diff --git a/src/components/insights/mood/mood-better-days.tsx b/src/components/insights/mood/mood-better-days.tsx
index 07b507214..55738c513 100644
--- a/src/components/insights/mood/mood-better-days.tsx
+++ b/src/components/insights/mood/mood-better-days.tsx
@@ -2,7 +2,7 @@
 
 import { ArrowDownRight, ArrowUpRight } from "lucide-react";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 import { moodTagIcon } from "@/components/mood/mood-tag-icons";
 import { cn } from "@/lib/utils";
 import type { MoodInfluenceConfidence } from "./mood-tag-influence";
@@ -70,6 +70,7 @@ export function MoodBetterDays({
   factors: MoodBetterDayFactor[];
 }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   if (factors.length === 0) return null;
 
   return (
@@ -108,9 +109,9 @@ export function MoodBetterDays({
           // metric factors show the correlation coefficient.
           const effectText =
             factor.source === "tag" && factor.delta != null
-              ? `${factor.delta >= 0 ? "+" : ""}${factor.delta.toFixed(1)}`
+              ? `${factor.delta >= 0 ? "+" : ""}${nf.number(factor.delta, 1)}`
               : factor.r != null
-                ? `r ${factor.r.toFixed(2)}`
+                ? `r ${nf.number(factor.r, 2)}`
                 : "";
 
           return (
diff --git a/src/components/insights/mood/mood-context-comparison.tsx b/src/components/insights/mood/mood-context-comparison.tsx
index 3df6ff9ba..4bcf8a63e 100644
--- a/src/components/insights/mood/mood-context-comparison.tsx
+++ b/src/components/insights/mood/mood-context-comparison.tsx
@@ -16,7 +16,7 @@
  * them; a second threshold in the presentation layer would be a second place
  * to get the statistics wrong.
  */
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 import { contextValueLabelKey } from "@/lib/mood/context-vocabulary";
 import type { ContextComparisonRow } from "@/lib/insights/mood-context-crosstab";
 
@@ -26,6 +26,7 @@ export function MoodContextComparison({
   rows: ContextComparisonRow[];
 }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   if (rows.length === 0) return null;
 
   return (
@@ -50,8 +51,8 @@ export function MoodContextComparison({
                 {t("insights.mood.contextComparison.statement", {
                   label,
                   direction,
-                  withAvg: row.withAvg.toFixed(1),
-                  withoutAvg: row.withoutAvg.toFixed(1),
+                  withAvg: nf.number(row.withAvg, 1),
+                  withoutAvg: nf.number(row.withoutAvg, 1),
                 })}
               </p>
               {/* The counts ride with the statement, in the same block a
diff --git a/src/components/insights/mood/mood-correlation-cards.tsx b/src/components/insights/mood/mood-correlation-cards.tsx
index 804bf52ff..36c07db54 100644
--- a/src/components/insights/mood/mood-correlation-cards.tsx
+++ b/src/components/insights/mood/mood-correlation-cards.tsx
@@ -8,7 +8,7 @@ import { Card, CardContent, CardHeader } from "@/components/ui/card";
 import { TileHeader } from "@/components/insights/tile-header";
 import { EmptyState } from "@/components/ui/empty-state";
 import { Skeleton } from "@/components/ui/skeleton";
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 import type { CorrelationResult } from "@/lib/analytics/correlations";
 import { MoodExplainerIcon } from "./mood-explainer-icon";
 
@@ -106,6 +106,7 @@ function MoodCorrelationCard({
   className?: string;
 }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   const hasResult = data.result != null;
 
   // Three different silences, and the reader deserves to know which one they
@@ -164,7 +165,7 @@ function MoodCorrelationCard({
                   label={t("insights.mood.correlation.sourceLabel")}
                   detail={t("insights.mood.correlation.source", {
                     n: data.n,
-                    r: data.result.r.toFixed(2),
+                    r: nf.number(data.result.r, 2),
                   })}
                 />
               </div>
@@ -179,7 +180,7 @@ function MoodCorrelationCard({
             label={t("insights.mood.correlation.sourceLabel")}
             detail={t("insights.mood.correlation.source", {
               n: data.n,
-              r: data.result.r.toFixed(2),
+              r: nf.number(data.result.r, 2),
             })}
           />
         ) : null}
diff --git a/src/components/insights/mood/mood-discovered-relations.tsx b/src/components/insights/mood/mood-discovered-relations.tsx
index 53bca5e81..4a9adf235 100644
--- a/src/components/insights/mood/mood-discovered-relations.tsx
+++ b/src/components/insights/mood/mood-discovered-relations.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 import { MoodExplainerIcon } from "./mood-explainer-icon";
 import {
   PatternDismissButton,
@@ -94,6 +94,7 @@ export function MoodDiscoveredRelations({
   pairsTested: number;
 }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   const dismissal = usePatternDismissalOverrides();
 
