diff --git a/InvenTree/InvenTree/static/script/inventree/part.js b/InvenTree/InvenTree/static/script/inventree/part.js
index c94c512d6f..693a4d1faa 100644
--- a/InvenTree/InvenTree/static/script/inventree/part.js
+++ b/InvenTree/InvenTree/static/script/inventree/part.js
@@ -181,9 +181,7 @@ function loadPartTable(table, url, options={}) {
         title: 'Stock',
         searchable: false,
         sortable: true,
-        formatter: function(value, row, index, field) {
-            console.log("On order:", row.on_order);
-            
+        formatter: function(value, row, index, field) {            
             var html = "";
             var link = "stock";
 
@@ -198,6 +196,9 @@ function loadPartTable(table, url, options={}) {
             } else if (row.on_order) {
                 value = "<span class='label label-primary'>On Order : " + row.on_order + "</span>";
                 link = "orders";
+            } else if (row.building) {
+                value = "<span class='label label-info'>Building : " + row.building + "</span>";
+                link = "builds";
             } else {
                 value ="<span class='label label-warning'>No Stock</span>";
             }
diff --git a/InvenTree/InvenTree/status_codes.py b/InvenTree/InvenTree/status_codes.py
index e49f9a9824..cbc9f3565f 100644
--- a/InvenTree/InvenTree/status_codes.py
+++ b/InvenTree/InvenTree/status_codes.py
@@ -71,11 +71,17 @@ class StockStatus(StatusCode):
         LOST: _("Lost"),
     }
 
-    # The following codes correspond to parts that are 'available'
+    # The following codes correspond to parts that are 'available' or 'in stock'
     AVAILABLE_CODES = [
         OK,
         ATTENTION,
-        DAMAGED
+        DAMAGED,
+    ]
+
+    # The following codes correspond to parts that are 'unavailable'
+    UNAVAILABLE_CODES = [
+        DESTROYED,
+        LOST,
     ]
 
 
diff --git a/InvenTree/order/tests.py b/InvenTree/order/tests.py
index 351c152472..35cf8909be 100644
--- a/InvenTree/order/tests.py
+++ b/InvenTree/order/tests.py
@@ -130,9 +130,10 @@ class OrderTest(TestCase):
         order.receive_line_item(line, loc, 50, user=None)
 
         line = PurchaseOrderLineItem.objects.get(id=2)
-        order.receive_line_item(line, loc, 2 * line.quantity, user=None)
 
-        self.assertEqual(part.on_order, 1100)
+        order.receive_line_item(line, loc, 500, user=None)
+
+        self.assertEqual(part.on_order, 800)
         self.assertEqual(order.status, OrderStatus.PLACED)
 
         for line in order.pending_line_items():
diff --git a/InvenTree/part/api.py b/InvenTree/part/api.py
index d24f0dc6ee..1d6aaa84aa 100644
--- a/InvenTree/part/api.py
+++ b/InvenTree/part/api.py
@@ -8,7 +8,7 @@ from __future__ import unicode_literals
 from django_filters.rest_framework import DjangoFilterBackend
 from django.conf import settings
 
-from django.db.models import Sum, Count
+from django.db.models import Q, Sum, Count
 
 from rest_framework import status
 from rest_framework.response import Response
@@ -25,6 +25,7 @@ from .models import PartParameter, PartParameterTemplate
 
 from . import serializers as part_serializers
 
+from InvenTree.status_codes import OrderStatus, StockStatus, BuildStatus
 from InvenTree.views import TreeSerializer
 from InvenTree.helpers import str2bool
 
@@ -153,6 +154,18 @@ class PartList(generics.ListCreateAPIView):
 
         queryset = self.filter_queryset(self.get_queryset())
 
+        # Filters for annotations
+
+        # "in_stock" count should only sum stock items which are "in stock"
+        stock_filter = Q(stock_items__status__in=StockStatus.AVAILABLE_CODES)
+
+        # "on_order" items should only sum orders which are currently outstanding
+        order_filter = Q(supplier_parts__purchase_order_line_items__order__status__in=OrderStatus.OPEN)
+
+        # "building" should only reference builds which are active
+        build_filter = Q(builds__status__in=BuildStatus.ACTIVE_CODES)
+
+        # Set of fields we wish to serialize
         data = queryset.values(
             'pk',
             'category',
@@ -171,13 +184,12 @@ class PartList(generics.ListCreateAPIView):
             'salable',
             'active',
         ).annotate(
-            in_stock=Sum('stock_items__quantity'),
-            on_order=Sum('supplier_parts__purchase_order_line_items__quantity'),
+            # Quantity of items which are "in stock"
+            in_stock=Sum('stock_items__quantity', filter=stock_filter),
+            on_order=Sum('supplier_parts__purchase_order_line_items__quantity', filter=order_filter),
+            building=Sum('builds__quantity', filter=build_filter),
         )
 
-        # TODO - Annotate total being built
-        # TODO - Annotate total on order
-
         # Reduce the number of lookups we need to do for the part categories
         categories = {}
 
diff --git a/InvenTree/part/models.py b/InvenTree/part/models.py
index d22e6e7be1..58ee8bbd2c 100644
--- a/InvenTree/part/models.py
+++ b/InvenTree/part/models.py
@@ -569,7 +569,12 @@ class Part(models.Model):
         """ Return the current number of parts currently being built
         """
 
-        return sum([b.quantity for b in self.active_builds])
+        quantity = self.active_builds.aggregate(quantity=Sum('quantity'))['quantity']
+
+        if quantity is None:
+            quantity = 0
+
+        return quantity
 
     @property
     def build_allocation(self):
@@ -919,7 +924,21 @@ class Part(models.Model):
     def on_order(self):
         """ Return the total number of items on order for this part. """
 
-        return sum([part.on_order() for part in self.supplier_parts.all().prefetch_related('purchase_order_line_items')])
+        orders = self.supplier_parts.filter(purchase_order_line_items__order__status__in=OrderStatus.OPEN).aggregate(
+            quantity=Sum('purchase_order_line_items__quantity'),
+            received=Sum('purchase_order_line_items__received')
+        )
+
+        quantity = orders['quantity']
+        received = orders['received']
+
+        if quantity is None:
+            quantity = 0
+
+        if received is None:
+            received = 0
+
+        return quantity - received
 
     def get_parameters(self):
         """ Return all parameters for this part, ordered by name """