diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 1f6a8ad11..d966debed 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config --auto-gen-only-exclude`
-# on 2022-10-21 20:17:00 UTC using RuboCop version 1.36.0.
+# on 2022-10-26 21:57:32 UTC using RuboCop version 1.37.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -14,7 +14,7 @@ Layout/LineLength:
   Exclude:
     - 'app/models/druid_version_zip.rb'
 
-# Offense count: 32
+# Offense count: 27
 # Configuration parameters: AllowedMethods, AllowedPatterns, IgnoredMethods.
 Lint/AmbiguousBlockAssociation:
   Exclude:
@@ -23,7 +23,6 @@ Lint/AmbiguousBlockAssociation:
     - 'spec/services/complete_moab_service/shared_examples.rb'
     - 'spec/services/complete_moab_service/update_version_after_validation_spec.rb'
     - 'spec/services/complete_moab_service/update_version_spec.rb'
-    - 'spec/services/shared_examples_complete_moab_handler.rb'
 
 # Offense count: 2
 Lint/MissingSuper:
@@ -34,7 +33,7 @@ Lint/MissingSuper:
 # Offense count: 23
 # Configuration parameters: AllowedMethods, AllowedPatterns, IgnoredMethods, CountRepeatedAttributes.
 Metrics/AbcSize:
-  Max: 66
+  Max: 43
 
 # Offense count: 2
 # Configuration parameters: CountBlocks, Max.
@@ -49,25 +48,23 @@ Metrics/ClassLength:
     - 'app/controllers/objects_controller.rb'
     - 'app/models/druid_version_zip.rb'
 
-# Offense count: 3
+# Offense count: 2
 # Configuration parameters: AllowedMethods, AllowedPatterns, IgnoredMethods, Max.
 Metrics/CyclomaticComplexity:
   Exclude:
-    - 'app/services/complete_moab_service/check_existence.rb'
-    - 'app/services/complete_moab_service/update_version.rb'
+    - 'app/services/audit/catalog_to_archive.rb'
     - 'app/services/complete_moab_service/update_version_after_validation.rb'
 
-# Offense count: 40
+# Offense count: 38
 # Configuration parameters: CountComments, CountAsOne, ExcludedMethods, AllowedMethods, AllowedPatterns, IgnoredMethods.
 Metrics/MethodLength:
   Max: 33
 
-# Offense count: 3
+# Offense count: 2
 # Configuration parameters: AllowedMethods, AllowedPatterns, IgnoredMethods, Max.
 Metrics/PerceivedComplexity:
   Exclude:
-    - 'app/services/complete_moab_service/check_existence.rb'
-    - 'app/services/complete_moab_service/update_version.rb'
+    - 'app/services/audit/catalog_to_archive.rb'
     - 'app/services/complete_moab_service/update_version_after_validation.rb'
 
 # Offense count: 3
@@ -89,7 +86,7 @@ RSpec/InstanceVariable:
   Exclude:
     - 'spec/models/moab_storage_directory_spec.rb'
 
-# Offense count: 378
+# Offense count: 381
 # Configuration parameters: AllowSubject.
 RSpec/MultipleMemoizedHelpers:
   Max: 21
@@ -116,7 +113,7 @@ RSpec/SubjectDeclaration:
     - 'spec/services/reporters/honeybadger_reporter_spec.rb'
     - 'spec/services/reporters/logger_reporter_spec.rb'
 
-# Offense count: 17
+# Offense count: 18
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: slashes, arguments
 Rails/FilePath:
diff --git a/app/models/audit_results.rb b/app/models/audit_results.rb
index 14a36579c..7abb127eb 100644
--- a/app/models/audit_results.rb
+++ b/app/models/audit_results.rb
@@ -32,6 +32,7 @@ class AuditResults
   ZIP_PART_NOT_FOUND = :zip_part_not_found
   ZIP_PARTS_COUNT_DIFFERS_FROM_ACTUAL = :zip_parts_count_differs_from_actual
   ZIP_PARTS_COUNT_INCONSISTENCY = :zip_parts_count_inconsistency
+  ZIP_PARTS_SIZE_INCONSISTENCY = :zip_parts_size_inconsistency
   ZIP_PARTS_NOT_ALL_REPLICATED = :zip_parts_not_all_replicated
   ZIP_PARTS_NOT_CREATED = :zip_parts_not_created
 
