diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5718d89f..2cb0f2b5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ upstream release: 1.0.8). Format follows [Keep a Changelog](https://keepachangel
 ## [2.1.0] — Unreleased
 
 ### Added
+- **Monthly cost in the status bar** — the `statusBarMetric` setting gains a
+  new `monthly-cost` option. When selected, the first status-bar item shows the
+  current calendar month's total cost ($(calendar) icon) instead of today's
+  cost. Hover tooltip mirrors the today tooltip with month-to-date token and
+  cost breakdown.
 - **Weekly Opus limit in the status bar** — opt-in `showOpusWeekly` (default
   off) appends `opus:NN%` after the 5h / weekly quota figures, for heavy Opus
   users who want an at-a-glance weekly Opus signal. Merged from
diff --git a/src/extension.ts b/src/extension.ts
index d2e0fb1f..7adad76d 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -386,7 +386,7 @@ export class ClaudeCodeUsageExtension {
       showCost: s.get<boolean>('showCost'),
       showContext: s.get<boolean>('showContext'),
       contextWindowOverride: s.get<number>('contextWindowOverride'),
-      statusBarMetric: s.get<'cost' | 'tokens'>('statusBarMetric'),
+      statusBarMetric: s.get<'cost' | 'monthly-cost' | 'tokens'>('statusBarMetric'),
       showOpusWeekly: s.get<boolean>('showOpusWeekly'),
       usageLimitTracking: s.get<boolean>('usageLimitTracking'),
       adviceApiKey: s.get<string>('advice.apiKey'),
@@ -707,7 +707,7 @@ export class ClaudeCodeUsageExtension {
 
       // Update UI. Quota is pushed asynchronously by the fire-and-forget fetch
       // above; passing undefined leaves the quota item untouched here.
-      this.statusBar.updateUsageData(todayData, workspaceTodayData, undefined, undefined);
+      this.statusBar.updateUsageData(todayData, workspaceTodayData, undefined, undefined, monthData);
       this.statusBar.updateContext(
         ClaudeDataLoader.getCurrentContextInfo(records, workspacePath, config.contextWindowOverride)
       );
diff --git a/src/settings.ts b/src/settings.ts
index c87a242d..eeec5882 100644
--- a/src/settings.ts
+++ b/src/settings.ts
@@ -108,8 +108,9 @@ export const SETTINGS: SettingDef[] = [
     storage: 'state',
     group: 'statusBar',
     label: 'Status-bar metric',
-    help: "What the first status-bar item shows: today's cost, or today's total token count (k/M).",
-    enumValues: ['cost', 'tokens'],
+    help: "What the first status-bar item shows: today's cost, this month's cost, or today's total token count (k/M).",
+    enumValues: ['cost', 'monthly-cost', 'tokens'],
+    enumLabels: ["Today's cost", "Monthly cost", 'Token count'],
   },
   {
     key: 'showContext',
diff --git a/src/statusBar.ts b/src/statusBar.ts
index a69449c1..9300e9b9 100644
--- a/src/statusBar.ts
+++ b/src/statusBar.ts
@@ -11,8 +11,8 @@ export class StatusBarManager {
   private showCost: boolean = true;
   private showContext: boolean = true;
   private usageLimitTracking: boolean = true;
-  // First item shows today's cost ('cost') or today's total token count ('tokens').
-  private metric: 'cost' | 'tokens' = 'cost';
+  // First item shows today's cost ('cost'), this month's cost ('monthly-cost'), or today's token count ('tokens').
+  private metric: 'cost' | 'monthly-cost' | 'tokens' = 'cost';
   // Opt-in: append the weekly Opus limit (opus:NN%) to the quota item (PR #38,
   // @wheelbarrel00).
   private showOpusWeekly: boolean = false;
@@ -49,7 +49,7 @@ export class StatusBarManager {
     showCost: boolean,
     showContext: boolean,
     usageLimitTracking: boolean = true,
-    metric: 'cost' | 'tokens' = 'cost',
+    metric: 'cost' | 'monthly-cost' | 'tokens' = 'cost',
     showOpusWeekly: boolean = false
   ): void {
     this.showCost = showCost;
@@ -90,7 +90,8 @@ export class StatusBarManager {
     todayData: UsageData | null,
     workspaceTodayData?: UsageData | null,
     error?: string,
-    usageLimits?: ClaudeApiUsageResponse | null
+    usageLimits?: ClaudeApiUsageResponse | null,
+    monthData?: UsageData | null
   ): void {
     // Quota is account-level and decoupled from local-data state: the caller
     // is expected to call updateQuota() separately so workspaces without
@@ -107,7 +108,7 @@ export class StatusBarManager {
       return;
     }
 
