diff --git a/frontend/src/components/common/CalendarDay.test.tsx b/frontend/src/components/common/CalendarDay.test.tsx
index a536892..85574d6 100644
--- a/frontend/src/components/common/CalendarDay.test.tsx
+++ b/frontend/src/components/common/CalendarDay.test.tsx
@@ -93,4 +93,20 @@ describe('CalendarDay', () => {
     const events = queryByTestId('calendar-day-events')
     expect(events).not.toBeInTheDocument()
   })
+
+  it('applies today class when isToday is true', () => {
+    const { getByTestId } = render(
+      <CalendarDay date="2026-06-15" isToday={true} />
+    )
+    const day = getByTestId('calendar-day')
+    expect(day).toHaveClass('calendar-day--today')
+  })
+
+  it('does not apply today class when isToday is false', () => {
+    const { getByTestId } = render(
+      <CalendarDay date="2026-06-15" isToday={false} />
+    )
+    const day = getByTestId('calendar-day')
+    expect(day).not.toHaveClass('calendar-day--today')
+  })
 })
diff --git a/frontend/src/pages/Calendar.test.tsx b/frontend/src/pages/Calendar.test.tsx
new file mode 100644
index 0000000..c068cd2
--- /dev/null
+++ b/frontend/src/pages/Calendar.test.tsx
@@ -0,0 +1,146 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { render, screen, fireEvent } from '@testing-library/react'
+import { Calendar } from './Calendar'
+import { useWorkspace } from '@/context'
+import { usePlannedDays } from '@/hooks'
+
+vi.mock('@/context', () => ({
+  useWorkspace: vi.fn(),
+}))
+
+vi.mock('@/hooks', () => ({
+  usePlannedDays: vi.fn(),
+}))
+
+vi.mock('@/components/layout/Layout', () => ({
+  Layout: ({ children }: { children: React.ReactNode }) => <div>{children}</div>,
+}))
+
+vi.mock('@/components/common/LoadingSpinner', () => ({
+  LoadingSpinner: () => <div>Loading...</div>,
+}))
+
+vi.mock('@/components/modals/PlannedDayModal', () => ({
+  PlannedDayModal: () => <div data-testid="modal" />,
+}))
+
+describe('Calendar', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  const mockWorkspace = {
+    isLoading: false,
+    selectedChildId: 'child-1',
+    workspace: { id: 'ws-1' },
+    personalDataUuid: 'person-1',
+  }
+
+  const mockPlannedDays = {
+    data: [],
+    isLoading: false,
+    add: vi.fn(),
+    update: vi.fn(),
+    remove: vi.fn(),
+  }
+
+  it('renders loading state while data is loading', () => {
+    ;(useWorkspace as any).mockReturnValue({ ...mockWorkspace, isLoading: true })
+    ;(usePlannedDays as any).mockReturnValue(mockPlannedDays)
+
+    render(<Calendar />)
+    expect(screen.getByText('Loading...')).toBeInTheDocument()
+  })
+
+  it('renders 7 weekday headers in Monday-first Swedish order', () => {
+    ;(useWorkspace as any).mockReturnValue(mockWorkspace)
+    ;(usePlannedDays as any).mockReturnValue(mockPlannedDays)
+
+    render(<Calendar />)
+    const weekdays = screen.getAllByText(/^(Mån|Tis|Ons|Tor|Fre|Lör|Sön)$/)
+    expect(weekdays).toHaveLength(7)
+
+    const weekdayOrder = ['Mån', 'Tis', 'Ons', 'Tor', 'Fre', 'Lör', 'Sön']
+    weekdays.forEach((el, idx) => {
+      expect(el.textContent).toBe(weekdayOrder[idx])
+    })
+  })
+
+  it('renders day cells for all weeks in a month', () => {
+    ;(useWorkspace as any).mockReturnValue(mockWorkspace)
+    ;(usePlannedDays as any).mockReturnValue(mockPlannedDays)
+
+    render(<Calendar />)
+
+    const calendarDays = screen.getAllByTestId('calendar-day')
+    expect(calendarDays.length).toBeGreaterThan(28)
+    expect(calendarDays.length % 7).toBe(0)
+  })
+
+  it('marks Sunday-starting month (March 2026) correctly with 7-column grid', () => {
+    ;(useWorkspace as any).mockReturnValue(mockWorkspace)
+    ;(usePlannedDays as any).mockReturnValue(mockPlannedDays)
+
+    const { rerender } = render(<Calendar />)
+    expect(screen.getByTestId('calendar')).toBeInTheDocument()
+    rerender(<Calendar />)
+
+    const calendarDays = screen.getAllByTestId('calendar-day')
+    expect(calendarDays.length % 7).toBe(0)
+  })
+
+  it('opens modal when clicking a current-month day', () => {
+    ;(useWorkspace as any).mockReturnValue(mockWorkspace)
+    ;(usePlannedDays as any).mockReturnValue(mockPlannedDays)
+
+    render(<Calendar />)
+
+    const calendarDays = screen.getAllByTestId('calendar-day')
+    const currentMonthDay = calendarDays.find((el) => !el.classList.contains('calendar-day--disabled'))
+
+    if (currentMonthDay) {
+      fireEvent.click(currentMonthDay)
+      expect(screen.getByTestId('modal')).toBeInTheDocument()
+    }
+  })
+
+  it('does not open modal when clicking disabled (non-current-month) day', () => {
+    ;(useWorkspace as any).mockReturnValue(mockWorkspace)
+    ;(usePlannedDays as any).mockReturnValue(mockPlannedDays)
+
+    render(<Calendar />)
+
+    const calendarDays = screen.getAllByTestId('calendar-day')
+    const disabledDay = calendarDays.find((el) => el.classList.contains('calendar-day--disabled'))
+
+    if (disabledDay) {
+      fireEvent.click(disabledDay)
+      expect(disabledDay).toHaveClass('calendar-day--disabled')
+    }
+  })
+
+  it('displays current month title', () => {
+    ;(useWorkspace as any).mockReturnValue(mockWorkspace)
+    ;(usePlannedDays as any).mockReturnValue(mockPlannedDays)
+
+    render(<Calendar />)
+
+    const title = screen.getByRole('heading', { level: 2 })
+    expect(title.textContent).toMatch(/\d{4}/)
+  })
+
+  it('handles next/prev month navigation', () => {
+    ;(useWorkspace as any).mockReturnValue(mockWorkspace)
+    ;(usePlannedDays as any).mockReturnValue(mockPlannedDays)
+
+    render(<Calendar />)
+
+    const nextButton = screen.getByLabelText('Next month')
+    fireEvent.click(nextButton)
+
+    const prevButton = screen.getByLabelText('Previous month')
+    fireEvent.click(prevButton)
+
+    expect(screen.getByTestId('calendar')).toBeInTheDocument()
+  })
+})