diff --git a/app/validators/questions/__init__.py b/app/validators/questions/__init__.py
index 5627387d..45149946 100644
--- a/app/validators/questions/__init__.py
+++ b/app/validators/questions/__init__.py
@@ -10,9 +10,13 @@
 from app.validators.questions.question_validator import QuestionValidator
 
 
-def get_question_validator(question):
+def get_question_validator(question, schema):
+    if question["type"] == "Calculated":
+        validators = {
+            "Calculated": CalculatedQuestionValidator,
+        }
+        return validators.get(question["type"], QuestionValidator)(question, schema)
     validators = {
-        "Calculated": CalculatedQuestionValidator,
         "DateRange": DateRangeQuestionValidator,
         "MutuallyExclusive": MutuallyExclusiveQuestionValidator,
     }
diff --git a/app/validators/questions/calculated_question_validator.py b/app/validators/questions/calculated_question_validator.py
index 7afbc125..3705bc65 100644
--- a/app/validators/questions/calculated_question_validator.py
+++ b/app/validators/questions/calculated_question_validator.py
@@ -1,12 +1,15 @@
 from app.validators.questions.question_validator import QuestionValidator
+from app.validators.routing.types import ANSWER_TYPE_TO_JSON_TYPE, TYPE_NUMBER
 
 
 class CalculatedQuestionValidator(QuestionValidator):
     ANSWER_NOT_IN_QUESTION = "Answer does not exist within this question"
+    ANSWER_TYPE_FOR_CALCULATION_TYPE_INVALID = "Expected the answer type for calculation to be type 'number' but got type '{answer_type}'"
 
     def validate(self):
         super().validate()
         self.validate_calculations()
+        self.validate_calculations_value_source_is_numeric()
         return self.errors
 
     def validate_calculations(self):
@@ -19,3 +22,31 @@ def validate_calculations(self):
             for answer_id in calculation["answers_to_calculate"]:
                 if answer_id not in answer_ids:
                     self.add_error(self.ANSWER_NOT_IN_QUESTION, answer_id=answer_id)
+
+    def _validate_answer_is_numeric(self, answer_id):
+        answer_type = self.schema.get_answer_type(answer_id)
+
+        if ANSWER_TYPE_TO_JSON_TYPE[answer_type.value] != TYPE_NUMBER:
+            self.add_error(
+                self.ANSWER_TYPE_FOR_CALCULATION_TYPE_INVALID.format(
+                    answer_type=ANSWER_TYPE_TO_JSON_TYPE[answer_type.value],
+                ),
+                referenced_answer=answer_id,
+            )
+
+    def validate_calculations_value_source_is_numeric(self):
+        """
+        Validates that source answer is of number type
+        """
+        for calculation in self.question.get("calculations"):
+            value = calculation.get("value")
+
+            if answer_id := calculation.get("answer_id"):
+                self._validate_answer_is_numeric(answer_id)
+
+            elif value and value.get("source"):
+                answer_id = value.get("identifier")
+                # Calculated summary value source is validated elsewhere and must be of a number type
+
+                if value.get("source") == "answers":
+                    self._validate_answer_is_numeric(answer_id)
diff --git a/app/validators/questions/question_validator.py b/app/validators/questions/question_validator.py
index 2d118597..f9235079 100644
--- a/app/validators/questions/question_validator.py
+++ b/app/validators/questions/question_validator.py
@@ -7,11 +7,12 @@ class QuestionValidator(Validator):
     )
     question = {}
 
-    def __init__(self, schema_element):
+    def __init__(self, schema_element, schema=None):
         super().__init__(schema_element)
         self.question = schema_element
         self.answers = self.question.get("answers", [])
         self.context["question_id"] = schema_element["id"]
+        self.schema = schema
 
     def validate(self):
         if self.question["type"] != "MutuallyExclusive":
diff --git a/app/validators/sections/section_validator.py b/app/validators/sections/section_validator.py
index 62d45e6d..e57b8727 100644
--- a/app/validators/sections/section_validator.py
+++ b/app/validators/sections/section_validator.py
@@ -134,7 +134,9 @@ def validate_question(self, block_or_variant):
         question = block_or_variant.get("question")
 
         if question:
-            question_validator = get_question_validator(question)
+            question_validator = get_question_validator(
+                question, self.questionnaire_schema
+            )
 
             self.errors += question_validator.validate()
 
