diff --git a/src/calibre/gui2/convert/bulk.py b/src/calibre/gui2/convert/bulk.py
index 520def5b6b..6496f460aa 100644
--- a/src/calibre/gui2/convert/bulk.py
+++ b/src/calibre/gui2/convert/bulk.py
@@ -105,6 +105,7 @@ class BulkConfig(Config):
         for w in widgets:
             w.set_help_signal.connect(self.help.setPlainText)
             w.setVisible(False)
+            w.layout().setContentsMargins(0, 0, 0, 0)
 
         self._groups_model = GroupModel(widgets)
         self.groups.setModel(self._groups_model)
diff --git a/src/calibre/gui2/convert/heuristics.ui b/src/calibre/gui2/convert/heuristics.ui
index 2d7cae9b60..ea65fc2f5b 100644
--- a/src/calibre/gui2/convert/heuristics.ui
+++ b/src/calibre/gui2/convert/heuristics.ui
@@ -213,6 +213,19 @@
      </layout>
     </widget>
    </item>
+   <item>
+    <spacer name="verticalSpacer">
+     <property name="orientation">
+      <enum>Qt::Vertical</enum>
+     </property>
+     <property name="sizeHint" stdset="0">
+      <size>
+       <width>20</width>
+       <height>40</height>
+      </size>
+     </property>
+    </spacer>
+   </item>
   </layout>
  </widget>
  <resources/>
diff --git a/src/calibre/gui2/convert/single.py b/src/calibre/gui2/convert/single.py
index 4f27cce81f..1be8860d42 100644
--- a/src/calibre/gui2/convert/single.py
+++ b/src/calibre/gui2/convert/single.py
@@ -240,6 +240,7 @@ class Config(QDialog):
         for w in widgets:
             w.set_help_signal.connect(self.help.setPlainText)
             w.setVisible(False)
+            w.layout().setContentsMargins(0, 0, 0, 0)
 
         self._groups_model = GroupModel(widgets)
         self.groups.setModel(self._groups_model)
diff --git a/src/calibre/gui2/preferences/conversion.py b/src/calibre/gui2/preferences/conversion.py
index 4282ef7bf2..e056f67426 100644
--- a/src/calibre/gui2/preferences/conversion.py
+++ b/src/calibre/gui2/preferences/conversion.py
@@ -101,6 +101,7 @@ class Base(ConfigWidgetBase):
 
         for w in widgets:
             w.changed_signal.connect(self.changed_signal)
+            w.layout().setContentsMargins(6, 6, 6, 6)
             sa = QScrollArea(self)
             sa.setWidget(w)
             sa.setWidgetResizable(True)