diff --git a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/AutoRouterBenchmarksTab.test.tsx b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/AutoRouterBenchmarksTab.test.tsx
index 8d628a264f20..9cc4333b1e81 100644
--- a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/AutoRouterBenchmarksTab.test.tsx
+++ b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/AutoRouterBenchmarksTab.test.tsx
@@ -9,6 +9,16 @@ import { ApiError } from "@/lib/http/client";
 vi.mock("./useAutoRouterBenchmarks", () => ({ useAutoRouterBenchmarks: vi.fn() }));
 vi.mock("@/app/(dashboard)/hooks/models/useModels", () => ({ useAutoRouters: vi.fn() }));
 vi.mock("./ShadowEvalSection", () => ({ default: () => <div data-testid="shadow-eval-section" /> }));
+vi.mock("@/components/shared/advanced_date_picker", () => ({
+  __esModule: true,
+  default: ({ onValueChange }: { onValueChange: (value: { from?: Date; to?: Date }) => void }) => (
+    <button
+      type="button"
+      data-testid="date-picker"
+      onClick={() => onValueChange({ from: new Date(2026, 7, 1), to: new Date(2026, 7, 5) })}
+    />
+  ),
+}));
 
 import { useAutoRouters } from "@/app/(dashboard)/hooks/models/useModels";
 
@@ -112,12 +122,28 @@ const response = (groups: AutoRouterBenchmarkGroup[], shared: Totals = totals())
 });
 
 const renderTab = () => {
+  const dateValue = { from: new Date(2026, 6, 6), to: new Date(2026, 7, 5) };
+  const onDateChange = vi.fn();
+  const activity = {
+    dateValue,
+    onDateChange,
+    results: [],
+    loading: false,
+    isFetchingMore: false,
+    progress: { currentPage: 1, totalPages: 1 },
+    cancelled: false,
+    cancel: vi.fn(),
+  };
   const queryClient = new QueryClient({ defaultOptions: { queries: { retry: false } } });
-  return render(
-    <QueryClientProvider client={queryClient}>
-      <AutoRouterBenchmarksTab accessToken="sk-test" />
-    </QueryClientProvider>,
-  );
+  return {
+    dateValue,
+    onDateChange,
+    ...render(
+      <QueryClientProvider client={queryClient}>
+        <AutoRouterBenchmarksTab accessToken="sk-test" activity={activity} />
+      </QueryClientProvider>,
+    ),
+  };
 };
 
 describe("AutoRouterBenchmarksTab", () => {
@@ -304,20 +330,15 @@ describe("AutoRouterBenchmarksTab", () => {
     expect(screen.queryByText("-0%")).not.toBeInTheDocument();
   });
 
-  it("requests the default thirty day window and widens or narrows it from the picker", () => {
+  it("queries the shared picker's range and pushes picker changes back to the shared state", () => {
     mockHook({ data: response([group()]) });
-    renderTab();
-
-    expect(vi.mocked(useAutoRouterBenchmarks)).toHaveBeenCalledWith("sk-test", "30d");
-    expect(screen.getByText("Last 30 days")).toBeInTheDocument();
+    const { dateValue, onDateChange } = renderTab();
 
-    fireEvent.click(screen.getByRole("tab", { name: "7d" }));
-    expect(vi.mocked(useAutoRouterBenchmarks)).toHaveBeenCalledWith("sk-test", "7d");
-    expect(screen.getByText("Last 7 days")).toBeInTheDocument();
+    expect(vi.mocked(useAutoRouterBenchmarks)).toHaveBeenCalledWith("sk-test", dateValue);
+    expect(screen.getByText("Jul 6 – Aug 5 (UTC)")).toBeInTheDocument();
 
