diff --git a/web/src/components/ActivityCalendar/CalendarHeader.tsx b/web/src/components/ActivityCalendar/CalendarHeader.tsx
new file mode 100644
index 000000000..154adbbb8
--- /dev/null
+++ b/web/src/components/ActivityCalendar/CalendarHeader.tsx
@@ -0,0 +1,73 @@
+import { ChevronLeftIcon, ChevronRightIcon } from "lucide-react";
+import { useMemo } from "react";
+import { Button } from "@/components/ui/button";
+import { useTranslate } from "@/utils/i18n";
+
+interface CalendarHeaderProps {
+  selectedYear: number;
+  onYearChange: (year: number) => void;
+  canGoPrev: boolean;
+  canGoNext: boolean;
+}
+
+export const CalendarHeader = ({ selectedYear, onYearChange, canGoPrev, canGoNext }: CalendarHeaderProps) => {
+  const t = useTranslate();
+  const currentYear = useMemo(() => new Date().getFullYear(), []);
+  const isCurrentYear = selectedYear === currentYear;
+
+  const handlePrevYear = () => {
+    if (canGoPrev) {
+      onYearChange(selectedYear - 1);
+    }
+  };
+
+  const handleNextYear = () => {
+    if (canGoNext) {
+      onYearChange(selectedYear + 1);
+    }
+  };
+
+  const handleToday = () => {
+    onYearChange(currentYear);
+  };
+
+  return (
+    <div className="flex items-center justify-between pb-2">
+      <h2 className="text-2xl font-bold text-foreground tracking-tight leading-none">{selectedYear}</h2>
+
+      <div className="inline-flex items-center gap-2 shrink-0">
+        <Button
+          variant="ghost"
+          size="icon"
+          onClick={handlePrevYear}
+          disabled={!canGoPrev}
+          aria-label="Previous year"
+          className="rounded-full hover:bg-accent/50 transition-colors disabled:opacity-40 disabled:cursor-not-allowed"
+        >
+          <ChevronLeftIcon />
+        </Button>
+
+        <Button
+          variant={isCurrentYear ? "secondary" : "ghost"}
+          onClick={handleToday}
+          disabled={isCurrentYear}
+          aria-label={t("common.today")}
+          className="bg-accent text-accent-foreground hover:bg-accent/50 text-muted-foreground hover:text-foreground h-9 px-4 rounded-full font-medium text-sm transition-colors cursor-default"
+        >
+          {t("common.today")}
+        </Button>
+
+        <Button
+          variant="ghost"
+          size="icon"
+          onClick={handleNextYear}
+          disabled={!canGoNext}
+          aria-label="Next year"
+          className="rounded-full hover:bg-accent/50 transition-colors disabled:opacity-40 disabled:cursor-not-allowed"
+        >
+          <ChevronRightIcon />
+        </Button>
+      </div>
+    </div>
+  );
+};
diff --git a/web/src/components/ActivityCalendar/CalendarPopover.tsx b/web/src/components/ActivityCalendar/CalendarPopover.tsx
new file mode 100644
index 000000000..9abdb9bd3
--- /dev/null
+++ b/web/src/components/ActivityCalendar/CalendarPopover.tsx
@@ -0,0 +1,32 @@
+import { useMemo } from "react";
+import { calculateYearMaxCount, filterDataByYear, generateMonthsForYear } from "@/components/ActivityCalendar";
+import { TooltipProvider } from "@/components/ui/tooltip";
+import { cn } from "@/lib/utils";
+import { CalendarHeader } from "./CalendarHeader";
+import { getMaxYear, MIN_YEAR } from "./constants";
+import { MonthCard } from "./MonthCard";
+import type { CalendarPopoverProps } from "./types";
+
+export const CalendarPopover = ({ selectedYear, data, onYearChange, onDateClick, className }: CalendarPopoverProps) => {
+  const yearData = useMemo(() => filterDataByYear(data, selectedYear), [data, selectedYear]);
+  const months = useMemo(() => generateMonthsForYear(selectedYear), [selectedYear]);
+  const yearMaxCount = useMemo(() => calculateYearMaxCount(yearData), [yearData]);
+  const canGoPrev = selectedYear > MIN_YEAR;
+  const canGoNext = selectedYear < getMaxYear();
+
+  return (
+    <div className={cn("w-full max-w-4xl flex flex-col gap-3 p-3", className)}>
+      <CalendarHeader selectedYear={selectedYear} onYearChange={onYearChange} canGoPrev={canGoPrev} canGoNext={canGoNext} />
+
+      <TooltipProvider>
+        <div className="w-full animate-fade-in">
