diff --git a/app/schemas.py b/app/schemas.py
index 168faa02c..c7061a5bb 100644
--- a/app/schemas.py
+++ b/app/schemas.py
@@ -308,8 +308,13 @@ class NotificationWithPersonalisationSchema(NotificationWithTemplateSchema):
             renderer=PassThrough()
         )
         in_data['body'] = template.replaced
-        if in_data['template']['template_type'] == 'email':
+        template_type = in_data['template']['template_type']
+        if template_type == 'email':
             in_data['subject'] = template.replaced_subject
+            in_data['content_char_count'] = None
+        else:
+            in_data['content_char_count'] = len(in_data['body'])
+
         in_data.pop('personalisation', None)
         in_data['template'].pop('content', None)
         in_data['template'].pop('subject', None)
diff --git a/tests/app/notifications/test_rest.py b/tests/app/notifications/test_rest.py
index 49813da1b..09fea3219 100644
--- a/tests/app/notifications/test_rest.py
+++ b/tests/app/notifications/test_rest.py
@@ -557,6 +557,7 @@ def test_get_notification_by_id_returns_merged_template_content(notify_db,
             assert response.status_code == 200
             assert notification['body'] == 'Hello world\nYour thing is due soon'
             assert 'subject' not in notification
+            assert notification['content_char_count'] == 34
 
 
 def test_get_notification_by_id_returns_merged_template_content_for_email(
@@ -580,6 +581,7 @@ def test_get_notification_by_id_returns_merged_template_content_for_email(
         assert response.status_code == 200
         assert notification['body'] == 'Hello world\nThis is an email from GOV.UK'
         assert notification['subject'] == 'world'
+        assert notification['content_char_count'] is None
 
 
 def test_get_notifications_for_service_returns_merged_template_content(notify_api,