-    fireEvent.click(screen.getByRole("tab", { name: "24h" }));
-    expect(vi.mocked(useAutoRouterBenchmarks)).toHaveBeenCalledWith("sk-test", "24h");
-    expect(screen.getByText("Last 24 hours")).toBeInTheDocument();
+    fireEvent.click(screen.getByTestId("date-picker"));
+    expect(onDateChange).toHaveBeenCalledWith({ from: new Date(2026, 7, 1), to: new Date(2026, 7, 5) });
   });
 
   it("shows usage by default and mounts shadow evals only when its sub-tab is selected", () => {
@@ -347,11 +368,11 @@ describe("AutoRouterBenchmarksTab", () => {
     expect(screen.getByTestId("shadow-eval-section")).toBeInTheDocument();
   });
 
-  it("keeps the window picker reachable while a window has no sessions", () => {
+  it("keeps the range picker reachable while a window has no sessions", () => {
     mockHook({ data: response([], zeroTotals) });
     renderTab();
 
-    expect(screen.getByRole("tab", { name: "30d" })).toBeInTheDocument();
+    expect(screen.getByTestId("date-picker")).toBeInTheDocument();
     expect(screen.getByText("All auto-routers")).toBeInTheDocument();
   });
 });
diff --git a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/AutoRouterBenchmarksTab.tsx b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/AutoRouterBenchmarksTab.tsx
index d92696cb68a0..fda1c1b11558 100644
--- a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/AutoRouterBenchmarksTab.tsx
+++ b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/AutoRouterBenchmarksTab.tsx
@@ -4,6 +4,7 @@ import React, { useState } from "react";
 
 import type { AutoRouterDeployment } from "@/app/(dashboard)/hooks/models/useModels";
 import { useAutoRouters } from "@/app/(dashboard)/hooks/models/useModels";
+import AdvancedDatePicker from "@/components/shared/advanced_date_picker";
 import { Badge } from "@/components/ui/badge";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
@@ -15,7 +16,6 @@ import { formatNumberWithCommas } from "@/utils/dataUtils";
 
 import {
   ALL_ROUTERS,
-  WINDOW_LABELS,
   bucketRows,
   bucketTurnsTotal,
   durationLabel,
@@ -27,13 +27,13 @@ import {
   type AutoRouterBenchmarksResponse,
   type AutoRouterCacheStats,
   type BenchmarkView,
-  type BenchmarkWindow,
   type BucketRow,
 } from "./autoRouterBenchmarks";
-import { usd } from "./costOptimizationUtils";
+import { formatRangeLabel, usd } from "./costOptimizationUtils";
 import ShadowEvalSection from "./ShadowEvalSection";
 import TierTurnsChart from "./TierTurnsChart";
 import { useAutoRouterBenchmarks } from "./useAutoRouterBenchmarks";
+import { DailyActivityRange } from "./useDailyActivityRange";
 
 const Message: React.FC<{ children: React.ReactNode }> = ({ children }) => (
   <p className="py-8 text-center text-sm text-muted-foreground">{children}</p>
@@ -248,7 +248,8 @@ const BenchmarksBody: React.FC<BenchmarksBodyProps> = ({ isPending, error, data,
       <p className="text-xs text-muted-foreground">
         Compares your actual routed spend with the estimated cost of using only the most expensive model configured in
         the auto-router. It accounts for both the cache savings from staying on one model and the added cache costs from
-        switching models.
+        switching models. The range counts whole sessions that overlap it, so totals can differ slightly from the
+        Overall tab, which buckets savings by UTC day.
       </p>
 
       <div className="space-y-4">
@@ -266,32 +267,28 @@ const BenchmarksBody: React.FC<BenchmarksBodyProps> = ({ isPending, error, data,
 
 interface AutoRouterBenchmarksTabProps {
   accessToken: string | null;
+  activity: DailyActivityRange;
 }
 
