diff --git a/InvenTree/part/serializers.py b/InvenTree/part/serializers.py
index 9e393724fa..437d6507cb 100644
--- a/InvenTree/part/serializers.py
+++ b/InvenTree/part/serializers.py
@@ -579,7 +579,7 @@ class BomItemSerializer(InvenTreeModelSerializer):
 
     # Annotated fields
     available_stock = serializers.FloatField(read_only=True)
-    substitute_stock = serializers.FloatField(read_only=True)
+    available_substitute_stock = serializers.FloatField(read_only=True)
 
     def __init__(self, *args, **kwargs):
         # part_detail and sub_part_detail serializers are only included if requested.
@@ -636,6 +636,12 @@ class BomItemSerializer(InvenTreeModelSerializer):
         available_stock = total_stock - build_order_allocations - sales_order_allocations
         """
 
+        build_order_filter = Q(build__status__in=BuildStatus.ACTIVE_CODES)
+        sales_order_filter = Q(
+            line__order__status__in=SalesOrderStatus.OPEN,
+            shipment__shipment_date=None,
+        )
+
         # Calculate "total stock" for the referenced sub_part
         # Calculate the "build_order_allocations" for the sub_part
         # Note that these fields are only aliased, not annotated
@@ -651,10 +657,7 @@ class BomItemSerializer(InvenTreeModelSerializer):
             allocated_to_sales_orders=Coalesce(
                 SubquerySum(
                     'sub_part__stock_items__sales_order_allocations__quantity',
-                    filter=Q(
-                        line__order__status__in=SalesOrderStatus.OPEN,
-                        shipment__shipment_date=None,
-                    )
+                    filter=sales_order_filter,
                 ),
                 Decimal(0),
                 output_field=models.DecimalField(),
@@ -662,9 +665,7 @@ class BomItemSerializer(InvenTreeModelSerializer):
             allocated_to_build_orders=Coalesce(
                 SubquerySum(
                     'sub_part__stock_items__allocations__quantity',
-                    filter=Q(
-                        build__status__in=BuildStatus.ACTIVE_CODES,
-                    ),
+                    filter=build_order_filter,
                 ),
                 Decimal(0),
                 output_field=models.DecimalField(),
@@ -680,7 +681,7 @@ class BomItemSerializer(InvenTreeModelSerializer):
         )
 
         # Extract similar information for any 'substitute' parts
-        queryset = queryset.annotate(
+        queryset = queryset.alias(
             substitute_stock=Coalesce(
                 SubquerySum(
                     'substitutes__part__stock_items__quantity',
@@ -688,6 +689,30 @@ class BomItemSerializer(InvenTreeModelSerializer):
                 ),
                 Decimal(0),
                 output_field=models.DecimalField(),
+            ),
+            substitute_build_allocations=Coalesce(
+                SubquerySum(
+                    'substitutes__part__stock_items__allocations__quantity',
+                    filter=build_order_filter,
+                ),
+                Decimal(0),
+                output_field=models.DecimalField(),
+            ),
+            substitute_sales_allocations=Coalesce(
+                SubquerySum(
+                    'substitutes__part__stock_items__sales_order_allocations__quantity',
+                    filter=sales_order_filter,
+                ),
+                Decimal(0),
+                output_field=models.DecimalField(),
+            ),
+        )
+
+        # Calculate 'available_variant_stock' field
+        queryset = queryset.annotate(
+            available_substitute_stock=ExpressionWrapper(
+                F('substitute_stock') - F('substitute_build_allocations') - F('substitute_sales_allocations'),
+                output_field=models.DecimalField(),
             )
         )
 
@@ -765,7 +790,7 @@ class BomItemSerializer(InvenTreeModelSerializer):
 
             # Annotated fields describing available quantity
             'available_stock',
-            'substitute_stock',
+            'available_substitute_stock',
         ]