diff --git a/addons/project/static/src/views/project_calendar/project_calendar_controller.js b/addons/project/static/src/views/project_calendar/project_calendar_controller.js
index 3fe595ad621..24e61059f9c 100644
--- a/addons/project/static/src/views/project_calendar/project_calendar_controller.js
+++ b/addons/project/static/src/views/project_calendar/project_calendar_controller.js
@@ -1,8 +1,13 @@
 /** @odoo-module **/
 
 import { CalendarController } from "@web/views/calendar/calendar_controller";
+import { ProjectCalendarFilterPanel } from "./project_calendar_filter_panel/project_calendar_filter_panel";
 
 export class ProjectCalendarController extends CalendarController {
+    static components = {
+        ...ProjectCalendarController.components,
+        FilterPanel: ProjectCalendarFilterPanel,
+    };
     setup() {
         super.setup(...arguments);
         this.displayName += this.env._t(" - Tasks by Deadline");
diff --git a/addons/project/static/src/views/project_calendar/project_calendar_filter_panel/project_calendar_filter_panel.js b/addons/project/static/src/views/project_calendar/project_calendar_filter_panel/project_calendar_filter_panel.js
new file mode 100644
index 00000000000..67e3f3c35f3
--- /dev/null
+++ b/addons/project/static/src/views/project_calendar/project_calendar_filter_panel/project_calendar_filter_panel.js
@@ -0,0 +1,9 @@
+/** @odoo-module **/
+
+import { CalendarFilterPanel } from "@web/views/calendar/filter_panel/calendar_filter_panel";
+
+export class ProjectCalendarFilterPanel extends CalendarFilterPanel { }
+
+ProjectCalendarFilterPanel.subTemplates = {
+    filter: "project.ProjectCalendarFilterPanel.filter",
+};
diff --git a/addons/project/static/src/views/project_calendar/project_calendar_filter_panel/project_calendar_filter_panel.xml b/addons/project/static/src/views/project_calendar/project_calendar_filter_panel/project_calendar_filter_panel.xml
new file mode 100644
index 00000000000..042cc05384e
--- /dev/null
+++ b/addons/project/static/src/views/project_calendar/project_calendar_filter_panel/project_calendar_filter_panel.xml
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<templates xml:space="preserve">
+
+    <t t-name="project.ProjectCalendarFilterPanel.filter" t-inherit="web.CalendarFilterPanel.filter" t-inherit-mode="primary" owl="1">
+        <xpath expr="//span[@t-esc='filter.label']" position="before">
+            <span t-if="props.model.isCheckProject and !filter.value" class="text-danger pe-1">
+                <i class="fa fa-lock">
+            </t>
+        </xpath>
+    </t>
+
+</templates>
diff --git a/addons/project/static/src/views/project_calendar/project_calendar_model.js b/addons/project/static/src/views/project_calendar/project_calendar_model.js
new file mode 100644
index 00000000000..c68b775601a
--- /dev/null
+++ b/addons/project/static/src/views/project_calendar/project_calendar_model.js
@@ -0,0 +1,16 @@
+/** @odoo-module */
+
+import { CalendarModel } from '@web/views/calendar/calendar_model';
+
+export class ProjectCalendarModel extends CalendarModel {
+    /**
+     * @override
+     */
+    get defaultFilterLabel() {
+        this.isCheckProject = 'project_id' in this.meta.filtersInfo;
+        if (this.isCheckProject) {
+            return this.env._t("Private");
+        }
+        return super.onWillStart();
+    }
+}
diff --git a/addons/project/static/src/views/project_calendar/project_calendar_view.js b/addons/project/static/src/views/project_calendar/project_calendar_view.js
index f418f837e6b..b48949e273b 100644
--- a/addons/project/static/src/views/project_calendar/project_calendar_view.js
+++ b/addons/project/static/src/views/project_calendar/project_calendar_view.js
@@ -4,10 +4,12 @@ import { registry } from "@web/core/registry";
 import { calendarView } from "@web/views/calendar/calendar_view";
 import { ProjectCalendarController } from "@project/views/project_calendar/project_calendar_controller";
 import { ProjectControlPanel } from "@project/components/project_control_panel/project_control_panel";
+import { ProjectCalendarModel } from "./project_calendar_model";
 
 export const projectCalendarView = {
     ...calendarView,
     Controller: ProjectCalendarController,
+    Model: ProjectCalendarModel,
     ControlPanel: ProjectControlPanel,
 };
 registry.category("views").add("project_calendar", projectCalendarView);
diff --git a/addons/web/static/src/views/calendar/calendar_model.js b/addons/web/static/src/views/calendar/calendar_model.js
index 1f0a00cb1e0..1a17ac74841 100644
--- a/addons/web/static/src/views/calendar/calendar_model.js
+++ b/addons/web/static/src/views/calendar/calendar_model.js
@@ -139,6 +139,10 @@ export class CalendarModel extends Model {
         return this.meta.quickCreateFormViewId;
     }
 
+    get defaultFilterLabel() {
+        return _t("Undefined");
+    }
+
     //--------------------------------------------------------------------------
 
     async createFilter(fieldName, filterValue) {
@@ -732,7 +736,7 @@ export class CalendarModel extends Model {
             type: "dynamic",
             recordId: null,
             value,
-            label: formatter(rawValue, { field }) || _t("Undefined"),
+            label: formatter(rawValue, { field }) || this.defaultFilterLabel,
             active: previousFilter ? previousFilter.active : true,
             canRemove: false,
             colorIndex,