-const UsageView: React.FC<AutoRouterBenchmarksTabProps> = ({ accessToken }) => {
-  const [range, setRange] = useState<BenchmarkWindow>("30d");
-  const { data, isPending, error } = useAutoRouterBenchmarks(accessToken, range);
+const UsageView: React.FC<AutoRouterBenchmarksTabProps> = ({ accessToken, activity }) => {
+  const { dateValue, onDateChange } = activity;
+  const { data, isPending, error } = useAutoRouterBenchmarks(accessToken, dateValue);
   const [selectedKey, setSelectedKey] = useState<string>(ALL_ROUTERS);
   const { data: autoRouters } = useAutoRouters();
 
   const groups = data?.groups ?? [];
   const selectedLabel = data ? viewFor(data, selectedKey).label : "All auto-routers";
+  const rangeLabel = formatRangeLabel(dateValue.from, dateValue.to);
 
   return (
     <div className="w-full space-y-6">
       <div className="flex flex-col gap-3 sm:flex-row sm:items-start sm:justify-between">
         <div>
           <h2 className="text-xl font-semibold text-foreground">Auto-router usage</h2>
-          <p className="mt-1 text-sm text-muted-foreground">{WINDOW_LABELS[range]}</p>
+          {rangeLabel && <p className="mt-1 text-sm text-muted-foreground">{rangeLabel} (UTC)</p>}
         </div>
         <div className="flex w-full flex-col gap-3 sm:w-auto sm:flex-row sm:items-center">
-          <Tabs value={range} onValueChange={(value) => setRange(value === "7d" || value === "24h" ? value : "30d")}>
-            <TabsList>
-              <TabsTrigger value="30d">30d</TabsTrigger>
-              <TabsTrigger value="7d">7d</TabsTrigger>
-              <TabsTrigger value="24h">24h</TabsTrigger>
-            </TabsList>
-          </Tabs>
+          <AdvancedDatePicker value={dateValue} onValueChange={onDateChange} />
           <div className="w-full sm:w-64">
             <Select value={selectedKey} onValueChange={(value: string | null) => setSelectedKey(value ?? ALL_ROUTERS)}>
               <SelectTrigger className="w-full">
@@ -321,7 +318,7 @@ const UsageView: React.FC<AutoRouterBenchmarksTabProps> = ({ accessToken }) => {
   );
 };
 
-const AutoRouterBenchmarksTab: React.FC<AutoRouterBenchmarksTabProps> = ({ accessToken }) => {
+const AutoRouterBenchmarksTab: React.FC<AutoRouterBenchmarksTabProps> = ({ accessToken, activity }) => {
   const [visitedTabs, setVisitedTabs] = useState<readonly string[]>(["usage"]);
 
   const handleTabChange = (value: unknown) => {
@@ -344,7 +341,7 @@ const AutoRouterBenchmarksTab: React.FC<AutoRouterBenchmarksTabProps> = ({ acces
       </TabsList>
 
       <TabsContent value="usage" keepMounted={visitedTabs.includes("usage")}>
-        <UsageView accessToken={accessToken} />
+        <UsageView accessToken={accessToken} activity={activity} />
       </TabsContent>
       <TabsContent value="shadow-evals" keepMounted={visitedTabs.includes("shadow-evals")}>
         <ShadowEvalSection />
diff --git a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/CostOptimizationView.tsx b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/CostOptimizationView.tsx
index a588b28ecea5..165c63ea969a 100644
--- a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/CostOptimizationView.tsx
+++ b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/CostOptimizationView.tsx
@@ -101,7 +101,7 @@ const CostOptimizationView: React.FC<CostOptimizationViewProps> = ({ accessToken
               <PromptCachingTab accessToken={accessToken} activity={activity} />
             </TabsContent>
             <TabsContent value="autorouter-usage" keepMounted={visitedTabs.includes("autorouter-usage")}>
-              <AutoRouterBenchmarksTab accessToken={accessToken} />
+              <AutoRouterBenchmarksTab accessToken={accessToken} activity={activity} />
             </TabsContent>
           </>
         )}
diff --git a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/autoRouterBenchmarks.test.ts b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/autoRouterBenchmarks.test.ts
index 57c059b5524d..9a70fd9289aa 100644
--- a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/autoRouterBenchmarks.test.ts
+++ b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/autoRouterBenchmarks.test.ts
@@ -10,7 +10,6 @@ import {
   groupLabel,
   pctLabel,
   viewFor,
-  windowFor,
   type AutoRouterBenchmarkGroup,
   type AutoRouterBenchmarksResponse,
   type AutoRouterCacheStats,
@@ -153,21 +152,6 @@ describe("expiredMissShare", () => {
   });
 });
 
