diff --git a/app/Http/Controllers/Api/Remote/Backups/BackupSizeController.php b/app/Http/Controllers/Api/Remote/Backups/BackupSizeController.php
new file mode 100644
index 000000000..ad5fc0958
--- /dev/null
+++ b/app/Http/Controllers/Api/Remote/Backups/BackupSizeController.php
@@ -0,0 +1,145 @@
+<?php
+
+namespace Pterodactyl\Http\Controllers\Api\Remote\Backups;
+
+use Illuminate\Http\Request;
+use Pterodactyl\Models\Backup;
+use Pterodactyl\Models\Server;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Validation\Rule;
+use Pterodactyl\Http\Controllers\Controller;
+use Pterodactyl\Exceptions\Http\HttpForbiddenException;
+use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
+
+class BackupSizeController extends Controller
+{
+    /**
+     * Updates backup sizes after deduplication recalculation from Elytra.
+     * This endpoint is called when Rustic backups are deleted and remaining
+     * backup sizes need to be recalculated to account for deduplication.
+     */
+    public function update(Request $request, string $uuid): JsonResponse
+    {
+        // Get the node associated with the request
+        /** @var \Pterodactyl\Models\Node $node */
+        $node = $request->attributes->get('node');
+
+        // Find the server
+        /** @var Server $server */
+        $server = Server::query()
+            ->where('uuid', $uuid)
+            ->firstOrFail();
+
+        // Check that the server belongs to the node making the request
+        if ($server->node_id !== $node->id) {
+            throw new HttpForbiddenException('You do not have permission to access that server.');
+        }
+
+        // Validate the request data
+        $validatedData = $request->validate([
+            'server_uuid' => ['required', 'string', Rule::in([$uuid])],
+            'backups' => ['required', 'array', 'min:1'],
+            'backups.*.backup_uuid' => ['required', 'string', 'uuid'],
+            'backups.*.new_size' => ['required', 'integer', 'min:0'],
+        ]);
+
+        $updatedCount = 0;
+        $errors = [];
+        $backupsToUpdate = [];
+
+        // First pass: validate all backups and prepare updates
+        foreach ($validatedData['backups'] as $backupData) {
+            /** @var Backup $backup */
+            $backup = Backup::query()
+                ->where('uuid', $backupData['backup_uuid'])
+                ->where('server_id', $server->id)
+                ->first();
+
+            if (!$backup) {
+                $errors[] = [
+                    'backup_uuid' => $backupData['backup_uuid'],
+                    'error' => 'Backup not found or does not belong to this server'
+                ];
+                continue;
+            }
+
+            // Only update successful backups
+            if (!$backup->is_successful) {
+                $errors[] = [
+                    'backup_uuid' => $backupData['backup_uuid'],
+                    'error' => 'Cannot update size of unsuccessful backup'
+                ];
+                continue;
+            }
+
+            $backupsToUpdate[] = [
+                'backup' => $backup,
+                'old_size' => $backup->bytes,
+                'new_size' => $backupData['new_size'],
+            ];
+        }
+
+        // If we have validation errors but some backups can be updated, proceed with partial update
+        // If ALL backups failed validation, return early without making any changes
+        if (empty($backupsToUpdate)) {
+            return new JsonResponse([
+                'updated_count' => 0,
+                'total_requested' => count($validatedData['backups']),
+                'errors' => $errors,
+            ], JsonResponse::HTTP_BAD_REQUEST);
+        }
+
+        // Second pass: perform all updates in a transaction for atomicity
+        try {
+            \DB::transaction(function () use ($backupsToUpdate, &$updatedCount, $server) {
+                foreach ($backupsToUpdate as $updateData) {
+                    $backup = $updateData['backup'];
+                    $oldSize = $updateData['old_size'];
+                    $newSize = $updateData['new_size'];
+
+                    $backup->update(['bytes' => $newSize]);
+                    $updatedCount++;
+
+                    \Log::info('Updated backup size after deduplication recalculation', [
+                        'backup_uuid' => $backup->uuid,
+                        'server_uuid' => $server->uuid,
+                        'old_size' => $oldSize,
+                        'new_size' => $newSize,
+                        'size_difference' => $newSize - $oldSize,
+                    ]);
+                }
+            });
+        } catch (\Exception $e) {
+            \Log::error('Failed to update backup sizes in transaction', [
+                'server_uuid' => $server->uuid,
+                'error' => $e->getMessage(),
+            ]);
+
+            return new JsonResponse([
+                'updated_count' => 0,
+                'total_requested' => count($validatedData['backups']),
+                'errors' => [['error' => 'Transaction failed: ' . $e->getMessage()]],
+            ], JsonResponse::HTTP_INTERNAL_SERVER_ERROR);
+        }
+
+        \Log::info('Backup size recalculation completed', [
+            'server_uuid' => $server->uuid,
+            'total_backups' => count($validatedData['backups']),
+            'updated_count' => $updatedCount,
+            'error_count' => count($errors),
+        ]);
+
+        $responseData = [
+            'updated_count' => $updatedCount,
+            'total_requested' => count($validatedData['backups']),
+        ];
+
+        if (!empty($errors)) {
+            $responseData['errors'] = $errors;
+        }
+
+        $statusCode = $updatedCount > 0 ? JsonResponse::HTTP_OK : JsonResponse::HTTP_BAD_REQUEST;
+        return new JsonResponse($responseData, $statusCode);
+    }
+}
\ No newline at end of file
diff --git a/routes/api-remote.php b/routes/api-remote.php
index 29c8452fa..4f9b4f14b 100644
--- a/routes/api-remote.php
+++ b/routes/api-remote.php
@@ -6,6 +6,7 @@ use Pterodactyl\Http\Controllers\Api\Remote\RusticConfigController;
 use Pterodactyl\Http\Controllers\Api\Remote\SftpAuthenticationController;
 use Pterodactyl\Http\Controllers\Api\Remote\Backups\BackupDeleteController;
 use Pterodactyl\Http\Controllers\Api\Remote\Backups\BackupRemoteUploadController;
+use Pterodactyl\Http\Controllers\Api\Remote\Backups\BackupSizeController;
 use Pterodactyl\Http\Controllers\Api\Remote\Backups\BackupStatusController;
 use Pterodactyl\Http\Controllers\Api\Remote\Servers\ServerDetailsController;
 use Pterodactyl\Http\Controllers\Api\Remote\Servers\ServerInstallController;
@@ -24,6 +25,7 @@ Route::group(['prefix' => '/servers/{uuid}'], function () {
   Route::post('/install', [ServerInstallController::class, 'store']);
 
   Route::get('/rustic-config', [RusticConfigController::class, 'show']);
+  Route::post('/backup-sizes', [BackupSizeController::class, 'update']);
 
   Route::get('/transfer/failure', [ServerTransferController::class, 'failure']);
   Route::get('/transfer/success', [ServerTransferController::class, 'success']);