   if (pairs.length === 0) return null;
@@ -169,8 +170,8 @@ export function MoodDiscoveredRelations({
                   label={t("insights.mood.discovery.statLabel")}
                   detail={t("insights.mood.discovery.stat", {
                     n: pair.n,
-                    r: pair.r.toFixed(2),
-                    q: pair.qValue.toFixed(3),
+                    r: nf.number(pair.r, 2),
+                    q: nf.number(pair.qValue, 3),
                   })}
                 />
               </span>
diff --git a/src/components/insights/mood/mood-factor-metric-crosstab.tsx b/src/components/insights/mood/mood-factor-metric-crosstab.tsx
index 65d1b5a4e..6cd598af6 100644
--- a/src/components/insights/mood/mood-factor-metric-crosstab.tsx
+++ b/src/components/insights/mood/mood-factor-metric-crosstab.tsx
@@ -1,6 +1,7 @@
 "use client";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
+import type { Formatters } from "@/lib/format-locale";
 import { useUnitDisplay } from "@/hooks/use-unit-display";
 import { moodTagIcon } from "@/components/mood/mood-tag-icons";
 import { cn } from "@/lib/utils";
@@ -84,8 +85,12 @@ const CONFIDENCE_CLASS: Record<MoodInfluenceConfidence, string> = {
 };
 
 /** Whole numbers for steps; one decimal otherwise. */
-function fmt(value: number, display: MoodFactorCrosstabDisplay): string {
-  return display === "steps" ? Math.round(value).toString() : value.toFixed(1);
+function formatValue(
+  value: number,
+  display: MoodFactorCrosstabDisplay,
+  nf: Formatters,
+): string {
+  return display === "steps" ? nf.integer(value) : nf.number(value, 1);
 }
 
 export function MoodFactorMetricCrosstab({
@@ -94,6 +99,7 @@ export function MoodFactorMetricCrosstab({
   rows: MoodFactorMetricCrosstabRow[];
 }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   const unitDisplay = useUnitDisplay();
   const dismissal = usePatternDismissalOverrides();
   if (rows.length === 0) return null;
@@ -143,7 +149,7 @@ export function MoodFactorMetricCrosstab({
           // green/red would imply a health verdict the data doesn't support.
           // The sign prefix + `data-direction` carry the direction.
           const up = row.delta >= 0;
-          const deltaText = `${up ? "+" : ""}${fmt(conv(row.delta), row.display)} ${unit}`;
+          const deltaText = `${up ? "+" : ""}${formatValue(conv(row.delta), row.display, nf)} ${unit}`;
           return (
             <li
               key={`${row.metricKey}:${row.factor}`}
@@ -197,8 +203,8 @@ export function MoodFactorMetricCrosstab({
                   {
                     factor: factorLabel,
                     metric: metricLabel,
-                    lowAvg: fmt(conv(row.lowAvg), row.display),
-                    highAvg: fmt(conv(row.highAvg), row.display),
+                    lowAvg: formatValue(conv(row.lowAvg), row.display, nf),
+                    highAvg: formatValue(conv(row.highAvg), row.display, nf),
                     unit,
                     lowDays: row.lowDays,
                   },
diff --git a/src/components/insights/mood/mood-structured-tag-breakdown.tsx b/src/components/insights/mood/mood-structured-tag-breakdown.tsx
index 9753a140d..eab6a6b3f 100644
--- a/src/components/insights/mood/mood-structured-tag-breakdown.tsx
+++ b/src/components/insights/mood/mood-structured-tag-breakdown.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 import { moodTagIcon } from "@/components/mood/mood-tag-icons";
 