-describe("windowFor", () => {
-  const noon = new Date("2026-08-05T12:00:00Z");
-
-  it("derives each picker range as UTC calendar days ending today", () => {
-    expect(windowFor("30d", noon)).toEqual({ start_date: "2026-07-06", end_date: "2026-08-05" });
-    expect(windowFor("7d", noon)).toEqual({ start_date: "2026-07-29", end_date: "2026-08-05" });
-    expect(windowFor("24h", noon)).toEqual({ start_date: "2026-08-04", end_date: "2026-08-05" });
-  });
-
-  it("uses UTC days, not the local calendar", () => {
-    const lateEvening = new Date("2026-08-05T23:30:00-05:00");
-    expect(windowFor("24h", lateEvening)).toEqual({ start_date: "2026-08-05", end_date: "2026-08-06" });
-  });
-});
-
 describe("formatting", () => {
   it("renders session length in the largest sensible unit", () => {
     expect(durationLabel(42)).toBe("42s");
diff --git a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/autoRouterBenchmarks.ts b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/autoRouterBenchmarks.ts
index 2e1031ce7011..997df41e963b 100644
--- a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/autoRouterBenchmarks.ts
+++ b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/autoRouterBenchmarks.ts
@@ -7,21 +7,6 @@ export type AutoRouterCacheStats = components["schemas"]["AutoRouterCacheStats"]
 
 export const ALL_ROUTERS = "__all__";
 