diff --git a/schemas/questions/types/calculated.json b/schemas/questions/types/calculated.json
index a0ef1637..997d6ddb 100644
--- a/schemas/questions/types/calculated.json
+++ b/schemas/questions/types/calculated.json
@@ -43,8 +43,16 @@
               "description": "The id of an answer from which to obtain the total to validate against"
             },
             "value": {
-              "type": "integer",
-              "description": "A hard coded total to validate against"
+              "oneOf": [
+                {
+                  "type": "number",
+                  "description": "A hard coded total to validate against"
+                },
+                {
+                  "$ref": "https://eq.ons.gov.uk/value_sources.json#/value_source_for_calculations",
+                  "description": "A value source to validate against that resolves to a number."
+                }
+              ]
             },
             "answers_to_calculate": {
               "type": "array",
diff --git a/schemas/value_sources.json b/schemas/value_sources.json
index 312a15b8..a93c7421 100644
--- a/schemas/value_sources.json
+++ b/schemas/value_sources.json
@@ -161,5 +161,17 @@
         "$ref": "https://eq.ons.gov.uk/value_sources.json#/list_value_source"
       }
     ]
+  },
+  "value_source_for_calculations": {
+    "description": "Only answer and calculated summary value source are supported in current implementation",
+    "anyOf": [
+      {
+        "$ref": "https://eq.ons.gov.uk/value_sources.json#/answer_value_source",
+        "description": "Only answer types that return numeric answers are valid"
+      },
+      {
+        "$ref": "https://eq.ons.gov.uk/value_sources.json#/calculated_summary_value_source"
+      }
+    ]
   }
 }
diff --git a/tests/schemas/invalid/test_invalid_calculations_value_source.json b/tests/schemas/invalid/test_invalid_calculations_value_source.json
new file mode 100644
index 00000000..e9d6aab5
--- /dev/null
+++ b/tests/schemas/invalid/test_invalid_calculations_value_source.json
@@ -0,0 +1,109 @@
+{
+  "mime_type": "application/json/ons/eq",
+  "language": "en",
+  "schema_version": "0.0.1",
+  "data_version": "0.0.3",
+  "survey_id": "0",
+  "title": "Calculated question with value sources test survey",
+  "theme": "default",
+  "description": "A survey that tests validation against value sources, answer value source is not one of Number types which is expected for calculations",
+  "metadata": [
+    {
+      "name": "user_id",
+      "type": "string"
+    },
+    {
+      "name": "period_id",
+      "type": "string"
+    },
+    {
+      "name": "ru_name",
+      "type": "string"
+    }
+  ],
+  "questionnaire_flow": {
+    "type": "Linear",
+    "options": {
+      "summary": {
+        "collapsible": false
+      }
+    }
+  },
+  "sections": [
+    {
+      "id": "default-section",
+      "groups": [
+        {
+          "id": "group",
+          "title": "Validate sum against answer, calculated summary source",
+          "blocks": [
+            {
+              "type": "Question",
+              "id": "total-block",
+              "question": {
+                "id": "total-question",
+                "title": "Total",
+                "description": [
+                  "Enter a number to breakdown in subsequent questions and calculated summary."
+                ],
+                "type": "General",
+                "answers": [
+                  {
+                    "id": "total-answer",
+                    "label": "Total",
+                    "mandatory": true,
+                    "type": "TextField"
+                  }
+                ]
+              }
+            },
+            {
+              "type": "Question",
+              "id": "breakdown-block",
+              "question": {
+                "id": "breakdown-question",
+                "title": "Breakdown validated against an answer value source",
+                "description": [
+                  "This is a breakdown of the total number from the previous question."
+                ],
+                "type": "Calculated",
+                "calculations": [
+                  {
+                    "calculation_type": "sum",
+                    "value": {
+                      "source": "answers",
+                      "identifier": "total-answer"
+                    },
+                    "answers_to_calculate": [
+                      "breakdown-1",
+                      "breakdown-2",
+                      "breakdown-3",
+                      "breakdown-4"
+                    ],
+                    "conditions": ["equals"]
+                  }
+                ],
+                "answers": [
+                  {
+                    "id": "breakdown-1",
+                    "label": "Breakdown 1",
+                    "mandatory": false,
+                    "decimal_places": 2,
+                    "type": "Number"
+                  },
+                  {
+                    "id": "breakdown-2",
+                    "label": "Breakdown 2",
+                    "mandatory": false,
+                    "decimal_places": 2,
+                    "type": "Number"
+                  }
+                ]
+              }
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}
diff --git a/tests/schemas/valid/test_question_validation_messages.json b/tests/schemas/valid/test_question_validation_messages.json
index a5dac0f3..d2418c28 100644
--- a/tests/schemas/valid/test_question_validation_messages.json
+++ b/tests/schemas/valid/test_question_validation_messages.json
@@ -35,6 +35,31 @@
       "groups": [
         {
           "blocks": [
+            {
+              "type": "Question",
+              "id": "total-block",
+              "question": {
+                "id": "total-question",
+                "title": "Total",
+                "description": [
+                  "Enter a number to breakdown in subsequent questions and calculated summary."
+                ],
+                "type": "General",
+                "answers": [
+                  {
+                    "id": "total-answer",
+                    "label": "Total",
+                    "mandatory": true,
+                    "type": "Number",
+                    "decimal_places": 2,
+                    "minimum": {
+                      "value": 0,
+                      "exclusive": true
+                    }
+                  }
+                ]
+              }
+            },
             {
               "type": "Question",
               "id": "date-block",
diff --git a/tests/validators/blocks/test_calculated_question_validator.py b/tests/validators/blocks/test_calculated_question_validator.py
index b4495947..dc694e23 100644
--- a/tests/validators/blocks/test_calculated_question_validator.py
+++ b/tests/validators/blocks/test_calculated_question_validator.py
@@ -1,42 +1,50 @@
-from app.validators.questions.calculated_question_validator import (
-    CalculatedQuestionValidator,
-)
+from app.validators.questionnaire_schema import QuestionnaireSchema
+from app.validators.questions import get_question_validator
+from tests.test_questionnaire_validator import _open_and_load_schema_file
 