@@ -75,6 +76,9 @@ class AuditResults
                                            'number of zip parts rows (%{actual_count})',
     ZIP_PARTS_COUNT_INCONSISTENCY => '%{version} on %{endpoint_name}: ' \
                                      'ZippedMoabVersion has variation in child parts_counts: %{child_parts_counts}',
+    ZIP_PARTS_SIZE_INCONSISTENCY => '%{version} on %{endpoint_name}: ' \
+                                    'Sum of ZippedMoabVersion child part sizes (%{total_part_size}) is less than what is in ' \
+                                    'the Moab: %{moab_version_size}',
     ZIP_PARTS_NOT_ALL_REPLICATED => '%{version} on %{endpoint_name}: not all ' \
                                     'ZippedMoabVersion parts are replicated yet: %{unreplicated_parts_list}',
     ZIP_PARTS_NOT_CREATED => '%{version} on %{endpoint_name}: no zip_parts exist yet for this ZippedMoabVersion'
diff --git a/app/models/druid_version_zip.rb b/app/models/druid_version_zip.rb
index 27669360a..4b6af653d 100644
--- a/app/models/druid_version_zip.rb
+++ b/app/models/druid_version_zip.rb
@@ -166,6 +166,10 @@ def zip_split_size
     '10g'
   end
 
+  def moab_version_size
+    moab_version_files.sum { |f| File.size(f) }
+  end
+
   private
 
   # Throws an error if any of the files in the moab are not yet readable.  For example due to
@@ -192,10 +196,6 @@ def total_part_size
     part_paths.sum { |part_path| File.size(part_path) }
   end
 
-  def moab_version_size
-    moab_version_files.sum { |f| File.size(f) }
-  end
-
   def moab_version_files
     raise "Moab version does not exist: #{moab_version_path}" unless File.exist?(moab_version_path)
     Dir
diff --git a/app/models/preserved_object.rb b/app/models/preserved_object.rb
index 4c723c75f..a2c4b5860 100644
--- a/app/models/preserved_object.rb
+++ b/app/models/preserved_object.rb
@@ -60,6 +60,12 @@ def audit_moab_version_replication!
     MoabReplicationAuditJob.perform_later(self)
   end
 
+  def total_size_of_moab_version(version)
+    return 0 unless complete_moab
+
+    DruidVersionZip.new(druid, version, complete_moab.moab_storage_root.storage_location).moab_version_size
+  end
+
   # Number of PreservedObjects to audit on a daily basis.
   def self.daily_check_count
     PreservedObject.count / (PreservationPolicy.default_policy.fixity_ttl / (60 * 60 * 24))
diff --git a/app/models/zipped_moab_version.rb b/app/models/zipped_moab_version.rb
index d2b6f2320..64f77ea54 100644
--- a/app/models/zipped_moab_version.rb
+++ b/app/models/zipped_moab_version.rb
@@ -6,7 +6,7 @@
 # ZippedMoabVersion objects should be:
 #   preserved_object.current_version * number_of_zip_endpoints_for_preservation_policy
 #
-# @note Does not have size independent of part(s)
+# @note Does not have size independent of part(s), see `#total_part_size`
 class ZippedMoabVersion < ApplicationRecord
   belongs_to :preserved_object, inverse_of: :zipped_moab_versions
   belongs_to :zip_endpoint, inverse_of: :zipped_moab_versions
@@ -37,4 +37,8 @@ def all_parts_replicated?
     # has been created and completely written to disk.  see DruidVersionZip.
     zip_parts.count.positive? && zip_parts.all?(&:ok?)
   end
+
+  def total_part_size
+    zip_parts.sum(&:size)
+  end
 end
diff --git a/app/services/audit/catalog_to_archive.rb b/app/services/audit/catalog_to_archive.rb
index 768d5960c..b50ce7ee0 100644
--- a/app/services/audit/catalog_to_archive.rb
+++ b/app/services/audit/catalog_to_archive.rb
@@ -15,6 +15,15 @@ def self.check_child_zip_part_attributes(zmv, results)
         return false # everything else relies on checking parts, nothing left to do
       end
 
+      total_part_size = zmv.total_part_size
+      moab_version_size = zmv.preserved_object.total_size_of_moab_version(zmv.version)
+      if total_part_size < moab_version_size
+        results.add_result(
+          AuditResults::ZIP_PARTS_SIZE_INCONSISTENCY,
+          base_hash.merge(total_part_size: total_part_size, moab_version_size: moab_version_size)
+        )
+      end
+
       child_parts_counts = zmv.child_parts_counts
       if child_parts_counts.length > 1
         results.add_result(
diff --git a/spec/models/druid_version_zip_spec.rb b/spec/models/druid_version_zip_spec.rb
index 3367cfe97..f08fa015d 100644
--- a/spec/models/druid_version_zip_spec.rb
+++ b/spec/models/druid_version_zip_spec.rb
@@ -101,7 +101,7 @@
     after { FileUtils.rm_rf('/tmp/bj') } # cleanup
 
     context 'when zip size is less than the moab size' do
-      let(:moab_version_size) { dvz.send(:moab_version_size) }
+      let(:moab_version_size) { dvz.moab_version_size }
       let(:total_part_size) { moab_version_size / 2 }
 
       before do
@@ -266,6 +266,14 @@
     end
   end
 
+  describe '#moab_version_size' do
+    let(:dvz) { described_class.new(druid, version, 'spec/fixtures/storage_root01/sdr2objects') }
+
+    it 'returns the sum of all file sizes in a moab version' do
+      expect(dvz.moab_version_size).to eq(1_928_387)
+    end
+  end
+
   describe '#part_keys' do
     let(:druid) { 'dc048cw1328' }
 