+          <div className="grid gap-2 sm:gap-2.5 md:gap-3 lg:gap-3 grid-cols-2 sm:grid-cols-3 md:grid-cols-3 lg:grid-cols-4 xl:grid-cols-4">
+            {months.map((month) => (
+              <MonthCard key={month} month={month} data={yearData} maxCount={yearMaxCount} onClick={onDateClick} />
+            ))}
+          </div>
+        </div>
+      </TooltipProvider>
+    </div>
+  );
+};
diff --git a/web/src/components/ActivityCalendar/MonthCard.tsx b/web/src/components/ActivityCalendar/MonthCard.tsx
new file mode 100644
index 000000000..aaea282e1
--- /dev/null
+++ b/web/src/components/ActivityCalendar/MonthCard.tsx
@@ -0,0 +1,17 @@
+import { CompactMonthCalendar, getMonthLabel } from "@/components/ActivityCalendar";
+import { cn } from "@/lib/utils";
+import type { MonthCardProps } from "./types";
+
+export const MonthCard = ({ month, data, maxCount, onClick, className }: MonthCardProps) => {
+  return (
+    <div
+      className={cn(
+        "flex flex-col gap-1 sm:gap-1.5 rounded-lg border bg-card p-1.5 sm:p-2 md:p-2.5 shadow-sm hover:shadow-md hover:border-border/60 transition-all duration-200",
+        className,
+      )}
+    >
+      <div className="text-xs font-semibold text-foreground text-center tracking-tight">{getMonthLabel(month)}</div>
+      <CompactMonthCalendar month={month} data={data} maxCount={maxCount} size="small" onClick={onClick} />
+    </div>
+  );
+};
diff --git a/web/src/components/ActivityCalendar/constants.ts b/web/src/components/ActivityCalendar/constants.ts
index 0c24e882c..1908dc73f 100644
--- a/web/src/components/ActivityCalendar/constants.ts
+++ b/web/src/components/ActivityCalendar/constants.ts
@@ -3,6 +3,9 @@ export const MONTHS_IN_YEAR = 12;
 export const WEEKEND_DAYS = [0, 6] as const;
 export const MIN_COUNT = 1;
 
+export const MIN_YEAR = 2000;
+export const getMaxYear = () => new Date().getFullYear() + 1;
+
 export const INTENSITY_THRESHOLDS = {
   HIGH: 0.75,
   MEDIUM: 0.5,
diff --git a/web/src/components/ActivityCalendar/index.ts b/web/src/components/ActivityCalendar/index.ts
index bb1fd2055..121b21684 100644
--- a/web/src/components/ActivityCalendar/index.ts
+++ b/web/src/components/ActivityCalendar/index.ts
@@ -1,14 +1,19 @@
 export { ActivityCalendar as default } from "./ActivityCalendar";
 export { CalendarCell, type CalendarCellProps } from "./CalendarCell";
+export { CalendarHeader } from "./CalendarHeader";
+export { CalendarPopover } from "./CalendarPopover";
 export { CompactMonthCalendar } from "./CompactMonthCalendar";
 export * from "./constants";
+export { MonthCard } from "./MonthCard";
 export { getTooltipText, type TranslateFunction, useTodayDate, useWeekdayLabels } from "./shared";
 export type {
   CalendarDayCell,
   CalendarDayRow,
   CalendarMatrixResult,
+  CalendarPopoverProps,
   CalendarSize,
   CompactMonthCalendarProps,
+  MonthCardProps,
 } from "./types";
 export { type UseCalendarMatrixParams, useCalendarMatrix } from "./useCalendarMatrix";
 export {
diff --git a/web/src/components/ActivityCalendar/types.ts b/web/src/components/ActivityCalendar/types.ts
index 9b6366d12..aaf9dba16 100644
--- a/web/src/components/ActivityCalendar/types.ts
+++ b/web/src/components/ActivityCalendar/types.ts
@@ -27,3 +27,19 @@ export interface CompactMonthCalendarProps {
   size?: CalendarSize;
   onClick?: (date: string) => void;
 }
+
+export interface MonthCardProps {
+  month: string;
+  data: Record<string, number>;
+  maxCount: number;
+  onClick?: (date: string) => void;
+  className?: string;
+}
+
+export interface CalendarPopoverProps {
+  selectedYear: number;
+  data: Record<string, number>;
+  onYearChange: (year: number) => void;
+  onDateClick: (date: string) => void;
+  className?: string;
+}
diff --git a/web/src/components/Navigation.tsx b/web/src/components/Navigation.tsx
index c5c18888a..3778459bc 100644
--- a/web/src/components/Navigation.tsx
+++ b/web/src/components/Navigation.tsx
@@ -1,4 +1,4 @@
-import { BellIcon, CalendarIcon, EarthIcon, LibraryIcon, PaperclipIcon, UserCircleIcon } from "lucide-react";
+import { BellIcon, EarthIcon, LibraryIcon, PaperclipIcon, UserCircleIcon } from "lucide-react";
