diff --git a/frontend/src/components/calendar/CalendarPage.tsx b/frontend/src/components/calendar/CalendarPage.tsx
index 5190351..609bdfe 100644
--- a/frontend/src/components/calendar/CalendarPage.tsx
+++ b/frontend/src/components/calendar/CalendarPage.tsx
@@ -14,7 +14,9 @@ export default function CalendarPage() {
   const queryClient = useQueryClient();
   const [showForm, setShowForm] = useState(false);
   const [editingEvent, setEditingEvent] = useState<CalendarEvent | null>(null);
-  const [selectedDate, setSelectedDate] = useState<string | null>(null);
+  const [selectedStart, setSelectedStart] = useState<string | null>(null);
+  const [selectedEnd, setSelectedEnd] = useState<string | null>(null);
+  const [selectedAllDay, setSelectedAllDay] = useState(false);
 
   const { data: events = [] } = useQuery({
     queryKey: ['calendar-events'],
@@ -24,8 +26,43 @@ export default function CalendarPage() {
     },
   });
 
-  const eventDropMutation = useMutation({
-    mutationFn: async ({ id, start, end, allDay }: { id: number; start: string; end: string; allDay: boolean }) => {
+  const toLocalDatetime = (d: Date): string => {
+    const pad = (n: number) => n.toString().padStart(2, '0');
+    return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}:${pad(d.getSeconds())}`;
+  };
+
+  const updateEventTimes = (
+    id: number,
+    start: string,
+    end: string,
+    allDay: boolean,
+    revert: () => void,
+  ) => {
+    // Optimistically update cache so re-renders don't snap back
+    queryClient.setQueryData<CalendarEvent[]>(['calendar-events'], (old) =>
+      old?.map((e) =>
+        e.id === id
+          ? { ...e, start_datetime: start, end_datetime: end, all_day: allDay }
+          : e,
+      ),
+    );
+
+    eventMutation.mutate({ id, start, end, allDay, revert });
+  };
+
+  const eventMutation = useMutation({
+    mutationFn: async ({
+      id,
+      start,
+      end,
+      allDay,
+    }: {
+      id: number;
+      start: string;
+      end: string;
+      allDay: boolean;
+      revert: () => void;
+    }) => {
       const response = await api.put(`/events/${id}`, {
         start_datetime: start,
         end_datetime: end,
@@ -35,11 +72,12 @@ export default function CalendarPage() {
     },
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['calendar-events'] });
-      toast.success('Event moved');
+      toast.success('Event updated');
     },
-    onError: (error) => {
+    onError: (error, variables) => {
+      variables.revert();
       queryClient.invalidateQueries({ queryKey: ['calendar-events'] });
-      toast.error(getErrorMessage(error, 'Failed to move event'));
+      toast.error(getErrorMessage(error, 'Failed to update event'));
     },
   });
 
@@ -61,31 +99,49 @@ export default function CalendarPage() {
     }
   };
 
-  const toLocalDatetime = (d: Date): string => {
-    const pad = (n: number) => n.toString().padStart(2, '0');
-    return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}:${pad(d.getSeconds())}`;
-  };
-
   const handleEventDrop = (info: EventDropArg) => {
     const id = parseInt(info.event.id);
     const start = info.event.allDay
       ? info.event.startStr
-      : info.event.start ? toLocalDatetime(info.event.start) : info.event.startStr;
+      : info.event.start
+        ? toLocalDatetime(info.event.start)
+        : info.event.startStr;
     const end = info.event.allDay
       ? info.event.endStr || info.event.startStr
-      : info.event.end ? toLocalDatetime(info.event.end) : start;
-    eventDropMutation.mutate({ id, start, end, allDay: info.event.allDay });
+      : info.event.end
+        ? toLocalDatetime(info.event.end)
+        : start;
+    updateEventTimes(id, start, end, info.event.allDay, info.revert);
+  };
+
+  const handleEventResize = (info: { event: EventDropArg['event']; revert: () => void }) => {
+    const id = parseInt(info.event.id);
+    const start = info.event.allDay
+      ? info.event.startStr
+      : info.event.start
+        ? toLocalDatetime(info.event.start)
+        : info.event.startStr;
+    const end = info.event.allDay
+      ? info.event.endStr || info.event.startStr
+      : info.event.end
+        ? toLocalDatetime(info.event.end)
+        : start;
+    updateEventTimes(id, start, end, info.event.allDay, info.revert);
   };
 
   const handleDateSelect = (selectInfo: DateSelectArg) => {
-    setSelectedDate(selectInfo.startStr);
+    setSelectedStart(selectInfo.startStr);
+    setSelectedEnd(selectInfo.endStr);
+    setSelectedAllDay(selectInfo.allDay);
     setShowForm(true);
   };
 
   const handleCloseForm = () => {
     setShowForm(false);
     setEditingEvent(null);
-    setSelectedDate(null);
+    setSelectedStart(null);
+    setSelectedEnd(null);
+    setSelectedAllDay(false);
   };
 
   return (
@@ -112,6 +168,7 @@ export default function CalendarPage() {
             weekends={true}
             eventClick={handleEventClick}
             eventDrop={handleEventDrop}
+            eventResize={handleEventResize}
             select={handleDateSelect}
             height="auto"
           />
@@ -119,7 +176,13 @@ export default function CalendarPage() {
       </div>
 
       {showForm && (
-        <EventForm event={editingEvent} initialDate={selectedDate} onClose={handleCloseForm} />
+        <EventForm
+          event={editingEvent}
+          initialStart={selectedStart}
+          initialEnd={selectedEnd}
+          initialAllDay={selectedAllDay}
+          onClose={handleCloseForm}
+        />
       )}
     </div>
   );
diff --git a/frontend/src/components/calendar/EventForm.tsx b/frontend/src/components/calendar/EventForm.tsx
index da552f0..0d37c96 100644
--- a/frontend/src/components/calendar/EventForm.tsx
+++ b/frontend/src/components/calendar/EventForm.tsx
@@ -20,7 +20,9 @@ import { Checkbox } from '@/components/ui/checkbox';
 
 interface EventFormProps {
   event: CalendarEvent | null;
-  initialDate?: string | null;
+  initialStart?: string | null;
+  initialEnd?: string | null;
+  initialAllDay?: boolean;
   onClose: () => void;
 }
 
@@ -54,11 +56,11 @@ function formatForInput(dt: string, allDay: boolean, fallbackTime: string = '09:
   return allDay ? toDateOnly(dt) : toDatetimeLocal(dt, fallbackTime);
 }
 
-export default function EventForm({ event, initialDate, onClose }: EventFormProps) {
+export default function EventForm({ event, initialStart, initialEnd, initialAllDay, onClose }: EventFormProps) {
   const queryClient = useQueryClient();
-  const isAllDay = event?.all_day ?? false;
-  const rawStart = event?.start_datetime || initialDate || '';
-  const rawEnd = event?.end_datetime || initialDate || '';
+  const isAllDay = event?.all_day ?? initialAllDay ?? false;
+  const rawStart = event?.start_datetime || initialStart || '';
+  const rawEnd = event?.end_datetime || initialEnd || '';
   const [formData, setFormData] = useState({
     title: event?.title || '',
     description: event?.description || '',