diff --git a/tests/test_autobatching.py b/tests/test_autobatching.py
index 15640e599..7ec870d3c 100644
--- a/tests/test_autobatching.py
+++ b/tests/test_autobatching.py
@@ -107,6 +107,19 @@ def test_calculate_scaling_metric(si_sim_state: ts.SimState) -> None:
         calculate_memory_scaler(si_sim_state, "invalid_metric")
 
 
+def test_calculate_scaling_metric_non_periodic(benzene_sim_state: ts.SimState) -> None:
+    """Test calculation of scaling metrics for a non-periodic state."""
+    # Test that calculate passes
+    n_atoms_metric = calculate_memory_scaler(benzene_sim_state, "n_atoms")
+    assert n_atoms_metric == benzene_sim_state.n_atoms
+
+    # Test n_atoms_x_density metric works for non-periodic systems
+    n_atoms_x_density_metric = calculate_memory_scaler(
+        benzene_sim_state, "n_atoms_x_density"
+    )
+    assert n_atoms_x_density_metric > 0
+
+
 def test_split_state(si_double_sim_state: ts.SimState) -> None:
     """Test splitting a batched state into individual states."""
     split_states = si_double_sim_state.split()
diff --git a/torch_sim/autobatching.py b/torch_sim/autobatching.py
index cd6fca019..a0cf6aabb 100644
--- a/torch_sim/autobatching.py
+++ b/torch_sim/autobatching.py
@@ -363,7 +363,15 @@ def calculate_memory_scaler(
     if memory_scales_with == "n_atoms":
         return state.n_atoms
     if memory_scales_with == "n_atoms_x_density":
-        volume = torch.abs(torch.linalg.det(state.cell[0])) / 1000
+        if all(state.pbc):
+            volume = torch.abs(torch.linalg.det(state.cell[0])) / 1000
+        else:
+            bbox = state.positions.max(dim=0).values - state.positions.min(dim=0).values
+            # add 2 A in non-periodic directions to account for 2D systems and slabs
+            for i, periodic in enumerate(state.pbc):
+                if not periodic:
+                    bbox[i] += 2.0
+            volume = bbox.prod() / 1000  # convert A^3 to nm^3
         number_density = state.n_atoms / volume.item()
         return state.n_atoms * number_density
     raise ValueError(