 import { NavLink } from "react-router-dom";
 import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/ui/tooltip";
 import useCurrentUser from "@/hooks/useCurrentUser";
@@ -34,12 +34,6 @@ const Navigation = (props: Props) => {
     title: t("common.memos"),
     icon: <LibraryIcon className="w-6 h-auto shrink-0" />,
   };
-  const calendarNavLink: NavLinkItem = {
-    id: "header-calendar",
-    path: Routes.CALENDAR,
-    title: t("common.calendar"),
-    icon: <CalendarIcon className="w-6 h-auto shrink-0" />,
-  };
   const exploreNavLink: NavLinkItem = {
     id: "header-explore",
     path: Routes.EXPLORE,
@@ -76,7 +70,7 @@ const Navigation = (props: Props) => {
   };
 
   const navLinks: NavLinkItem[] = currentUser
-    ? [homeNavLink, calendarNavLink, exploreNavLink, attachmentsNavLink, inboxNavLink]
+    ? [homeNavLink, exploreNavLink, attachmentsNavLink, inboxNavLink]
     : [exploreNavLink, signInNavLink];
 
   return (
diff --git a/web/src/components/StatisticsView/MonthNavigator.tsx b/web/src/components/StatisticsView/MonthNavigator.tsx
index 0533fd1ce..c1dc292b9 100644
--- a/web/src/components/StatisticsView/MonthNavigator.tsx
+++ b/web/src/components/StatisticsView/MonthNavigator.tsx
@@ -1,24 +1,58 @@
-import dayjs from "dayjs";
 import { ChevronLeftIcon, ChevronRightIcon } from "lucide-react";
+import { useState } from "react";
+import { CalendarPopover } from "@/components/ActivityCalendar";
+import { Popover, PopoverContent, PopoverTrigger } from "@/components/ui/popover";
+import useCurrentUser from "@/hooks/useCurrentUser";
+import { useFilteredMemoStats } from "@/hooks/useFilteredMemoStats";
 import i18n from "@/i18n";
+import { addMonths, formatMonth, getMonthFromDate, getYearFromDate, setYearAndMonth } from "@/lib/calendar-utils";
 import type { MonthNavigatorProps } from "@/types/statistics";
 
 export const MonthNavigator = ({ visibleMonth, onMonthChange }: MonthNavigatorProps) => {
-  const currentMonth = dayjs(visibleMonth).toDate();
+  const currentUser = useCurrentUser();
+  const [isOpen, setIsOpen] = useState(false);
+  const currentMonth = new Date(visibleMonth);
+  const currentYear = getYearFromDate(visibleMonth);
+  const currentMonthNum = getMonthFromDate(visibleMonth);
+
+  const { statistics } = useFilteredMemoStats({
+    userName: currentUser?.name,
+  });
 
   const handlePrevMonth = () => {
-    onMonthChange(dayjs(visibleMonth).subtract(1, "month").format("YYYY-MM"));
+    onMonthChange(addMonths(visibleMonth, -1));
   };
 
   const handleNextMonth = () => {
-    onMonthChange(dayjs(visibleMonth).add(1, "month").format("YYYY-MM"));
+    onMonthChange(addMonths(visibleMonth, 1));
+  };
+
+  const handleDateClick = (date: string) => {
+    onMonthChange(formatMonth(date));
+    setIsOpen(false);
+  };
+
+  const handleYearChange = (year: number) => {
+    onMonthChange(setYearAndMonth(year, currentMonthNum));
   };
 
   return (
     <div className="w-full mb-1 flex flex-row justify-between items-center gap-1">
-      <span className="relative text-sm text-muted-foreground">
-        {currentMonth.toLocaleString(i18n.language, { year: "numeric", month: "long" })}
-      </span>
+      <Popover open={isOpen} onOpenChange={setIsOpen}>
+        <PopoverTrigger asChild>
+          <span className="relative text-sm text-muted-foreground cursor-pointer hover:text-foreground transition-colors">
+            {currentMonth.toLocaleString(i18n.language, { year: "numeric", month: "long" })}
+          </span>
+        </PopoverTrigger>
+        <PopoverContent className="p-0" align="start">
+          <CalendarPopover
+            selectedYear={currentYear}
+            data={statistics.activityStats}
+            onYearChange={handleYearChange}
+            onDateClick={handleDateClick}
+          />
+        </PopoverContent>
+      </Popover>
       <div className="flex justify-end items-center shrink-0 gap-1">
         <button className="cursor-pointer hover:opacity-80 transition-opacity" onClick={handlePrevMonth} aria-label="Previous month">
           <ChevronLeftIcon className="w-5 h-auto shrink-0 opacity-40" />
