diff --git a/src/EventListener/ProjectsListener.php b/src/EventListener/ProjectsListener.php
new file mode 100644
index 0000000..e44b22c
--- /dev/null
+++ b/src/EventListener/ProjectsListener.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace App\EventListener;
+
+use App\Entity\Project\Project;
+use App\Entity\Project\ProjectStatus;
+use App\Service\Project\CalendarService;
+use Doctrine\Bundle\DoctrineBundle\Attribute\AsEntityListener;
+use Doctrine\ORM\Event\PreUpdateEventArgs;
+use Doctrine\ORM\Events;
+
+#[AsEntityListener(
+    event: Events::preUpdate,
+    method: 'preUpdate',
+    entity: Project::class
+)]
+final class ProjectsListener
+{
+    public function __construct(
+        private CalendarService $calendarService,
+    ) {}
+
+    public function preUpdate(
+        Project $project,
+        PreUpdateEventArgs $event,
+    ) {
+        if (!$event->hasChangedField('status')) {
+            return;
+        }
+
+        if ($project->getStatus() === ProjectStatus::InCampaign) {
+            $calendar = $this->calendarService->makeCalendar($project);
+
+            $project->setCalendar($calendar);
+        }
+    }
+}
diff --git a/src/Service/Project/CalendarService.php b/src/Service/Project/CalendarService.php
new file mode 100644
index 0000000..b77b655
--- /dev/null
+++ b/src/Service/Project/CalendarService.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Service\Project;
+
+use App\Entity\Project\Project;
+use App\Entity\Project\ProjectCalendar;
+use App\Entity\Project\ProjectDeadline;
+
+class CalendarService
+{
+    public function makeCalendar(
+        Project $project,
+        int $minimumTtl = 40,
+        int $optimumTtl = 40,
+    ): ProjectCalendar {
+        $release = new \DateTimeImmutable();
+        $minimumTtl = \DateInterval::createFromDateString(\sprintf('%d days', $minimumTtl));
+        $optimumTtl = \DateInterval::createFromDateString(\sprintf('%d days', $optimumTtl));
+
+        $calendar = new ProjectCalendar();
+        $calendar->release = $release;
+
+        switch ($project->getDeadline()) {
+            case ProjectDeadline::Minimum:
+                $calendar->minimum = $release->add($minimumTtl);
+                break;
+            case ProjectDeadline::Optimum:
+                $calendar->minimum = $release->add($minimumTtl);
+                $calendar->optimum = $calendar->minimum->add($optimumTtl);
+                break;
+        }
+
+        return $calendar;
+    }
+}
diff --git a/src/State/Project/ProjectStateProcessor.php b/src/State/Project/ProjectStateProcessor.php
index 764e2e2..54a4305 100644
--- a/src/State/Project/ProjectStateProcessor.php
+++ b/src/State/Project/ProjectStateProcessor.php
@@ -23,7 +23,7 @@ class ProjectStateProcessor implements ProcessorInterface
 
     /**
      * @param ProjectCreateDto|ProjectUpdateDto $data
-     * @param array{id: int} $uriVariables
+     * @param array{id: int}                    $uriVariables
      *
      * @return ProjectApiResource|null
      */