-    this.showTodayData(todayData, workspaceTodayData ?? null);
+    this.showTodayData(todayData, workspaceTodayData ?? null, monthData ?? null);
     // The usageLimits arg is kept for callers that want a single-call update
     // path; quota was already refreshed earlier in this cycle.
     if (usageLimits !== undefined) {
@@ -124,10 +125,10 @@ export class StatusBarManager {
     }
   }
 
-  private showTodayData(todayData: UsageData, workspaceTodayData: UsageData | null): void {
+  private showTodayData(todayData: UsageData, workspaceTodayData: UsageData | null, monthData: UsageData | null): void {
     // Primary figure = today across all projects; secondary = today for the
     // current workspace, so you can see this project's share next to the global
-    // total. Both reset at midnight. The metric setting switches cost ↔ tokens.
+    // total. Both reset at midnight. The metric setting switches cost ↔ tokens ↔ monthly cost.
     const ws = workspaceTodayData ?? null;
     const totalTokens = (d: UsageData): number =>
       d.totalInputTokens + d.totalOutputTokens + d.totalCacheCreationTokens + d.totalCacheReadTokens;
@@ -137,6 +138,8 @@ export class StatusBarManager {
       if (ws) {
         text += ` $(folder) ${I18n.formatTokensCompact(totalTokens(ws))}`;
       }
+    } else if (this.metric === 'monthly-cost') {
+      text = `$(calendar) ${I18n.formatCurrency(monthData?.totalCost ?? 0)}`;
     } else {
       text = `$(pulse) ${I18n.formatCurrency(todayData.totalCost)}`;
       // Show the workspace figure whenever a workspace is open — including
@@ -147,7 +150,9 @@ export class StatusBarManager {
     }
     this.statusBarItem.text = text;
 
-    this.statusBarItem.tooltip = this.createTooltip(todayData, ws);
+    this.statusBarItem.tooltip = this.metric === 'monthly-cost'
+      ? this.createMonthlyTooltip(monthData)
+      : this.createTooltip(todayData, ws);
     this.statusBarItem.backgroundColor = undefined;
     this.applyCostVisibility();
   }
@@ -377,6 +382,23 @@ export class StatusBarManager {
     return md;
   }
 
+  private createMonthlyTooltip(monthData: UsageData | null): vscode.MarkdownString {
+    const t = I18n.t.popup;
+    const md = new vscode.MarkdownString();
+    md.supportThemeIcons = true;
+
+    md.appendMarkdown(`| | $(calendar) ${t.thisMonth} |\n`);
+    md.appendMarkdown(`|:--|--:|\n`);
+    md.appendMarkdown(`| ${t.cost} | ${I18n.formatCurrency(monthData?.totalCost ?? 0)} |\n`);
+    md.appendMarkdown(`| ${t.inputTokens} | ${I18n.formatNumber(monthData?.totalInputTokens ?? 0)} |\n`);
+    md.appendMarkdown(`| ${t.outputTokens} | ${I18n.formatNumber(monthData?.totalOutputTokens ?? 0)} |\n`);
+    md.appendMarkdown(`| ${t.cacheCreation} | ${I18n.formatNumber(monthData?.totalCacheCreationTokens ?? 0)} |\n`);
+    md.appendMarkdown(`| ${t.cacheRead} | ${I18n.formatNumber(monthData?.totalCacheReadTokens ?? 0)} |\n`);
+    md.appendMarkdown(`| ${t.messages} | ${I18n.formatNumber(monthData?.messageCount ?? 0)} |\n`);
+    md.appendMarkdown(`\n\n*Click for detailed breakdown*`);
+    return md;
+  }
+
   private createQuotaTooltip(usageLimits: ClaudeApiUsageResponse): vscode.MarkdownString {
     const t = I18n.t.popup;
     const md = new vscode.MarkdownString();
diff --git a/src/types.ts b/src/types.ts
index c3883760..46f2fb1e 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -230,8 +230,8 @@ export interface ExtensionConfig {
   showContext: boolean;
   // Manual context-window size override in tokens (0 = auto-detect).
   contextWindowOverride: number;
-  // First status-bar item: today's cost, or today's total token count.
-  statusBarMetric: 'cost' | 'tokens';
+  // First status-bar item: today's cost, this month's cost, or today's total token count.
+  statusBarMetric: 'cost' | 'monthly-cost' | 'tokens';
   // Opt-in: append the weekly Opus limit (opus:NN%) to the quota item (PR #38).
   showOpusWeekly: boolean;
   // Fetch real 5-hour / weekly limit utilisation via Claude Code's OAuth session.