diff --git a/spec/models/preserved_object_spec.rb b/spec/models/preserved_object_spec.rb
index a89aec96f..063c21939 100644
--- a/spec/models/preserved_object_spec.rb
+++ b/spec/models/preserved_object_spec.rb
@@ -199,4 +199,39 @@
       expect(described_class.daily_check_count).to eq 11
     end
   end
+
+  describe '#total_size_of_moab_version' do
+    let(:druid) { 'bz514sm9647' }
+    let(:preserved_object) { create(:preserved_object, druid: druid, current_version: current_version) }
+    let(:current_version) { 3 }
+
+    context 'when complete moab is nil' do
+      it 'returns 0' do
+        expect(preserved_object.total_size_of_moab_version(current_version)).to eq(0)
+      end
+    end
+
+    context 'when complete moab exists' do
+      let!(:cm1) { create(:complete_moab, preserved_object: preserved_object, version: current_version, moab_storage_root: msr) } # rubocop:disable RSpec/LetSetup
+
+      context 'when moab version path does not exist' do
+        let(:msr) { create(:moab_storage_root) }
+
+        it 'raises a runtime error' do
+          expect { preserved_object.total_size_of_moab_version(current_version) }.to raise_error(
+            RuntimeError,
+            /Moab version does not exist:/
+          )
+        end
+      end
+
+      context 'when moab version exists' do
+        let(:msr) { MoabStorageRoot.find_by!(storage_location: 'spec/fixtures/storage_root01/sdr2objects') }
+
+        it 'returns the sum of the file sizes' do
+          expect(preserved_object.total_size_of_moab_version(current_version)).to eq(37_989)
+        end
+      end
+    end
+  end
 end
diff --git a/spec/models/zipped_moab_version_spec.rb b/spec/models/zipped_moab_version_spec.rb
index d13844367..d77e64181 100644
--- a/spec/models/zipped_moab_version_spec.rb
+++ b/spec/models/zipped_moab_version_spec.rb
@@ -33,6 +33,31 @@
     end
   end
 
+  describe '#total_part_size' do
+    context 'there are no parts' do
+      it 'returns 0' do
+        expect(zmv.total_part_size).to eq(0)
+      end
+    end
+
+    context 'there are parts' do
+      before do
+        args = attributes_for(:zip_part)
+        zmv.zip_parts.create!(
+          [
+            args.merge(status: 'ok', parts_count: 1, suffix: '.zip', size: 1234),
+            args.merge(status: 'ok', parts_count: 1, suffix: '.z01', size: 1234),
+            args.merge(status: 'ok', parts_count: 1, suffix: '.z02', size: 1234)
+          ]
+        )
+      end
+
+      it 'returns the sum of the part sizes' do
+        expect(zmv.total_part_size).to eq(3702)
+      end
+    end
+  end
+
   describe '#child_parts_counts' do
     context 'there are no parts' do
       it 'returns an empty list' do
diff --git a/spec/services/audit/catalog_to_archive_spec.rb b/spec/services/audit/catalog_to_archive_spec.rb
index 8827429ce..7f3c9c5dc 100644
--- a/spec/services/audit/catalog_to_archive_spec.rb
+++ b/spec/services/audit/catalog_to_archive_spec.rb
@@ -3,7 +3,7 @@
 require 'rails_helper'
 
 RSpec.describe Audit::CatalogToArchive do
-  let(:zmv) { create(:zipped_moab_version) }
+  let(:zmv) { create(:zipped_moab_version, preserved_object: create(:preserved_object_fixture, druid: 'bz514sm9647')) }
   let(:results) { AuditResults.new(druid: zmv.preserved_object.druid, moab_storage_root: zmv.zip_endpoint, check_name: 'CatalogToArchiveSpec') }
   let(:version) { zmv.version }
   let(:endpoint_name) { zmv.zip_endpoint.endpoint_name }
@@ -90,6 +90,27 @@
     end
   end
 
+  context 'when total part size is less than the moab size' do
+    before do
+      args = attributes_for(:zip_part)
+      zmv.zip_parts.create!(
+        [
+          args.merge(status: 'ok', parts_count: 3, suffix: '.zip', size: 111),
+          args.merge(status: 'ok', parts_count: 3, suffix: '.z01', size: 222),
+          args.merge(status: 'ok', parts_count: 3, suffix: '.z02', size: 333)
+        ]
+      )
+    end
+
+    it 'logs the discrepancy' do
+      described_class.check_child_zip_part_attributes(zmv, results)
+      msg = "#{result_prefix}: Sum of ZippedMoabVersion child part sizes (666) is less than what is in the Moab: 202938"
+      expect(results.results).to include(
+        a_hash_including(AuditResults::ZIP_PARTS_SIZE_INCONSISTENCY => msg)
+      )
+    end
+  end
+
   context 'zip parts have been created' do
     context 'some parts are unreplicated' do
       before do