diff --git a/idaes/core/util/model_statistics.py b/idaes/core/util/model_statistics.py
index 7aacfd2b70..99cb7b315e 100644
--- a/idaes/core/util/model_statistics.py
+++ b/idaes/core/util/model_statistics.py
@@ -403,6 +403,7 @@ def number_grey_box_equalities(block) -> int:
         block, ctype=ExternalGreyBoxBlock, active=True, descend_into=True
     ):
         equalities += len(grey_box.outputs)
+        equalities += grey_box.get_external_model().n_equality_constraints()
     return equalities
 
 
@@ -555,7 +556,7 @@ def deactivated_inequalities_generator(block):
         block : model to be studied
 
     Returns:
-        A generator which returns all in deactivated equality Constraint
+        A generator which returns all deactivated equality Constraint
         components block
     """
     for c in total_inequalities_generator(block):
@@ -1060,22 +1061,78 @@ def unfixed_variables_in_activated_equalities_set(block):
     for v in variables_in_activated_equalities_set(block):
         if not v.fixed:
             var_set.add(v)
-
     # Checks for greyboxes, and if they exist will add
-    # input and output vars to var_set if they are free
-    # inputs and outputs are defined names for greybox class and should always exist
+    for v in unfixed_greybox_variables(block):
+        var_set.add(v)
+    return var_set
+
+
+def unfixed_greybox_variables(block):
+    """
+    Function to return a ComponentSet of all unfixed Var in GreyBoxModels
+
+    Args:
+        block : model to be studied
+
+    Returns:
+        A ComponentSet including all unfixed Var components which appear within
+        activated equality Constraints in block
+    """
+    var_set = ComponentSet()
+    for var in greybox_variables(block):
+        if not var.fixed:
+            var_set.add(var)
+    return var_set
+
+
+def greybox_variables(block):
+    """
+    Function to return a ComponentSet of all Var in GreyBoxModels
+
+    Args:
+        block : model to be studied
+
+    Returns:
+        A ComponentSet including all unfixed Var components which appear within
+        activated equality Constraints in block
+    """
+    var_set = ComponentSet()
     for grey_box in _iter_indexed_block_data_objects(
         block, ctype=ExternalGreyBoxBlock, active=True, descend_into=True
     ):
         for in_var in grey_box.inputs:
-            if not grey_box.inputs[in_var].fixed:
-                var_set.add(grey_box.inputs[in_var])
+            var_set.add(grey_box.inputs[in_var])
         for out_var in grey_box.outputs:
-            if not grey_box.outputs[out_var].fixed:
-                var_set.add(grey_box.outputs[out_var])
+            var_set.add(grey_box.outputs[out_var])
     return var_set
 
 
+def number_of_unfixed_greybox_variables(block):
+    """
+    Function to return a number of unfixed variables in grey box
+    Args:
+        block : model to be studied
+
+    Returns:
+        number of unfixed greybox variables
+    """
+
+    return len(unfixed_greybox_variables(block))
+
+
+def number_of_greybox_variables(block):
+    """
+    Function to return a number of variables in grey box
+    Args:
+        block : model to be studied
+
+    Returns:
+        number of greybox variables
+    """
+
+    return len(greybox_variables(block))
+
+
 def number_unfixed_variables_in_activated_equalities(block):
     """
     Method to return the number of unfixed Var components which appear within
diff --git a/idaes/core/util/tests/test_model_statistics.py b/idaes/core/util/tests/test_model_statistics.py
index 48bce9683c..7085323ea7 100644
--- a/idaes/core/util/tests/test_model_statistics.py
+++ b/idaes/core/util/tests/test_model_statistics.py
@@ -693,7 +693,8 @@ def test_degrees_of_freedom(m):
 def test_degrees_of_freedom_with_graybox():
     """non functional graybox model added to m fixture, to test DOFs
 
-    GreyBoxModel has 3 inputs and 2 outputs calculated an unknown function"""
+    GreyBoxModel has 3 inputs and 2 outputs calculated an unknown function,
+    input a1 and a2 are bound by equality constraint through internal graybox model"""
 
     class BasicGrayBox(ExternalGreyBoxModel):
         def input_names(self):
@@ -702,12 +703,26 @@ def input_names(self):
         def output_names(self):
             return ["o1", "o2"]
 
+        def equality_constraint_names(self):
+            return ["a_sum"]
+
+        def evaluate_equality_constraints(self):
+            a1 = self._input_values[0]
+            a2 = self._input_values[1]
+            return [a1 * 0.5 + a2]
+
     m = ConcreteModel()
 
     m.gb = ExternalGreyBoxBlock(external_model=BasicGrayBox())
+    # test counting functions
+    assert number_of_greybox_variables(m) == 5
+    assert number_of_unfixed_greybox_variables(m) == 5
+    assert number_grey_box_equalities(m) == 3
     # verify DOFS works on stand alone greybox
-    assert degrees_of_freedom(m) == 3
+    assert degrees_of_freedom(m) == 2
     m.gb.inputs.fix()
+    m.gb.inputs["a1"].unfix()
+    assert number_of_unfixed_greybox_variables(m) == 3
     assert degrees_of_freedom(m) == 0
     m.gb.outputs.fix()
     assert degrees_of_freedom(m) == -2
@@ -716,7 +731,7 @@ def output_names(self):
     # verify DOFs works on greybox connected to other vars on a model via constraints
     m.a1 = Var(initialize=1)
     m.a1.fix()
-    m.gb.inputs["a1"].unfix()
+    m.gb.inputs["a2"].unfix()
     m.a1_eq = Constraint(expr=m.a1 == m.gb.inputs["a1"])
     assert degrees_of_freedom(m) == 0
     m.o1 = Var(initialize=1)