 
 def test_invalid_id_in_answers_to_calculate():
+    filename = "schemas/invalid/test_invalid_calculations_value_source.json"
+    schema = QuestionnaireSchema(_open_and_load_schema_file(filename))
     question = {
-        "answers": [
-            {
-                "decimal_places": 2,
-                "id": "breakdown-1",
-                "label": "Breakdown 1",
-                "type": "Number",
-            },
-            {
-                "decimal_places": 2,
-                "id": "breakdown-2",
-                "label": "Breakdown 2",
-                "type": "Number",
-            },
+        "id": "breakdown-question",
+        "title": "Breakdown validated against an answer value source",
+        "description": [
+            "This is a breakdown of the total number from the previous question."
         ],
+        "type": "Calculated",
         "calculations": [
             {
-                "answer_id": "total-answer",
+                "calculation_type": "sum",
+                "value": {"source": "answers", "identifier": "total-answer"},
                 "answers_to_calculate": [
                     "breakdown-1",
                     "breakdown-2",
                     "breakdown-3",
                     "breakdown-4",
                 ],
-                "calculation_type": "sum",
                 "conditions": ["equals"],
             }
         ],
-        "id": "breakdown-question",
-        "title": "Breakdown",
-        "type": "Calculated",
+        "answers": [
+            {
+                "id": "breakdown-1",
+                "label": "Breakdown 1",
+                "mandatory": False,
+                "decimal_places": 2,
+                "type": "Number",
+            },
+            {
+                "id": "breakdown-2",
+                "label": "Breakdown 2",
+                "mandatory": False,
+                "decimal_places": 2,
+                "type": "Number",
+            },
+        ],
     }
-    validator = CalculatedQuestionValidator(question)
+
+    validator = get_question_validator(question, schema)
     validator.validate()
 
     expected_error_messages = [
@@ -50,6 +58,13 @@ def test_invalid_id_in_answers_to_calculate():
             "question_id": "breakdown-question",
             "answer_id": "breakdown-4",
         },
+        {
+            "message": validator.ANSWER_TYPE_FOR_CALCULATION_TYPE_INVALID.format(
+                answer_type="string"
+            ),
+            "referenced_answer": "total-answer",
+            "question_id": "breakdown-question",
+        },
     ]
 
     assert expected_error_messages == validator.errors
diff --git a/tests/validators/questions/test_question_validator.py b/tests/validators/questions/test_question_validator.py
index 7bf87413..767177e3 100644
--- a/tests/validators/questions/test_question_validator.py
+++ b/tests/validators/questions/test_question_validator.py
@@ -1,4 +1,5 @@
 from app.validators.questions import get_question_validator
+from tests.conftest import get_mock_schema
 
 
 def test_no_answer_label_single_answer():
@@ -9,7 +10,7 @@ def test_no_answer_label_single_answer():
         "answers": [{"id": "number-1", "mandatory": False, "type": "Number"}],
     }
 
-    validator = get_question_validator(question)
+    validator = get_question_validator(question, schema=get_mock_schema())
     validator.validate()
 
     assert not validator.errors
@@ -31,7 +32,7 @@ def test_no_answer_label_multiple_answers():
         ],
     }
 
-    validator = get_question_validator(question)
+    validator = get_question_validator(question, schema=get_mock_schema())
     validator.validate()
 
     expected_error_messages = [
@@ -74,7 +75,7 @@ def test_no_answer_label_mutually_exclusive():
         ],
     }
 
-    validator = get_question_validator(question)
+    validator = get_question_validator(question, schema=get_mock_schema())
     validator.validate()
 
     assert not validator.errors
@@ -106,7 +107,7 @@ def test_no_answer_label_two_answers_last_answer_single_checkbox():
         ],
     }
 
-    validator = get_question_validator(question)
+    validator = get_question_validator(question, schema=get_mock_schema())
     validator.validate()
 
     assert not validator.errors