diff --git a/InvenTree/InvenTree/version.py b/InvenTree/InvenTree/version.py
index 8d9b0e8da1..fe28d780c7 100644
--- a/InvenTree/InvenTree/version.py
+++ b/InvenTree/InvenTree/version.py
@@ -12,11 +12,15 @@ import common.models
 INVENTREE_SW_VERSION = "0.7.0 dev"
 
 # InvenTree API version
-INVENTREE_API_VERSION = 34
+INVENTREE_API_VERSION = 35
 
 """
 Increment this API version number whenever there is a significant change to the API that any clients need to know about
 
+v35 -> 2022-04-01 : https://github.com/inventree/InvenTree/pull/2797
+    - Adds stock allocation information to the Part API
+    - Adds calculated field for "unallocated_quantity"
+
 v34 -> 2022-03-25
     - Change permissions for "plugin list" API endpoint (now allows any authenticated user)
 
diff --git a/InvenTree/part/fixtures/bom.yaml b/InvenTree/part/fixtures/bom.yaml
index e879b8381f..facb7e76ae 100644
--- a/InvenTree/part/fixtures/bom.yaml
+++ b/InvenTree/part/fixtures/bom.yaml
@@ -38,3 +38,11 @@
     part: 1
     sub_part: 5
     quantity: 3
+
+# Make "Assembly" from "Bob"
+- model: part.bomitem
+  pk: 6
+  fields:
+    part: 101
+    sub_part: 100
+    quantity: 10
diff --git a/InvenTree/part/fixtures/part.yaml b/InvenTree/part/fixtures/part.yaml
index 77e808fd7f..d0a2d949b1 100644
--- a/InvenTree/part/fixtures/part.yaml
+++ b/InvenTree/part/fixtures/part.yaml
@@ -108,6 +108,18 @@
     lft: 0
     rght: 0
 
+- model: part.part
+  pk: 101
+  fields:
+    name: 'Assembly'
+    description: 'A high level assembly'
+    salable: true
+    active: True
+    tree_id: 0
+    level: 0
+    lft: 0
+    rght: 0
+
 # A 'template' part
 - model: part.part
   pk: 10000
diff --git a/InvenTree/part/models.py b/InvenTree/part/models.py
index fad0f12e28..c493028d71 100644
--- a/InvenTree/part/models.py
+++ b/InvenTree/part/models.py
@@ -1345,7 +1345,8 @@ class Part(MPTTModel):
 
         queryset = OrderModels.SalesOrderAllocation.objects.filter(item__part__id=self.id)
 
-        pending = kwargs.get('pending', None)
+        # Default behaviour is to only return *pending* allocations
+        pending = kwargs.get('pending', True)
 
         if pending is True:
             # Look only for 'open' orders which have not shipped
@@ -1433,7 +1434,7 @@ class Part(MPTTModel):
         - If this part is a "template" (variants exist) then these are counted too
         """
 
-        return self.get_stock_count()
+        return self.get_stock_count(include_variants=True)
 
     def get_bom_item_filter(self, include_inherited=True):
         """
diff --git a/InvenTree/part/serializers.py b/InvenTree/part/serializers.py
index c46950adca..c352c59eab 100644
--- a/InvenTree/part/serializers.py
+++ b/InvenTree/part/serializers.py
@@ -7,7 +7,7 @@ from decimal import Decimal
 
 from django.urls import reverse_lazy
 from django.db import models, transaction
-from django.db.models import Q
+from django.db.models import ExpressionWrapper, F, Q
 from django.db.models.functions import Coalesce
 from django.utils.translation import ugettext_lazy as _
 
@@ -24,7 +24,10 @@ from InvenTree.serializers import (DataFileUploadSerializer,
                                    InvenTreeAttachmentSerializer,
                                    InvenTreeMoneySerializer)
 
-from InvenTree.status_codes import BuildStatus, PurchaseOrderStatus
+from InvenTree.status_codes import (BuildStatus,
+                                    PurchaseOrderStatus,
+                                    SalesOrderStatus)
+
 from stock.models import StockItem
 
 from .models import (BomItem, BomItemSubstitute,
@@ -363,6 +366,51 @@ class PartSerializer(InvenTreeModelSerializer):
             ),
         )
 