 /**
@@ -40,6 +40,7 @@ export function MoodStructuredTagBreakdown({
   tags: MoodStructuredTagRow[];
 }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   const maxCount = tags.reduce((m, row) => Math.max(m, row.count), 0) || 1;
 
   return (
@@ -74,7 +75,7 @@ export function MoodStructuredTagBreakdown({
               style={{ color: colorForScore(row.avgScore) }}
               title={t("insights.mood.tagAvgMood")}
             >
-              {row.avgScore.toFixed(1)}
+              {nf.number(row.avgScore, 1)}
             </span>
           </li>
         );
diff --git a/src/components/insights/mood/mood-tag-breakdown.tsx b/src/components/insights/mood/mood-tag-breakdown.tsx
index 2e4c3d5bc..53e63793e 100644
--- a/src/components/insights/mood/mood-tag-breakdown.tsx
+++ b/src/components/insights/mood/mood-tag-breakdown.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 
 /**
  * v1.8.5 — tag / trigger breakdown.
@@ -30,6 +30,7 @@ function colorForScore(score: number): string {
 
 export function MoodTagBreakdown({ tags }: { tags: MoodTagRow[] }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   const maxCount = tags.reduce((m, row) => Math.max(m, row.count), 0) || 1;
 
   return (
@@ -61,7 +62,7 @@ export function MoodTagBreakdown({ tags }: { tags: MoodTagRow[] }) {
             style={{ color: colorForScore(row.avgScore) }}
             title={t("insights.mood.tagAvgMood")}
           >
-            {row.avgScore.toFixed(1)}
+            {nf.number(row.avgScore, 1)}
           </span>
         </li>
       ))}
diff --git a/src/components/insights/mood/mood-tag-influence.tsx b/src/components/insights/mood/mood-tag-influence.tsx
index 619c2d699..4db56866a 100644
--- a/src/components/insights/mood/mood-tag-influence.tsx
+++ b/src/components/insights/mood/mood-tag-influence.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 import { moodTagIcon } from "@/components/mood/mood-tag-icons";
 import { cn } from "@/lib/utils";
 
@@ -62,6 +62,7 @@ function deltaColor(delta: number): string {
 
 export function MoodTagInfluence({ rows }: { rows: MoodTagInfluenceRow[] }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   if (rows.length === 0) return null;
 
   return (
@@ -71,7 +72,7 @@ export function MoodTagInfluence({ rows }: { rows: MoodTagInfluenceRow[] }) {
           const Icon = row.labelKey ? moodTagIcon(row.icon) : null;
           const label = row.label ?? (row.labelKey ? t(row.labelKey) : row.tag);
           const up = row.delta >= 0;
-          const deltaText = `${up ? "+" : ""}${row.delta.toFixed(1)}`;
+          const deltaText = `${up ? "+" : ""}${nf.number(row.delta, 1)}`;
           return (
             <li
               key={`${row.labelKey ?? "flat"}:${row.tag}`}
@@ -110,8 +111,8 @@ export function MoodTagInfluence({ rows }: { rows: MoodTagInfluenceRow[] }) {
               </div>
               <p className="text-muted-foreground text-xs">
                 {t("insights.mood.influence.detail", {
-                  withAvg: row.withAvg.toFixed(1),
-                  withoutAvg: row.withoutAvg.toFixed(1),
+                  withAvg: nf.number(row.withAvg, 1),
+                  withoutAvg: nf.number(row.withoutAvg, 1),
                   withDays: row.withDays,
                 })}
               </p>
diff --git a/src/components/insights/mood/mood-tag-metric-crosstab.tsx b/src/components/insights/mood/mood-tag-metric-crosstab.tsx
index 9263fbaee..60d926a38 100644
--- a/src/components/insights/mood/mood-tag-metric-crosstab.tsx
+++ b/src/components/insights/mood/mood-tag-metric-crosstab.tsx
@@ -1,6 +1,7 @@
 "use client";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
+import type { Formatters } from "@/lib/format-locale";
 import { moodTagIcon } from "@/components/mood/mood-tag-icons";
 import { cn } from "@/lib/utils";
 import type { MoodInfluenceConfidence } from "./mood-tag-influence";
@@ -92,8 +93,12 @@ const CONFIDENCE_CLASS: Record<MoodInfluenceConfidence, string> = {
 };
 