diff --git a/web/src/lib/calendar-utils.ts b/web/src/lib/calendar-utils.ts
new file mode 100644
index 000000000..96a3eb2f4
--- /dev/null
+++ b/web/src/lib/calendar-utils.ts
@@ -0,0 +1,23 @@
+import dayjs from "dayjs";
+
+export const MONTH_DATE_FORMAT = "YYYY-MM" as const;
+
+export const formatMonth = (date: Date | string): string => {
+  return dayjs(date).format(MONTH_DATE_FORMAT);
+};
+
+export const getYearFromDate = (date: Date | string): number => {
+  return dayjs(date).year();
+};
+
+export const getMonthFromDate = (date: Date | string): number => {
+  return dayjs(date).month();
+};
+
+export const addMonths = (date: Date | string, count: number): string => {
+  return dayjs(date).add(count, "month").format(MONTH_DATE_FORMAT);
+};
+
+export const setYearAndMonth = (year: number, month: number): string => {
+  return dayjs().year(year).month(month).format(MONTH_DATE_FORMAT);
+};
diff --git a/web/src/pages/Calendar.tsx b/web/src/pages/Calendar.tsx
deleted file mode 100644
index a09b61cde..000000000
--- a/web/src/pages/Calendar.tsx
+++ /dev/null
@@ -1,144 +0,0 @@
-import { ChevronLeftIcon, ChevronRightIcon } from "lucide-react";
-import { useMemo, useState } from "react";
-import {
-  CompactMonthCalendar,
-  calculateYearMaxCount,
-  filterDataByYear,
-  generateMonthsForYear,
-  getMonthLabel,
-} from "@/components/ActivityCalendar";
-import MobileHeader from "@/components/MobileHeader";
-import { Button } from "@/components/ui/button";
-import { TooltipProvider } from "@/components/ui/tooltip";
-import { useDateFilterNavigation } from "@/hooks";
-import useCurrentUser from "@/hooks/useCurrentUser";
-import { useFilteredMemoStats } from "@/hooks/useFilteredMemoStats";
-import { cn } from "@/lib/utils";
-import { useTranslate } from "@/utils/i18n";
-
-const MIN_YEAR = 2000;
-const MAX_YEAR = new Date().getFullYear() + 1;
-
-const Calendar = () => {
-  const currentUser = useCurrentUser();
-  const t = useTranslate();
-  const navigateToDateFilter = useDateFilterNavigation();
-  const [selectedYear, setSelectedYear] = useState(new Date().getFullYear());
-
-  const { statistics, loading } = useFilteredMemoStats({
-    userName: currentUser?.name,
-  });
-
-  const yearData = useMemo(() => filterDataByYear(statistics.activityStats, selectedYear), [statistics.activityStats, selectedYear]);
-
-  const months = useMemo(() => generateMonthsForYear(selectedYear), [selectedYear]);
-
-  const yearMaxCount = useMemo(() => calculateYearMaxCount(yearData), [yearData]);
-
-  const currentYear = useMemo(() => new Date().getFullYear(), []);
-  const isCurrentYear = selectedYear === currentYear;
-
-  const handlePrevYear = () => {
-    if (selectedYear > MIN_YEAR) {
-      setSelectedYear(selectedYear - 1);
-    }
-  };
-
-  const handleNextYear = () => {
-    if (selectedYear < MAX_YEAR) {
-      setSelectedYear(selectedYear + 1);
-    }
-  };
-
-  const handleToday = () => {
-    setSelectedYear(currentYear);
-  };
-
-  const canGoPrev = selectedYear > MIN_YEAR;
-  const canGoNext = selectedYear < MAX_YEAR;
-
-  return (
-    <section className="relative w-full min-h-full flex flex-col justify-start items-center bg-background">
-      <MobileHeader />
-      <div className="relative w-full flex flex-col items-center px-3 sm:px-4 md:px-6 lg:px-8 pb-8">
-        <div className="w-full max-w-7xl flex flex-col gap-3 sm:gap-4 py-3 sm:py-4">
-          <div className="flex items-center justify-between pb-2">
-            <h1 className="text-2xl sm:text-3xl md:text-4xl font-bold text-foreground tracking-tight leading-none">{selectedYear}</h1>
-
-            <div className="inline-flex items-center gap-2 shrink-0">
-              <Button
-                variant="ghost"
-                size="icon"
-                onClick={handlePrevYear}
-                disabled={!canGoPrev}
-                aria-label="Previous year"
-                className="rounded-full hover:bg-accent/50 transition-colors disabled:opacity-40 disabled:cursor-not-allowed"
-              >
-                <ChevronLeftIcon />
-              </Button>
