diff --git a/torchvision/models/detection/anchor_utils.py b/torchvision/models/detection/anchor_utils.py
index 34fb8d23069..f42c10d8208 100644
--- a/torchvision/models/detection/anchor_utils.py
+++ b/torchvision/models/detection/anchor_utils.py
@@ -213,8 +213,8 @@ def _grid_default_boxes(
         for k, f_k in enumerate(grid_sizes):
             # Now add the default boxes for each width-height pair
             if self.steps is not None:
-                x_f_k = image_size[0] / self.steps[k]
-                y_f_k = image_size[1] / self.steps[k]
+                x_f_k = image_size[1] / self.steps[k]
+                y_f_k = image_size[0] / self.steps[k]
             else:
                 y_f_k, x_f_k = f_k