diff --git a/lung_cancer_screening/nhsuk_forms/imperial_weight_field.py b/lung_cancer_screening/nhsuk_forms/imperial_weight_field.py
index d8f94702..400534bd 100644
--- a/lung_cancer_screening/nhsuk_forms/imperial_weight_field.py
+++ b/lung_cancer_screening/nhsuk_forms/imperial_weight_field.py
@@ -44,24 +44,31 @@ class ImperialWeightField(forms.MultiValueField):
     def __init__(self, *args, **kwargs):
         error_messages = kwargs.get("error_messages", {})
 
+        bounds_stone_error = "Weight must be between 4 stone and 50 stone"
+
         stone_kwargs = {
             "min_value": 0,
             "max_value": 50,
             "error_messages": {
-                'invalid': 'Stone must be in whole numbers',
-                'min_value': 'Weight must be between 4 stone and 50 stone',
-                'max_value': 'Weight must be between 4 stone and 50 stone',
                 **error_messages,
+                'invalid': 'Stone must be in whole numbers',
+                'min_value': bounds_stone_error,
+                'max_value': bounds_stone_error,
+                'incomplete': "Stone must be between 4 and 50",
             },
         }
+
+        between_pounds = "Pounds must be between 0 and 13"
+
         pounds_kwargs = {
             "min_value": 0,
             "max_value": 13,
             "error_messages": {
-                'invalid': 'Pounds must be in whole numbers',
-                'min_value': 'Pounds must be between 0 and 13',
-                'max_value': 'Pounds must be between 0 and 13',
                 **error_messages,
+                'invalid': 'Pounds must be in whole numbers',
+                'min_value': between_pounds,
+                'max_value': between_pounds,
+                'incomplete': between_pounds,
             },
         }
         fields = (
diff --git a/lung_cancer_screening/questions/forms/imperial_weight_form.py b/lung_cancer_screening/questions/forms/imperial_weight_form.py
index d610d647..14040784 100644
--- a/lung_cancer_screening/questions/forms/imperial_weight_form.py
+++ b/lung_cancer_screening/questions/forms/imperial_weight_form.py
@@ -15,8 +15,7 @@ def __init__(self, *args, **kwargs):
             required=True,
             require_all_fields=False,
             error_messages={
-                'required': 'Enter your weight',
-                'incomplete': 'Enter your weight'
+                'required': 'Enter your weight'
             }
         )
 
diff --git a/lung_cancer_screening/questions/tests/unit/forms/test_imperial_weight_form.py b/lung_cancer_screening/questions/tests/unit/forms/test_imperial_weight_form.py
index 04b0e2a9..798ef5eb 100644
--- a/lung_cancer_screening/questions/tests/unit/forms/test_imperial_weight_form.py
+++ b/lung_cancer_screening/questions/tests/unit/forms/test_imperial_weight_form.py
@@ -47,14 +47,11 @@ def test_setting_weight_imperial_clears_weight_metric(self):
         form.save()
         self.assertEqual(self.response_set.weight_metric, None)
 
-    def test_is_invalid_with_missing_data(self):
+    def test_is_invalid_with_no_values_set(self):
         form = ImperialWeightForm(
             participant=self.participant,
             instance=self.response_set,
-            data={
-                "weight_imperial_0": "5",
-                # missing pounds
-            }
+            data={}
         )
         self.assertFalse(form.is_valid())
         self.assertEqual(
@@ -62,6 +59,7 @@ def test_is_invalid_with_missing_data(self):
             ["Enter your weight"]
         )
 
+
     def test_is_invalid_when_given_a_decimal_stone_value(self):
         form = ImperialWeightForm(
             participant=self.participant,
@@ -76,3 +74,93 @@ def test_is_invalid_when_given_a_decimal_stone_value(self):
             form.errors["weight_imperial"],
             ["Stone must be in whole numbers"]
         )
+
+    def test_is_invalid_with_missing_pounds(self):
+        form = ImperialWeightForm(
+            participant=self.participant,
+            instance=self.response_set,
+            data={
+                "weight_imperial_0": "5",
+                # missing pounds
+            }
+        )
+        self.assertFalse(form.is_valid())
+        self.assertEqual(
+            form.errors["weight_imperial"],
+            ["Pounds must be between 0 and 13"]
+        )
+
+    def test_is_invalid_with_missing_stone(self):
+        form = ImperialWeightForm(
+            participant=self.participant,
+            instance=self.response_set,
+            data={
+                # missing stone
+                "weight_imperial_1": "5"
+            }
+        )
+        self.assertFalse(form.is_valid())
+        self.assertEqual(
+            form.errors["weight_imperial"],
+            ["Stone must be between 4 and 50"]
+        )
+
+    def test_is_invalid_when_pounds_under_0(self):
+        form = ImperialWeightForm(
+            participant=self.participant,
+            instance=self.response_set,
+            data={
+                "weight_imperial_0": "5",
+                "weight_imperial_1": "-1"
+            }
+        )
+        self.assertFalse(form.is_valid())
+        self.assertEqual(
+            form.errors["weight_imperial"],
+            ["Pounds must be between 0 and 13"]
+        )
+
+    def test_is_invalid_when_pounds_over_13(self):
+        form = ImperialWeightForm(
+            participant=self.participant,
+            instance=self.response_set,
+            data={
+                "weight_imperial_0": "5",
+                "weight_imperial_1": "14"
+            }
+        )
+        self.assertFalse(form.is_valid())
+        self.assertEqual(
+            form.errors["weight_imperial"],
+            ["Pounds must be between 0 and 13"]
+        )
+
+    def test_is_invalid_when_stone_under_4(self):
+        form = ImperialWeightForm(
+            participant=self.participant,
+            instance=self.response_set,
+            data={
+                "weight_imperial_0": "3",
+                "weight_imperial_1": "10"
+            }
+        )
+        self.assertFalse(form.is_valid())
+        self.assertEqual(
+            form.errors["weight_imperial"],
+            ["Weight must be between 4 stone and 50 stone"]
+        )
+
+    def test_is_invalid_when_stone_over_50(self):
+        form = ImperialWeightForm(
+            participant=self.participant,
+            instance=self.response_set,
+            data={
+                "weight_imperial_0": "51",
+                "weight_imperial_1": "0"
+            }
+        )
+        self.assertFalse(form.is_valid())
+        self.assertEqual(
+            form.errors["weight_imperial"],
+            ["Weight must be between 4 stone and 50 stone"]
+        )