-
-              <Button
-                variant={isCurrentYear ? "secondary" : "ghost"}
-                onClick={handleToday}
-                disabled={isCurrentYear}
-                aria-label={t("common.today")}
-                className={cn(
-                  "h-9 px-4 rounded-full font-medium text-sm transition-colors",
-                  isCurrentYear
-                    ? "bg-accent text-accent-foreground cursor-default"
-                    : "hover:bg-accent/50 text-muted-foreground hover:text-foreground",
-                )}
-              >
-                {t("common.today")}
-              </Button>
-
-              <Button
-                variant="ghost"
-                size="icon"
-                onClick={handleNextYear}
-                disabled={!canGoNext}
-                aria-label="Next year"
-                className="rounded-full hover:bg-accent/50 transition-colors disabled:opacity-40 disabled:cursor-not-allowed"
-              >
-                <ChevronRightIcon />
-              </Button>
-            </div>
-          </div>
-
-          {loading ? (
-            <div className="w-full flex items-center justify-center py-12">
-              <div className="flex flex-col items-center gap-3">
-                <div className="h-8 w-8 animate-spin rounded-full border-4 border-primary border-t-transparent" />
-                <p className="text-sm text-muted-foreground">Loading calendar...</p>
-              </div>
-            </div>
-          ) : (
-            <TooltipProvider>
-              <div className="w-full animate-fade-in">
-                <div className="grid gap-2 sm:gap-2.5 md:gap-3 lg:gap-3 grid-cols-2 sm:grid-cols-3 md:grid-cols-3 lg:grid-cols-4 xl:grid-cols-4">
-                  {months.map((month) => (
-                    <div
-                      key={month}
-                      className="flex flex-col gap-1 sm:gap-1.5 rounded-lg border bg-card p-1.5 sm:p-2 md:p-2.5 shadow-sm hover:shadow-md hover:border-border/60 transition-all duration-200"
-                    >
-                      <div className="text-xs font-semibold text-foreground text-center tracking-tight">{getMonthLabel(month)}</div>
-                      <CompactMonthCalendar
-                        month={month}
-                        data={yearData}
-                        maxCount={yearMaxCount}
-                        size="small"
-                        onClick={navigateToDateFilter}
-                      />
-                    </div>
-                  ))}
-                </div>
-              </div>
-            </TooltipProvider>
-          )}
-        </div>
-      </div>
-    </section>
-  );
-};
-
-export default Calendar;
diff --git a/web/src/router/index.tsx b/web/src/router/index.tsx
index 655675f71..5bf27269f 100644
--- a/web/src/router/index.tsx
+++ b/web/src/router/index.tsx
@@ -9,7 +9,6 @@ import Home from "@/pages/Home";
 const AdminSignIn = lazy(() => import("@/pages/AdminSignIn"));
 const Archived = lazy(() => import("@/pages/Archived"));
 const AuthCallback = lazy(() => import("@/pages/AuthCallback"));
-const Calendar = lazy(() => import("@/pages/Calendar"));
 const Explore = lazy(() => import("@/pages/Explore"));
 const Inboxes = lazy(() => import("@/pages/Inboxes"));
 const MemoDetail = lazy(() => import("@/pages/MemoDetail"));
@@ -115,14 +114,6 @@ const router = createBrowserRouter([
               </Suspense>
             ),
           },
-          {
-            path: Routes.CALENDAR,
-            element: (
-              <Suspense fallback={<Skeleton type="route" showEditor={false} />}>
-                <Calendar />
-              </Suspense>
-            ),
-          },
           {
             path: Routes.INBOX,
             element: (
diff --git a/web/src/router/routes.ts b/web/src/router/routes.ts
index 8f0058b57..74502cc2a 100644
--- a/web/src/router/routes.ts
+++ b/web/src/router/routes.ts
@@ -1,7 +1,6 @@
 export const ROUTES = {
   ROOT: "/",
   ATTACHMENTS: "/attachments",
-  CALENDAR: "/calendar",
   INBOX: "/inbox",
   ARCHIVED: "/archived",
   SETTING: "/setting",