diff --git a/app/assets/javascripts/admin/enterprise_fees/directives/ensure_calculator_preferences_match_type.js.coffee b/app/assets/javascripts/admin/enterprise_fees/directives/ensure_calculator_preferences_match_type.js.coffee
index 4376ce59ef..2f4d97c46e 100644
--- a/app/assets/javascripts/admin/enterprise_fees/directives/ensure_calculator_preferences_match_type.js.coffee
+++ b/app/assets/javascripts/admin/enterprise_fees/directives/ensure_calculator_preferences_match_type.js.coffee
@@ -9,9 +9,9 @@ angular.module("admin.enterpriseFees").directive 'spreeEnsureCalculatorPreferenc
       settings = element.parent().parent().find('div.calculator-settings')
       if value == orig_calculator_type
         settings.show()
-        settings.find('input').prop 'disabled', false
+        settings.find('input, select').prop 'disabled', false
       else
         settings.hide()
-        settings.find('input').prop 'disabled', true
+        settings.find('input, select').prop 'disabled', true
       return
     return
diff --git a/app/assets/javascripts/admin/spree/calculator.js b/app/assets/javascripts/admin/spree/calculator.js
index c5dbe0aed0..2dcd074af4 100644
--- a/app/assets/javascripts/admin/spree/calculator.js
+++ b/app/assets/javascripts/admin/spree/calculator.js
@@ -7,11 +7,11 @@ $(function() {
     if (calculator_select.val() === original_calc_type) {
       $('div.calculator-settings').show();
       $('.calculator-settings-warning').hide();
-      $('.calculator-settings').find('input,textarea').prop("disabled", false);
+      $('.calculator-settings').find('input,textarea,select').prop("disabled", false);
     } else {
       $('div.calculator-settings').hide();
       $('.calculator-settings-warning').show();
-      $('.calculator-settings').find('input,textarea').prop("disabled", true);
+      $('.calculator-settings').find('input,textarea,select').prop("disabled", true);
     }
   });
 })
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 139b2b8315..e4f53174d5 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -4212,6 +4212,8 @@ See the %{link} to find out more about %{sitename}'s features and to start using
         spree/payment:
           one: Payment
           other: Payments
+    unit: unit
+    per_unit: per unit
   datetime:
     distance_in_words:
       about_x_hours:
diff --git a/spec/system/admin/enterprise_fees_spec.rb b/spec/system/admin/enterprise_fees_spec.rb
index 680ff8eb50..dbd9a4e2ad 100644
--- a/spec/system/admin/enterprise_fees_spec.rb
+++ b/spec/system/admin/enterprise_fees_spec.rb
@@ -58,42 +58,54 @@ describe '
     expect(page).to have_selector "#sets_enterprise_fee_set_collection_attributes_0_calculator_attributes_preferred_flat_percent[value='12.34']"
   end
 
-  it "editing an enterprise fee" do
+  context "editing an enterprise fee" do
     # Given an enterprise fee
-    fee = create(:enterprise_fee)
-    enterprise = create(:enterprise, name: 'Foo')
+    let!(:fee) { create(:enterprise_fee) }
+    let!(:enterprise) { create(:enterprise, name: 'Foo') }
 
-    # When I go to the enterprise fees page
-    login_as_admin_and_visit admin_enterprise_fees_path
+    before do
+      # When I go to the enterprise fees page
+      login_as_admin_and_visit admin_enterprise_fees_path
+      # And I update the fields for the enterprise fee and click update
+      select 'Foo', from: 'sets_enterprise_fee_set_collection_attributes_0_enterprise_id'
+      select 'Admin', from: 'sets_enterprise_fee_set_collection_attributes_0_fee_type'
+      fill_in 'sets_enterprise_fee_set_collection_attributes_0_name', with: 'Greetings!'
+      select 'Inherit From Product', from: 'sets_enterprise_fee_set_collection_attributes_0_tax_category_id'
+      select 'Flat Percent', from: 'sets_enterprise_fee_set_collection_attributes_0_calculator_type'
+      click_button 'Update'
+    end
 