-export type BenchmarkWindow = "30d" | "7d" | "24h";
-
-const WINDOW_DAYS: Record<BenchmarkWindow, number> = { "30d": 30, "7d": 7, "24h": 1 };
-
-export const WINDOW_LABELS: Record<BenchmarkWindow, string> = {
-  "30d": "Last 30 days",
-  "7d": "Last 7 days",
-  "24h": "Last 24 hours",
-};
-
-export const windowFor = (range: BenchmarkWindow, now: Date): { start_date: string; end_date: string } => ({
-  start_date: new Date(now.getTime() - WINDOW_DAYS[range] * 24 * 60 * 60 * 1000).toISOString().slice(0, 10),
-  end_date: now.toISOString().slice(0, 10),
-});
-
 export interface BenchmarkView {
   label: string;
   stats: AutoRouterBenchmarkTotals | AutoRouterBenchmarkGroup;
diff --git a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/useAutoRouterBenchmarks.test.ts b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/useAutoRouterBenchmarks.test.ts
new file mode 100644
index 000000000000..e8a858ef3a57
--- /dev/null
+++ b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/useAutoRouterBenchmarks.test.ts
@@ -0,0 +1,46 @@
+import { describe, expect, it, vi } from "vitest";
+
+vi.mock("@/components/networking", () => ({ formatDate: vi.fn() }));
+vi.mock("@/lib/http/api", () => ({ $api: { useQuery: vi.fn() } }));
+
+import { benchmarksWindow } from "./useAutoRouterBenchmarks";
+
+const localDay =
+  (offsetHours: number) =>
+  (d: Date): string =>
+    new Date(d.getTime() + offsetHours * 3_600_000).toISOString().slice(0, 10);
+
+const pacific = localDay(-7);
+const tokyo = localDay(+9);
+
+describe("benchmarksWindow", () => {
+  it("passes a historical range through as the picked local calendar days", () => {
+    const now = new Date("2026-08-21T19:00:00Z");
+    const range = { from: new Date("2026-07-06T19:00:00Z"), to: new Date("2026-08-05T19:00:00Z") };
+    expect(benchmarksWindow(range, now, pacific)).toEqual({ start_date: "2026-07-06", end_date: "2026-08-05" });
+  });
+
+  it("keeps a range ending today unchanged while the local and UTC days still agree", () => {
+    const now = new Date("2026-08-21T19:00:00Z");
+    const range = { from: new Date("2026-07-22T19:00:00Z"), to: now };
+    expect(benchmarksWindow(range, now, pacific)).toEqual({ start_date: "2026-07-22", end_date: "2026-08-21" });
+  });
+
+  it("extends a range ending today to the current UTC day once UTC rolls past local midnight", () => {
+    const now = new Date("2026-08-22T03:00:00Z");
+    const range = { from: new Date("2026-07-22T19:00:00Z"), to: now };
+    expect(benchmarksWindow(range, now, pacific)).toEqual({ start_date: "2026-07-22", end_date: "2026-08-22" });
+  });
+
+  it("never shrinks a range for a caller east of UTC whose local day is already tomorrow", () => {
+    const now = new Date("2026-08-21T19:00:00Z");
+    const range = { from: new Date("2026-07-22T19:00:00Z"), to: now };
+    expect(benchmarksWindow(range, now, tokyo)).toEqual({ start_date: "2026-07-23", end_date: "2026-08-22" });
+  });
+
+  it("sends no dates while the picker is missing either end", () => {
+    const now = new Date("2026-08-21T19:00:00Z");
+    expect(benchmarksWindow({ from: now }, now, pacific)).toEqual({});
+    expect(benchmarksWindow({ to: now }, now, pacific)).toEqual({});
+  });
+});
diff --git a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/useAutoRouterBenchmarks.ts b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/useAutoRouterBenchmarks.ts
index ab87c5ef4307..155c9d0c696d 100644
--- a/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/useAutoRouterBenchmarks.ts
+++ b/ui/litellm-dashboard/src/app/(dashboard)/cost-optimization/_components/useAutoRouterBenchmarks.ts
@@ -1,11 +1,32 @@
+import { formatDate } from "@/components/networking";
 import { $api } from "@/lib/http/api";
 
-import { windowFor, type BenchmarkWindow } from "./autoRouterBenchmarks";
+import type { DateRange } from "./useDailyActivityRange";
 
-export const useAutoRouterBenchmarks = (accessToken: string | null, range: BenchmarkWindow) =>
+/**
+ * The endpoint cuts on UTC days but the picker hands back local dates, so west of UTC a
+ * range ending today would hide sessions started after UTC midnight. Extend it to the
+ * current UTC day (only the empty future is added), mirroring include_current_utc_day.
+ */
+export const benchmarksWindow = (
+  range: DateRange,
+  now: Date,
+  toLocalDay: (d: Date) => string = formatDate,
+): { start_date: string; end_date: string } | Record<string, never> => {
+  if (!range.from || !range.to) return {};
+  const end_date = toLocalDay(range.to);
+  const utcToday = now.toISOString().slice(0, 10);
+  const endsToday = end_date >= toLocalDay(now);
+  return {
+    start_date: toLocalDay(range.from),
+    end_date: endsToday && utcToday > end_date ? utcToday : end_date,
+  };
+};
+
+export const useAutoRouterBenchmarks = (accessToken: string | null, range: DateRange) =>
   $api.useQuery(
     "get",
     "/auto_router/benchmarks",
-    { params: { query: windowFor(range, new Date()) } },
-    { enabled: Boolean(accessToken), retry: false },
+    { params: { query: benchmarksWindow(range, new Date()) } },
+    { enabled: Boolean(accessToken && range.from && range.to), retry: false },
   );