+        """
+        Annotate with the number of stock items allocated to sales orders.
+        This annotation is modeled on Part.sales_order_allocations() method:
+
+        - Only look for "open" orders
+        - Stock items have not been "shipped"
+        """
+        so_allocation_filter = Q(
+            line__order__status__in=SalesOrderStatus.OPEN,  # LineItem points to an OPEN order
+            shipment__shipment_date=None,  # Allocated item has *not* been shipped out
+        )
+
+        queryset = queryset.annotate(
+            allocated_to_sales_orders=Coalesce(
+                SubquerySum('stock_items__sales_order_allocations__quantity', filter=so_allocation_filter),
+                Decimal(0),
+                output_field=models.DecimalField(),
+            )
+        )
+
+        """
+        Annotate with the number of stock items allocated to build orders.
+        This annotation is modeled on Part.build_order_allocations() method
+        """
+        bo_allocation_filter = Q(
+            build__status__in=BuildStatus.ACTIVE_CODES,
+        )
+
+        queryset = queryset.annotate(
+            allocated_to_build_orders=Coalesce(
+                SubquerySum('stock_items__allocations__quantity', filter=bo_allocation_filter),
+                Decimal(0),
+                output_field=models.DecimalField(),
+            )
+        )
+
+        # Annotate with the total 'available stock' quantity
+        # This is the current stock, minus any allocations
+        queryset = queryset.annotate(
+            unallocated_stock=ExpressionWrapper(
+                F('in_stock') - F('allocated_to_sales_orders') - F('allocated_to_build_orders'),
+                output_field=models.DecimalField(),
+            )
+        )
+
         return queryset
 
     def get_starred(self, part):
@@ -376,9 +424,12 @@ class PartSerializer(InvenTreeModelSerializer):
     category_detail = CategorySerializer(source='category', many=False, read_only=True)
 
     # Calculated fields
+    allocated_to_build_orders = serializers.FloatField(read_only=True)
+    allocated_to_sales_orders = serializers.FloatField(read_only=True)
+    unallocated_stock = serializers.FloatField(read_only=True)
+    building = serializers.FloatField(read_only=True)
     in_stock = serializers.FloatField(read_only=True)
     ordering = serializers.FloatField(read_only=True)
-    building = serializers.FloatField(read_only=True)
     stock_item_count = serializers.IntegerField(read_only=True)
     suppliers = serializers.IntegerField(read_only=True)
 
@@ -399,7 +450,8 @@ class PartSerializer(InvenTreeModelSerializer):
         partial = True
         fields = [
             'active',
-
+            'allocated_to_build_orders',
+            'allocated_to_sales_orders',
             'assembly',
             'category',
             'category_detail',
@@ -430,6 +482,7 @@ class PartSerializer(InvenTreeModelSerializer):
             'suppliers',
             'thumbnail',
             'trackable',
+            'unallocated_stock',
             'units',
             'variant_of',
             'virtual',
diff --git a/InvenTree/part/test_api.py b/InvenTree/part/test_api.py
index 23f929bca0..bea7154612 100644
--- a/InvenTree/part/test_api.py
+++ b/InvenTree/part/test_api.py
@@ -9,7 +9,7 @@ from rest_framework import status
 from rest_framework.test import APIClient
 
 from InvenTree.api_tester import InvenTreeAPITestCase
-from InvenTree.status_codes import StockStatus
+from InvenTree.status_codes import BuildStatus, StockStatus
 
 from part.models import Part, PartCategory
 from part.models import BomItem, BomItemSubstitute
@@ -17,6 +17,9 @@ from stock.models import StockItem, StockLocation
 from company.models import Company
 from common.models import InvenTreeSetting
 
+import build.models
+import order.models
+
 
 class PartOptionsAPITest(InvenTreeAPITestCase):
     """
@@ -247,7 +250,7 @@ class PartAPITest(InvenTreeAPITestCase):
         data = {'cascade': True}
         response = self.client.get(url, data, format='json')
         self.assertEqual(response.status_code, status.HTTP_200_OK)
-        self.assertEqual(len(response.data), 13)
+        self.assertEqual(len(response.data), Part.objects.count())
 
     def test_get_parts_by_cat(self):
         url = reverse('api-part-list')
@@ -815,6 +818,10 @@ class PartAPIAggregationTest(InvenTreeAPITestCase):
         'location',
         'bom',
         'test_templates',
+        'build',
+        'location',
+        'stock',
+        'sales_order',
     ]
 
     roles = [
@@ -826,6 +833,9 @@ class PartAPIAggregationTest(InvenTreeAPITestCase):
 
         super().setUp()
 