-    # And I update the fields for the enterprise fee and click update
-    select 'Foo', from: 'sets_enterprise_fee_set_collection_attributes_0_enterprise_id'
-    select 'Admin', from: 'sets_enterprise_fee_set_collection_attributes_0_fee_type'
-    fill_in 'sets_enterprise_fee_set_collection_attributes_0_name', with: 'Greetings!'
-    select 'Inherit From Product',
-           from: 'sets_enterprise_fee_set_collection_attributes_0_tax_category_id'
-    select 'Flat Percent', from: 'sets_enterprise_fee_set_collection_attributes_0_calculator_type'
-    click_button 'Update'
+    it "handle the default cases" do
+      # Then I should see the updated fields for my fee
+      expect(page).to have_select "sets_enterprise_fee_set_collection_attributes_0_enterprise_id",
+                                  selected: 'Foo'
+      expect(page).to have_select "sets_enterprise_fee_set_collection_attributes_0_fee_type",
+                                  selected: 'Admin fee'
+      expect(page).to have_selector "input[value='Greetings!']"
+      expect(page).to have_select 'sets_enterprise_fee_set_collection_attributes_0_tax_category_id',
+                                  selected: 'Inherit From Product'
+      expect(page).to have_selector "option[selected]", text: 'Flat Percent (per item)'
 
-    # Then I should see the updated fields for my fee
-    expect(page).to have_select "sets_enterprise_fee_set_collection_attributes_0_enterprise_id",
-                                selected: 'Foo'
-    expect(page).to have_select "sets_enterprise_fee_set_collection_attributes_0_fee_type",
-                                selected: 'Admin fee'
-    expect(page).to have_selector "input[value='Greetings!']"
-    expect(page).to have_select 'sets_enterprise_fee_set_collection_attributes_0_tax_category_id',
-                                selected: 'Inherit From Product'
-    expect(page).to have_selector "option[selected]", text: 'Flat Percent (per item)'
+      fee.reload
+      expect(fee.enterprise).to eq(enterprise)
+      expect(fee.name).to eq('Greetings!')
+      expect(fee.fee_type).to eq('admin')
+      expect(fee.calculator_type).to eq("Calculator::FlatPercentPerItem")
 
-    fee.reload
-    expect(fee.enterprise).to eq(enterprise)
-    expect(fee.name).to eq('Greetings!')
-    expect(fee.fee_type).to eq('admin')
-    expect(fee.calculator_type).to eq("Calculator::FlatPercentPerItem")
+      # Sets tax_category and inherits_tax_category
+      expect(fee.tax_category).to eq(nil)
+      expect(fee.inherits_tax_category).to eq(true)
+    end
 
-    # Sets tax_category and inherits_tax_category
-    expect(fee.tax_category).to eq(nil)
-    expect(fee.inherits_tax_category).to eq(true)
+    it "handle when updating calculator type for Weight to Flat Rate" do
+      select 'Weight (per kg or lb)', from: 'sets_enterprise_fee_set_collection_attributes_0_calculator_type'
+      click_button 'Update'
+
+      select 'Flat Rate (per item)', from: 'sets_enterprise_fee_set_collection_attributes_0_calculator_type'
+      click_button 'Update'
+
+      expect(fee.reload.calculator_type).to eq("Calculator::PerItem")
+    end
   end
 
   it "deleting an enterprise fee" do
diff --git a/spec/system/admin/shipping_methods_spec.rb b/spec/system/admin/shipping_methods_spec.rb
index 3afb2dc875..b8c7eb2e86 100644
--- a/spec/system/admin/shipping_methods_spec.rb
+++ b/spec/system/admin/shipping_methods_spec.rb
@@ -71,6 +71,18 @@ describe 'shipping methods' do
       expect(page).to have_field "shipping_method_distributor_ids_#{distributor2.id}",
                                  checked: false
     end
+
+    it "handle when updating calculator type for Weight to Flat Rate" do
+      visit spree.edit_admin_shipping_method_path(@shipping_method)
+
+      select2_select 'Weight (per kg or lb)', from: 'calc_type'
+      click_button 'Update'
+
+      select2_select 'Flat Rate (per item)', from: 'calc_type'
+      click_button 'Update'
+
+      expect(@shipping_method.reload.calculator_type).to eq("Calculator::PerItem")
+    end
   end
 
   context "as an enterprise user", js: true do