diff --git a/monai/transforms/spatial/array.py b/monai/transforms/spatial/array.py
index 96d443c193..39d2f0d33f 100644
--- a/monai/transforms/spatial/array.py
+++ b/monai/transforms/spatial/array.py
@@ -1483,12 +1483,13 @@ def __call__(
                 See also: https://pytorch.org/docs/stable/nn.functional.html#grid-sample
         """
         self.randomize()
-        # if not doing transform and spatial size not defined, nothing to do
+        # if not doing transform and spatial size doesn't change, nothing to do
         # except convert to float and convert numpy/torch
-        if not self._do_transform and not spatial_size and not self.spatial_size:
+        sp_size = fall_back_tuple(spatial_size or self.spatial_size, img.shape[1:])
+        do_resampling = self._do_transform or (sp_size != ensure_tuple(img.shape[1:]))
+        if not do_resampling:
             img = img.float() if isinstance(img, torch.Tensor) else img.astype("float32")
             return torch.Tensor(img) if self.resampler.as_tensor_output else np.array(img)
-        sp_size = fall_back_tuple(spatial_size or self.spatial_size, img.shape[1:])
         grid = self.get_identity_grid(sp_size)
         if self._do_transform:
             grid = self.rand_affine_grid(grid=grid)
diff --git a/monai/transforms/spatial/dictionary.py b/monai/transforms/spatial/dictionary.py
index 4a4f039d28..31c8293ecf 100644
--- a/monai/transforms/spatial/dictionary.py
+++ b/monai/transforms/spatial/dictionary.py
@@ -759,7 +759,7 @@ def __call__(
 
         sp_size = fall_back_tuple(self.rand_affine.spatial_size, data[self.keys[0]].shape[1:])
         # change image size or do random transform
-        do_resampling = self.rand_affine.spatial_size is not None or self._do_transform
+        do_resampling = self._do_transform or (sp_size != ensure_tuple(data[self.keys[0]].shape[1:]))
 
         # to be consistent with the self._do_transform case (dtype and device)
         affine = torch.as_tensor(np.eye(len(sp_size) + 1), device=self.rand_affine.rand_affine_grid.device)