+        # Ensure the part "variant" tree is correctly structured
+        Part.objects.rebuild()
+
         # Add a new part
         self.part = Part.objects.create(
             name='Banana',
@@ -880,6 +890,153 @@ class PartAPIAggregationTest(InvenTreeAPITestCase):
         self.assertEqual(data['in_stock'], 1100)
         self.assertEqual(data['stock_item_count'], 105)
 
+    def test_allocation_annotations(self):
+        """
+        Tests for query annotations which add allocation information.
+        Ref: https://github.com/inventree/InvenTree/pull/2797
+        """
+
+        # We are looking at Part ID 100 ("Bob")
+        url = reverse('api-part-detail', kwargs={'pk': 100})
+
+        part = Part.objects.get(pk=100)
+
+        response = self.get(url, expected_code=200)
+
+        # Check that the expected annotated fields exist in the data
+        data = response.data
+        self.assertEqual(data['allocated_to_build_orders'], 0)
+        self.assertEqual(data['allocated_to_sales_orders'], 0)
+
+        # The unallocated stock count should equal the 'in stock' coutn
+        in_stock = data['in_stock']
+        self.assertEqual(in_stock, 126)
+        self.assertEqual(data['unallocated_stock'], in_stock)
+
+        # Check that model functions return the same values
+        self.assertEqual(part.build_order_allocation_count(), 0)
+        self.assertEqual(part.sales_order_allocation_count(), 0)
+        self.assertEqual(part.total_stock, in_stock)
+        self.assertEqual(part.available_stock, in_stock)
+
+        # Now, let's create a sales order, and allocate some stock
+        so = order.models.SalesOrder.objects.create(
+            reference='001',
+            customer=Company.objects.get(pk=1),
+        )
+
+        # We wish to send 50 units of "Bob" against this sales order
+        line = order.models.SalesOrderLineItem.objects.create(
+            quantity=50,
+            order=so,
+            part=part,
+        )
+
+        # Create a shipment against the order
+        shipment_1 = order.models.SalesOrderShipment.objects.create(
+            order=so,
+            reference='001',
+        )
+
+        shipment_2 = order.models.SalesOrderShipment.objects.create(
+            order=so,
+            reference='002',
+        )
+
+        # Allocate stock items to this order, against multiple shipments
+        order.models.SalesOrderAllocation.objects.create(
+            line=line,
+            shipment=shipment_1,
+            item=StockItem.objects.get(pk=1007),
+            quantity=17
+        )
+
+        order.models.SalesOrderAllocation.objects.create(
+            line=line,
+            shipment=shipment_1,
+            item=StockItem.objects.get(pk=1008),
+            quantity=18
+        )
+
+        order.models.SalesOrderAllocation.objects.create(
+            line=line,
+            shipment=shipment_2,
+            item=StockItem.objects.get(pk=1006),
+            quantity=15,
+        )
+
+        # Submit the API request again - should show us the sales order allocation
+        data = self.get(url, expected_code=200).data
+
+        self.assertEqual(data['allocated_to_sales_orders'], 50)
+        self.assertEqual(data['in_stock'], 126)
+        self.assertEqual(data['unallocated_stock'], 76)
+
+        # Now, "ship" the first shipment (so the stock is not 'in stock' any more)
+        shipment_1.complete_shipment(None)
+
+        # Refresh the API data
+        data = self.get(url, expected_code=200).data
+
+        self.assertEqual(data['allocated_to_build_orders'], 0)
+        self.assertEqual(data['allocated_to_sales_orders'], 15)
+        self.assertEqual(data['in_stock'], 91)
+        self.assertEqual(data['unallocated_stock'], 76)
+
+        # Next, we create a build order and allocate stock against it
+        bo = build.models.Build.objects.create(
+            part=Part.objects.get(pk=101),
+            quantity=10,
+            title='Making some assemblies',
+            status=BuildStatus.PRODUCTION,
+        )
+
+        bom_item = BomItem.objects.get(pk=6)
+
+        # Allocate multiple stock items against this build order
+        build.models.BuildItem.objects.create(
+            build=bo,
+            bom_item=bom_item,
+            stock_item=StockItem.objects.get(pk=1000),
+            quantity=10,
+        )
+
+        # Request data once more
+        data = self.get(url, expected_code=200).data
+
+        self.assertEqual(data['allocated_to_build_orders'], 10)
+        self.assertEqual(data['allocated_to_sales_orders'], 15)
+        self.assertEqual(data['in_stock'], 91)
+        self.assertEqual(data['unallocated_stock'], 66)
+
+        # Again, check that the direct model functions return the same values
+        self.assertEqual(part.build_order_allocation_count(), 10)
+        self.assertEqual(part.sales_order_allocation_count(), 15)
+        self.assertEqual(part.total_stock, 91)
+        self.assertEqual(part.available_stock, 66)
+
+        # Allocate further stock against the build
+        build.models.BuildItem.objects.create(
+            build=bo,
+            bom_item=bom_item,
+            stock_item=StockItem.objects.get(pk=1001),
+            quantity=10,
+        )
+
+        # Request data once more
+        data = self.get(url, expected_code=200).data
+
+        self.assertEqual(data['allocated_to_build_orders'], 20)
+        self.assertEqual(data['allocated_to_sales_orders'], 15)
+        self.assertEqual(data['in_stock'], 91)
+        self.assertEqual(data['unallocated_stock'], 56)
+
+        # Again, check that the direct model functions return the same values
+        self.assertEqual(part.build_order_allocation_count(), 20)
+        self.assertEqual(part.sales_order_allocation_count(), 15)
+        self.assertEqual(part.total_stock, 91)
+        self.assertEqual(part.available_stock, 56)
+
 
