);
       case mandatoryButEmpty:
         return zulipLocalizations.topicValidationErrorMandatoryButEmpty;
     }
@@ -143,6 +143,7 @@ enum TopicValidationError {
 
 class ComposeTopicController extends ComposeController<TopicValidationError> {
   ComposeTopicController({required this.store}) {
+    maxLengthUnicodeCodePoints = store.maxTopicLength;
     _update();
   }
 
@@ -151,8 +152,7 @@ class ComposeTopicController extends ComposeController<TopicValidationError> {
   // TODO(#668): listen to [PerAccountStore] once we subscribe to this value
   bool get mandatory => store.realmMandatoryTopics;
 
-  // TODO(#307) use `max_topic_length` instead of hardcoded limit
-  @override final maxLengthUnicodeCodePoints = kMaxTopicLengthCodePoints;
+  @override late int maxLengthUnicodeCodePoints;
 
   @override
   String _computeTextNormalized() {
@@ -1105,10 +1105,9 @@ class _SendButtonState extends State<_SendButton> {
     if (_hasValidationErrors) {
       final zulipLocalizations = ZulipLocalizations.of(context);
       List<String> validationErrorMessages = [
-        for (final error in (controller is StreamComposeBoxController
-                              ? controller.topic.validationErrors
-                              : const <TopicValidationError>[]))
-          error.message(zulipLocalizations),
+        if (controller is StreamComposeBoxController)
+          for (final error in controller.topic.validationErrors)
+            error.message(zulipLocalizations, maxTopicLength: controller.topic.maxLengthUnicodeCodePoints),
         for (final error in controller.content.validationErrors)
           error.message(zulipLocalizations),
       ];
diff --git a/test/example_data.dart b/test/example_data.dart
index d44849bc6a..0ce19ff8f3 100644
--- a/test/example_data.dart
+++ b/test/example_data.dart
@@ -897,6 +897,7 @@ InitialSnapshot initialSnapshot({
   String? zulipMergeBase,
   List<String>? alertWords,
   List<CustomProfileField>? customProfileFields,
+  int? maxTopicLength,
   EmailAddressVisibility? emailAddressVisibility,
   int? serverTypingStartedExpiryPeriodMilliseconds,
   int? serverTypingStoppedWaitPeriodMilliseconds,
@@ -927,6 +928,7 @@ InitialSnapshot initialSnapshot({
     zulipMergeBase: zulipMergeBase ?? recentZulipVersion,
     alertWords: alertWords ?? ['klaxon'],
     customProfileFields: customProfileFields ?? [],
+    maxTopicLength: maxTopicLength ?? 60,
     emailAddressVisibility: emailAddressVisibility ?? EmailAddressVisibility.everyone,
     serverTypingStartedExpiryPeriodMilliseconds:
       serverTypingStartedExpiryPeriodMilliseconds ?? 15000,
diff --git a/test/widgets/compose_box_test.dart b/test/widgets/compose_box_test.dart
index e02fd97a15..4161a40e7c 100644
--- a/test/widgets/compose_box_test.dart
+++ b/test/widgets/compose_box_test.dart
@@ -48,6 +48,7 @@ void main() {
     List<ZulipStream> streams = const [],
     bool? mandatoryTopics,
     int? zulipFeatureLevel,
+    int? maxTopicLength,
   }) async {
     if (narrow case ChannelNarrow(:var streamId) || TopicNarrow(: var streamId)) {
       assert(streams.any((stream) => stream.streamId == streamId),
@@ -60,6 +61,7 @@ void main() {
     await testBinding.globalStore.add(selfAccount, eg.initialSnapshot(
       zulipFeatureLevel: zulipFeatureLevel,
       realmMandatoryTopics: mandatoryTopics,
+      maxTopicLength: maxTopicLength,
     ));
 
     store = await testBinding.globalStore.perAccount(selfAccount.id);
@@ -286,41 +288,47 @@ void main() {
     });
 
     group('topic', () {
-      Future<void> prepareWithTopic(WidgetTester tester, String topic) async {
+      Future<void> prepareWithTopic(WidgetTester tester, String topic, int maxTopicLength) async {
         TypingNotifier.debugEnable = false;
         addTearDown(TypingNotifier.debugReset);
 
         final narrow = ChannelNarrow(channel.streamId);
-        await prepareComposeBox(tester, narrow: narrow, streams: [channel]);
+        await prepareComposeBox(tester, narrow: narrow, streams: [channel],
+          maxTopicLength: maxTopicLength);
         await enterTopic(tester, narrow: narrow, topic: topic);
         await enterContent(tester, 'some content');
       }
 
-      Future<void> checkErrorResponse(WidgetTester tester) async {
+      Future<void> checkErrorResponse(WidgetTester tester, {required int maxTopicLength}) async {
         await tester.tap(find.byWidget(checkErrorDialog(tester,
           expectedTitle: 'Message not sent',
-          expectedMessage: 'Topic length shouldn\'t be greater than 60 characters.')));
+          expectedMessage: 'Topic length shouldn\'t be greater than $maxTopicLength characters.')));
       }
 
+      final ValueVariant<int> maxTopicLengthVariants = ValueVariant<int>({50, 60, 70});
+
       testWidgets('too-long topic is rejected', (tester) async {
+        final maxTopicLength = maxTopicLengthVariants.currentValue!;
         await prepareWithTopic(tester,
-          makeStringWithCodePoints(kMaxTopicLengthCodePoints + 1));
+          makeStringWithCodePoints(maxTopicLength + 1), maxTopicLength);
         await tapSendButton(tester);
-        await checkErrorResponse(tester);
-      });
+        await checkErrorResponse(tester, maxTopicLength: maxTopicLength);
+      }, variant: maxTopicLengthVariants);
 
       testWidgets('max-length topic not rejected', (tester) async {
+        final maxTopicLength = maxTopicLengthVariants.currentValue!;
         await prepareWithTopic(tester,
-          makeStringWithCodePoints(kMaxTopicLengthCodePoints));
+          makeStringWithCodePoints(maxTopicLength), maxTopicLength);
         await tapSendButton(tester);
         checkNoErrorDialog(tester);
-      });
+      }, variant: maxTopicLengthVariants);
 
       testWidgets('code points not counted unnecessarily', (tester) async {
-        await prepareWithTopic(tester, 'a' * kMaxTopicLengthCodePoints);
+        final maxTopicLength = maxTopicLengthVariants.currentValue!;
+        await prepareWithTopic(tester, 'a' * maxTopicLength, maxTopicLength);
         check((controller as StreamComposeBoxController)
           .topic.debugLengthUnicodeCodePointsIfLong).isNull();
-      });
+      }, variant: maxTopicLengthVariants);
     });
   });