diff --git a/src/calibre/gui2/preferences/conversion.py b/src/calibre/gui2/preferences/conversion.py
index fb97c7d6c5..26cb062cb2 100644
--- a/src/calibre/gui2/preferences/conversion.py
+++ b/src/calibre/gui2/preferences/conversion.py
@@ -80,8 +80,19 @@ class Base(ConfigWidgetBase):
                 merge_plugin_recs=False)
 
         def widget_factory(cls):
-            return cls(self, self.plumber.get_option_by_name,
-                self.plumber.get_option_help, None, None)
+            plugin = getattr(cls, 'conv_plugin', None)
+            if plugin is None:
+                hfunc = self.plumber.get_option_by_name
+            else:
+                options = plugin.options.union(plugin.common_options)
+
+                def hfunc(name):
+                    for rec in options:
+                        if rec.option == name:
+                            ans = getattr(rec, 'help', None)
+                            if ans is not None:
+                                return ans.replace('%default', str(rec.recommended_value))
+            return cls(self, self.plumber.get_option_by_name, hfunc, None, None)
 
         self.load_conversion_widgets()
         widgets = list(map(widget_factory, self.conversion_widgets))
@@ -131,6 +142,7 @@ class InputOptions(Base):
         for plugin in input_format_plugins():
             pw = config_widget_for_input_plugin(plugin)
             if pw is not None:
+                pw.conv_plugin = plugin
                 self.conversion_widgets.append(pw)
 
 
@@ -144,14 +156,15 @@ class OutputOptions(Base):
                 output_widget = importlib.import_module(
                         'calibre.gui2.convert.'+name)
                 pw = output_widget.PluginWidget
+                pw.conv_plugin = plugin
                 self.conversion_widgets.append(pw)
             except ImportError:
                 continue
 
+
 if __name__ == '__main__':
-    from PyQt5.Qt import QApplication
-    app = QApplication([])
+    from calibre.gui2 import Application
+    app = Application([])
     # test_widget('Conversion', 'Input Options')
     # test_widget('Conversion', 'Common Options')
     test_widget('Conversion', 'Output Options')
-