diff --git a/frigate/camera/state.py b/frigate/camera/state.py
index f04a59d298..0a070cf48b 100644
--- a/frigate/camera/state.py
+++ b/frigate/camera/state.py
@@ -134,10 +134,8 @@ class CameraState:
                         and self.camera_config.detect.width is not None
                         and self.camera_config.detect.height is not None
                     ):
-                        max_target_box = (
-                            self.ptz_autotracker_thread.tracked_object_metrics[
-                                self.name
-                            ]["max_target_box"]
+                        max_target_box = self.ptz_autotracker_thread.max_target_box(
+                            self.name
                         )
                         side_length = max_target_box * (
                             max(
diff --git a/frigate/ptz/autotrack.py b/frigate/ptz/autotrack.py
index c04bd77fc8..3997f64551 100644
--- a/frigate/ptz/autotrack.py
+++ b/frigate/ptz/autotrack.py
@@ -332,6 +332,11 @@ class PtzAutoTracker(threading.Thread):
     def _reset_tracked_object_metrics(self, camera: str) -> None:
         self.tracked_object_metrics[camera] = {}
 
+    def max_target_box(self, camera: str) -> float:
+        """Return the largest target box ratio allowed for the zoom factor."""
+        zoom_factor = self.config.cameras[camera].onvif.autotracking.zoom_factor
+        return AUTOTRACKING_MAX_AREA_RATIO ** (1 / zoom_factor)
+
     async def _wait_until_stopped(
         self, camera: str, metrics: PTZMetrics | None = None
     ) -> None:
@@ -940,7 +945,7 @@ class PtzAutoTracker(threading.Thread):
         camera_config = self.config.cameras[camera]
         tom = self.tracked_object_metrics[camera]
         zoom_factor = camera_config.onvif.autotracking.zoom_factor
-        max_target_box = AUTOTRACKING_MAX_AREA_RATIO ** (1 / zoom_factor)
+        max_target_box = self.max_target_box(camera)
         camera_width = camera_config.frame_shape[1]
         camera_height = camera_config.frame_shape[0]
         camera_fps = camera_config.detect.fps
@@ -1174,7 +1179,7 @@ class PtzAutoTracker(threading.Thread):
         camera_config = self.config.cameras[camera]
         tom = self.tracked_object_metrics[camera]
         zoom_factor = camera_config.onvif.autotracking.zoom_factor
-        max_target_box = AUTOTRACKING_MAX_AREA_RATIO ** (1 / zoom_factor)
+        max_target_box = self.max_target_box(camera)
 
         # frame width and height
         camera_width = camera_config.frame_shape[1]
diff --git a/frigate/test/test_ptz_autotrack.py b/frigate/test/test_ptz_autotrack.py
index 78b0aa0c78..f93f9e367c 100644
--- a/frigate/test/test_ptz_autotrack.py
+++ b/frigate/test/test_ptz_autotrack.py
@@ -123,5 +123,19 @@ class TestAutotrackerDisable(unittest.TestCase):
         self.assertIs(payload, autotracking)
 
 
+class TestAutotrackerMaxTargetBox(unittest.TestCase):
+    def test_follows_live_zoom_factor(self) -> None:
+        # the debug overlay and the zoom decisions both read this, so it has to
+        # track a zoom_factor changed while an object is being followed
+        tracker = _make_tracker()
+        autotracking = tracker.config.cameras[CAMERA].onvif.autotracking
+
+        autotracking.zoom_factor = 0.5
+        self.assertAlmostEqual(tracker.max_target_box(CAMERA), 0.6**2)
+
+        autotracking.zoom_factor = 0.25
+        self.assertAlmostEqual(tracker.max_target_box(CAMERA), 0.6**4)
+
+
 if __name__ == "__main__":
     unittest.main()