diff --git a/opentech/apply/review/forms.py b/opentech/apply/review/forms.py
index ba6e382d6030f1df4d5308d4977794c679eb94f8..8cf02101bb616dfda5b29b0131bd99b7f57c314c 100644
--- a/opentech/apply/review/forms.py
+++ b/opentech/apply/review/forms.py
@@ -84,8 +84,10 @@ class ReviewModelForm(StreamBaseForm, forms.ModelForm, metaclass=MixedMetaClass)
 
         for field in self.instance.score_fields:
             score = data.get(field.id)[1]
-            if score != NA:
-                scores.append(score)
+            # Include NA answers as 0.
+            if score == NA:
+                score = 0
+            scores.append(score)
 
         try:
             return sum(scores) / len(scores)
diff --git a/opentech/apply/review/migrations/0020_review_score_calc_update.py b/opentech/apply/review/migrations/0020_review_score_calc_update.py
new file mode 100644
index 0000000000000000000000000000000000000000..a5690797240ee06b3d1b4a371b7ec6a968c163ec
--- /dev/null
+++ b/opentech/apply/review/migrations/0020_review_score_calc_update.py
@@ -0,0 +1,62 @@
+# Generated by Django 2.0.13 on 2019-08-19 11:10
+
+from django.db import migrations
+
+from opentech.apply.review.models import Review
+from opentech.apply.review.options import NA
+
+
+def review_score_update(apps, schema_editor):
+    for review in Review.objects.all():
+        # Disable auto_now on "updated_at" field so date is not changed.
+        for field in review._meta.local_fields:
+            if field.name == 'updated_at':
+                field.auto_now = False
+        # Update the score and save.
+        scores = list()
+        for field in review.score_fields:
+            score = review.form_data.get(field.id)[1]
+            # Include NA answers as 0.
+            if score == NA:
+                score = 0
+            scores.append(score)
+
+        try:
+            review.score = sum(scores) / len(scores)
+        except ZeroDivisionError:
+            review.score = NA
+
+        review.save()
+
+
+def review_score_revert(apps, schema_editor):
+    for review in Review.objects.all():
+        # Disable auto_now on "updated_at" field so date is not changed.
+        for field in review._meta.local_fields:
+            if field.name == 'updated_at':
+                field.auto_now = False
+        # Update the score and save.
+        scores = list()
+        for field in review.score_fields:
+            score = review.form_data.get(field.id)[1]
+            # Exclude NA answers.
+            if score != NA:
+                scores.append(score)
+
+        try:
+            review.score = sum(scores) / len(scores)
+        except ZeroDivisionError:
+            review.score = NA
+
+        review.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('review', '0019_replace_existing_author_field'),
+    ]
+
+    operations = [
+        migrations.RunPython(review_score_update, review_score_revert),
+    ]
diff --git a/opentech/apply/review/tests/test_views.py b/opentech/apply/review/tests/test_views.py
index 7f4614e629916420299604df7885813e6a302073..63eec5e6e9c70ec94e32dac81bb5ac9dce765d3b 100644
--- a/opentech/apply/review/tests/test_views.py
+++ b/opentech/apply/review/tests/test_views.py
@@ -163,20 +163,20 @@ class TestReviewScore(BaseViewTestCase):
         review = self.submit_review_scores()
         self.assertEqual(review.score, NA)
 
-    def test_na_not_included_in_review_average(self):
+    def test_na_included_in_review_average(self):
         review = self.submit_review_scores(NA, 5)
-        self.assertEqual(review.score, 5)
+        self.assertEqual(review.score, 2.5)
 
-    def test_na_not_included_reviews_average(self):
+    def test_na_included_reviews_average(self):
         self.submit_review_scores(NA)
-        self.assertIsNone(Review.objects.score())
+        self.assertIsNotNone(Review.objects.score())
 
-    def test_na_not_included_multiple_reviews_average(self):
+    def test_na_included_multiple_reviews_average(self):
         self.submit_review_scores(NA)
         self.submit_review_scores(5)
 
         self.assertEqual(Review.objects.count(), 2)
-        self.assertEqual(Review.objects.score(), 5)
+        self.assertEqual(Review.objects.score(), 2.5)
 
 
 class UserReviewFormTestCase(BaseViewTestCase):