diff --git a/app/assets/javascripts/discourse-i18n/src/index.js b/app/assets/javascripts/discourse-i18n/src/index.js
index 236f0e1e91f..eafece820b8 100644
--- a/app/assets/javascripts/discourse-i18n/src/index.js
+++ b/app/assets/javascripts/discourse-i18n/src/index.js
@@ -33,6 +33,10 @@ export class I18n {
     return this.locale || this.defaultLocale;
   }
 
+  get currentBcp47Locale() {
+    return this.currentLocale().replace("_", "-");
+  }
+
   get pluralizationNormalizedLocale() {
     if (this.currentLocale() === "pt") {
       return "pt_PT";
diff --git a/app/assets/javascripts/discourse/app/components/topic-map/topic-views-chart.gjs b/app/assets/javascripts/discourse/app/components/topic-map/topic-views-chart.gjs
index 1940de73768..e8f188438dd 100644
--- a/app/assets/javascripts/discourse/app/components/topic-map/topic-views-chart.gjs
+++ b/app/assets/javascripts/discourse/app/components/topic-map/topic-views-chart.gjs
@@ -161,7 +161,7 @@ export default class TopicViewsChart extends Component {
               maxTicksLimit: 15,
               callback: function (value) {
                 const date = new Date(value + oneDay);
-                return date.toLocaleDateString(undefined, {
+                return date.toLocaleDateString(I18n.currentBcp47Locale, {
                   month: "2-digit",
                   day: "2-digit",
                 });
@@ -189,7 +189,7 @@ export default class TopicViewsChart extends Component {
                   const today = new Date();
                   date = today.getUTCDate();
                 }
-                return date.toLocaleDateString(undefined, {
+                return date.toLocaleDateString(I18n.currentBcp47Locale, {
                   month: "2-digit",
                   day: "2-digit",
                   year: "numeric",
diff --git a/app/assets/javascripts/discourse/app/components/topic-map/topic-views.gjs b/app/assets/javascripts/discourse/app/components/topic-map/topic-views.gjs
index c8c04493d17..254a9135964 100644
--- a/app/assets/javascripts/discourse/app/components/topic-map/topic-views.gjs
+++ b/app/assets/javascripts/discourse/app/components/topic-map/topic-views.gjs
@@ -1,4 +1,5 @@
 import Component from "@glimmer/component";
+import I18n from "I18n";
 
 export default class TopicViews extends Component {
   adjustAggregatedData(stats) {
@@ -6,11 +7,14 @@ export default class TopicViews extends Component {
 
     stats.forEach((stat) => {
       const localDate = new Date(`${stat.viewed_at}T00:00:00Z`);
-      const localDateStr = localDate.toLocaleDateString(undefined, {
-        year: "numeric",
-        month: "2-digit",
-        day: "2-digit",
-      });
+      const localDateStr = localDate.toLocaleDateString(
+        I18n.currentBcp47Locale,
+        {
+          year: "numeric",
+          month: "2-digit",
+          day: "2-digit",
+        }
+      );
 
       const existingStat = adjustedStats.find(
         (s) => s.dateStr === localDateStr
@@ -34,7 +38,7 @@ export default class TopicViews extends Component {
   }
 
   formatDate(date) {
-    return date.toLocaleDateString(undefined, {
+    return date.toLocaleDateString(I18n.currentBcp47Locale, {
       month: "2-digit",
       day: "2-digit",
     });
diff --git a/app/assets/javascripts/discourse/tests/unit/lib/i18n-test.js b/app/assets/javascripts/discourse/tests/unit/lib/i18n-test.js
index 4ec3a448b34..9f068bef4fe 100644
--- a/app/assets/javascripts/discourse/tests/unit/lib/i18n-test.js
+++ b/app/assets/javascripts/discourse/tests/unit/lib/i18n-test.js
@@ -373,4 +373,22 @@ module("Unit | Utility | i18n", function (hooks) {
       "Degrades gracefully if MF definitions are not available."
     );
   });
+
+  test("currentBcp47Locale", function (assert) {
+    Object.entries({
+      pt_BR: "pt-BR",
+      en_GB: "en-GB",
+      bs_BA: "bs-BA",
+      en: "en",
+      it: "it",
+      es: "es",
+    }).forEach(([input, output]) => {
+      I18n.locale = input;
+      assert.strictEqual(
+        I18n.currentBcp47Locale,
+        output,
+        `returns '${output}' for '${input}'`
+      );
+    });
+  });
 });