 /** One decimal for hours/score, whole numbers for kcal. */
-function fmt(value: number, display: MoodCrosstabDisplay): string {
-  return display === "kcal" ? Math.round(value).toString() : value.toFixed(1);
+function formatValue(
+  value: number,
+  display: MoodCrosstabDisplay,
+  nf: Formatters,
+): string {
+  return display === "kcal" ? nf.integer(value) : nf.number(value, 1);
 }
 
 export function MoodTagMetricCrosstab({
@@ -102,6 +107,7 @@ export function MoodTagMetricCrosstab({
   rows: MoodTagMetricCrosstabRow[];
 }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
   const dismissal = usePatternDismissalOverrides();
   if (rows.length === 0) return null;
 
@@ -135,7 +141,7 @@ export function MoodTagMetricCrosstab({
           );
           const unit = t(UNIT_KEY[row.display]);
           const up = row.delta >= 0;
-          const deltaText = `${up ? "+" : ""}${fmt(row.delta, row.display)} ${unit}`;
+          const deltaText = `${up ? "+" : ""}${formatValue(row.delta, row.display, nf)} ${unit}`;
           return (
             <li
               key={`${row.metricKey}:${row.tag}`}
@@ -187,8 +193,8 @@ export function MoodTagMetricCrosstab({
                     ? "insights.mood.crosstab.detailNextDay"
                     : "insights.mood.crosstab.detailSameDay",
                   {
-                    withAvg: fmt(row.withAvg, row.display),
-                    withoutAvg: fmt(row.withoutAvg, row.display),
+                    withAvg: formatValue(row.withAvg, row.display, nf),
+                    withoutAvg: formatValue(row.withoutAvg, row.display, nf),
                     unit,
                     withDays: row.withDays,
                   },
diff --git a/src/components/insights/mood/mood-time-of-day-chart.tsx b/src/components/insights/mood/mood-time-of-day-chart.tsx
index e1f96541a..0df704b99 100644
--- a/src/components/insights/mood/mood-time-of-day-chart.tsx
+++ b/src/components/insights/mood/mood-time-of-day-chart.tsx
@@ -11,7 +11,7 @@ import {
   YAxis,
 } from "recharts";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 
 /**
  * v1.9.0 — average mood per part of day.
@@ -62,6 +62,7 @@ export function MoodTimeOfDayChart({
   pattern: MoodTimeOfDayPattern;
 }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
 
   const data = pattern.buckets.map((row) => ({
     bucket: row.bucket,
@@ -125,7 +126,7 @@ export function MoodTimeOfDayChart({
                   return [t("insights.mood.weekdayNoData"), ""];
                 }
                 return [
-                  `${payload.avgScore.toFixed(1)} (${payload.count})`,
+                  `${nf.number(payload.avgScore, 1)} (${payload.count})`,
                   t("insights.mood.timeOfDay.title"),
                 ];
               }}
diff --git a/src/components/insights/mood/mood-weekday-chart.tsx b/src/components/insights/mood/mood-weekday-chart.tsx
index a0d69225f..ef53ee877 100644
--- a/src/components/insights/mood/mood-weekday-chart.tsx
+++ b/src/components/insights/mood/mood-weekday-chart.tsx
@@ -12,7 +12,7 @@ import {
   YAxis,
 } from "recharts";
 
-import { useTranslations } from "@/lib/i18n/context";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
 
 /**
  * v1.8.5 — average mood per weekday (Monday-aligned).
@@ -50,6 +50,7 @@ function colorForScore(score: number): string {
 
 export function MoodWeekdayChart({ weekday }: { weekday: MoodWeekdayRow[] }) {
   const { t } = useTranslations();
+  const nf = useFormatters();
 
   const data = weekday.map((row) => ({
     weekday: row.weekday,
@@ -134,7 +135,7 @@ export function MoodWeekdayChart({ weekday }: { weekday: MoodWeekdayRow[] }) {
                   return [t("insights.mood.weekdayNoData"), ""];
                 }
                 return [
-                  `${payload.avgScore.toFixed(1)} (${payload.count})`,
+                  `${nf.number(payload.avgScore, 1)} (${payload.count})`,
                   t("insights.mood.weekdayTitle"),
                 ];
               }}