 class BomItemTest(InvenTreeAPITestCase):
     """
diff --git a/InvenTree/part/test_bom_item.py b/InvenTree/part/test_bom_item.py
index 7466277118..88548f3cf7 100644
--- a/InvenTree/part/test_bom_item.py
+++ b/InvenTree/part/test_bom_item.py
@@ -46,7 +46,7 @@ class BomItemTest(TestCase):
     # TODO: Tests for multi-level BOMs
 
     def test_used_in(self):
-        self.assertEqual(self.bob.used_in_count, 0)
+        self.assertEqual(self.bob.used_in_count, 1)
         self.assertEqual(self.orphan.used_in_count, 1)
 
     def test_self_reference(self):
diff --git a/InvenTree/stock/fixtures/stock.yaml b/InvenTree/stock/fixtures/stock.yaml
index 0f44828d8e..2fd5b7eb92 100644
--- a/InvenTree/stock/fixtures/stock.yaml
+++ b/InvenTree/stock/fixtures/stock.yaml
@@ -251,3 +251,104 @@
     rght: 0
     expiry_date: "1990-10-10"
     status: 70
+
+# Multiple stock items for "Bob" (PK 100)
+- model: stock.stockitem
+  pk: 1000
+  fields:
+    part: 100
+    location: 1
+    quantity: 10
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+
+- model: stock.stockitem
+  pk: 1001
+  fields:
+    part: 100
+    location: 1
+    quantity: 11
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+  
+- model: stock.stockitem
+  pk: 1002
+  fields:
+    part: 100
+    location: 1
+    quantity: 12
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+  
+- model: stock.stockitem
+  pk: 1003
+  fields:
+    part: 100
+    location: 1
+    quantity: 13
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+
+- model: stock.stockitem
+  pk: 1004
+  fields:
+    part: 100
+    location: 1
+    quantity: 14
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+  
+- model: stock.stockitem
+  pk: 1005
+  fields:
+    part: 100
+    location: 1
+    quantity: 15
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+  
+- model: stock.stockitem
+  pk: 1006
+  fields:
+    part: 100
+    location: 1
+    quantity: 16
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+  
+- model: stock.stockitem
+  pk: 1007
+  fields:
+    part: 100
+    location: 7
+    quantity: 17
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+  
+- model: stock.stockitem
+  pk: 1008
+  fields:
+    part: 100
+    location: 7
+    quantity: 18
+    level: 0
+    tree_id: 0
+    lft: 0
+    rght: 0
+  
\ No newline at end of file
diff --git a/InvenTree/stock/test_api.py b/InvenTree/stock/test_api.py
index 81973aed31..73bee54110 100644
--- a/InvenTree/stock/test_api.py
+++ b/InvenTree/stock/test_api.py
@@ -104,7 +104,7 @@ class StockItemListTest(StockAPITestCase):
 
         response = self.get_stock()
 
-        self.assertEqual(len(response), 20)
+        self.assertEqual(len(response), 29)
 
     def test_filter_by_part(self):
         """
@@ -113,7 +113,7 @@ class StockItemListTest(StockAPITestCase):
 
         response = self.get_stock(part=25)
 
-        self.assertEqual(len(response), 8)
+        self.assertEqual(len(response), 17)
 
         response = self.get_stock(part=10004)
 
@@ -136,13 +136,13 @@ class StockItemListTest(StockAPITestCase):
         self.assertEqual(len(response), 1)
 
         response = self.get_stock(location=1, cascade=0)
-        self.assertEqual(len(response), 0)
+        self.assertEqual(len(response), 7)
 
         response = self.get_stock(location=1, cascade=1)
-        self.assertEqual(len(response), 2)
+        self.assertEqual(len(response), 9)
 
         response = self.get_stock(location=7)
-        self.assertEqual(len(response), 16)
+        self.assertEqual(len(response), 18)
 
     def test_filter_by_depleted(self):
         """
@@ -153,7 +153,7 @@ class StockItemListTest(StockAPITestCase):
         self.assertEqual(len(response), 1)
 
         response = self.get_stock(depleted=0)
-        self.assertEqual(len(response), 19)
+        self.assertEqual(len(response), 28)
 
     def test_filter_by_in_stock(self):
         """
@@ -161,7 +161,7 @@ class StockItemListTest(StockAPITestCase):
         """
 
         response = self.get_stock(in_stock=1)
-        self.assertEqual(len(response), 17)
+        self.assertEqual(len(response), 26)
 
         response = self.get_stock(in_stock=0)
         self.assertEqual(len(response), 3)
@@ -172,7 +172,7 @@ class StockItemListTest(StockAPITestCase):
         """
 
         codes = {
-            StockStatus.OK: 18,
+            StockStatus.OK: 27,
             StockStatus.DESTROYED: 1,
             StockStatus.LOST: 1,
             StockStatus.DAMAGED: 0,
@@ -205,7 +205,7 @@ class StockItemListTest(StockAPITestCase):
             self.assertIsNotNone(item['serial'])
 
         response = self.get_stock(serialized=0)
-        self.assertEqual(len(response), 8)
+        self.assertEqual(len(response), 17)
 
         for item in response:
             self.assertIsNone(item['serial'])
@@ -217,7 +217,7 @@ class StockItemListTest(StockAPITestCase):
 
         # First, we can assume that the 'stock expiry' feature is disabled
         response = self.get_stock(expired=1)
-        self.assertEqual(len(response), 20)
+        self.assertEqual(len(response), 29)
 
         self.user.is_staff = True
         self.user.save()
@@ -232,7 +232,7 @@ class StockItemListTest(StockAPITestCase):
             self.assertTrue(item['expired'])
 
         response = self.get_stock(expired=0)
-        self.assertEqual(len(response), 19)
+        self.assertEqual(len(response), 28)
 
         for item in response:
             self.assertFalse(item['expired'])
@@ -249,7 +249,7 @@ class StockItemListTest(StockAPITestCase):
         self.assertEqual(len(response), 4)
 
         response = self.get_stock(expired=0)
-        self.assertEqual(len(response), 16)
+        self.assertEqual(len(response), 25)
 
     def test_paginate(self):
         """
@@ -290,7 +290,8 @@ class StockItemListTest(StockAPITestCase):
 
         dataset = self.export_data({})
 
-        self.assertEqual(len(dataset), 20)
+        # Check that *all* stock item objects have been exported
+        self.assertEqual(len(dataset), StockItem.objects.count())
 
         # Expected headers
         headers = [
@@ -308,11 +309,11 @@ class StockItemListTest(StockAPITestCase):
         # Now, add a filter to the results
         dataset = self.export_data({'location': 1})
 
-        self.assertEqual(len(dataset), 2)
+        self.assertEqual(len(dataset), 9)
 
         dataset = self.export_data({'part': 25})
 
-        self.assertEqual(len(dataset), 8)
+        self.assertEqual(len(dataset), 17)
 
 
 class StockItemTest(StockAPITestCase):
diff --git a/InvenTree/stock/tests.py b/InvenTree/stock/tests.py
index 50f77a593b..97639b15bd 100644
--- a/InvenTree/stock/tests.py
+++ b/InvenTree/stock/tests.py
@@ -167,8 +167,8 @@ class StockTest(TestCase):
         self.assertFalse(self.drawer2.has_items())
 
         # Drawer 3 should have three stock items
-        self.assertEqual(self.drawer3.stock_items.count(), 16)
-        self.assertEqual(self.drawer3.item_count, 16)
+        self.assertEqual(self.drawer3.stock_items.count(), 18)
+        self.assertEqual(self.drawer3.item_count, 18)
 
     def test_stock_count(self):
         part = Part.objects.get(pk=1)