diff --git a/res/values/strings.xml b/res/values/strings.xml
index 8b07688641..e2b673f83b 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -506,6 +506,14 @@
     <string name="MediaOverviewActivity_List_view_description">List view</string>
     <string name="MediaOverviewActivity_Selected_description">Selected</string>
 
+    <plurals name="MediaOverviewActivity_d_items_s">
+        <item quantity="one">%1$d item %2$s</item>
+        <item quantity="other">%1$d items %2$s</item>
+    </plurals>
+    <plurals name="MediaOverviewActivity_d_items">
+        <item quantity="one">%1$d item</item>
+        <item quantity="other">%1$d items</item>
+    </plurals>
     <string name="MediaOverviewActivity_file">File</string>
     <string name="MediaOverviewActivity_audio">Audio</string>
     <string name="MediaOverviewActivity_video">Video</string>
diff --git a/src/org/thoughtcrime/securesms/mediaoverview/MediaGalleryAllAdapter.java b/src/org/thoughtcrime/securesms/mediaoverview/MediaGalleryAllAdapter.java
index 45fdd431cc..1a395e3d29 100644
--- a/src/org/thoughtcrime/securesms/mediaoverview/MediaGalleryAllAdapter.java
+++ b/src/org/thoughtcrime/securesms/mediaoverview/MediaGalleryAllAdapter.java
@@ -27,6 +27,8 @@ import androidx.annotation.NonNull;
 import androidx.lifecycle.Observer;
 import androidx.recyclerview.widget.RecyclerView;
 
+import com.annimon.stream.Collectors;
+import com.annimon.stream.Stream;
 import com.codewaves.stickyheadergrid.StickyHeaderGridAdapter;
 
 import org.thoughtcrime.securesms.R;
@@ -187,6 +189,12 @@ final class MediaGalleryAllAdapter extends StickyHeaderGridAdapter {
     return selected.size();
   }
 
+  public long getSelectedMediaTotalFileSize() {
+    //noinspection ConstantConditions attacment cannot be null if selected
+    return Stream.of(selected.values())
+                 .collect(Collectors.summingLong(a -> a.getAttachment().getSize()));
+  }
+
   @NonNull
   public Collection<MediaRecord> getSelectedMedia() {
     return new HashSet<>(selected.values());
diff --git a/src/org/thoughtcrime/securesms/mediaoverview/MediaOverviewPageFragment.java b/src/org/thoughtcrime/securesms/mediaoverview/MediaOverviewPageFragment.java
index 0e669d48f1..03dd4350d3 100644
--- a/src/org/thoughtcrime/securesms/mediaoverview/MediaOverviewPageFragment.java
+++ b/src/org/thoughtcrime/securesms/mediaoverview/MediaOverviewPageFragment.java
@@ -37,6 +37,7 @@ import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mms.GlideApp;
 import org.thoughtcrime.securesms.mms.PartAuthority;
 import org.thoughtcrime.securesms.util.MediaUtil;
+import org.thoughtcrime.securesms.util.Util;
 
 public final class MediaOverviewPageFragment extends Fragment
   implements MediaGalleryAllAdapter.ItemClickListener,
@@ -117,6 +118,7 @@ public final class MediaOverviewPageFragment extends Fragment
           this.sorting = sorting;
           adapter.setShowFileSizes(sorting.isRelatedToFileSize());
           LoaderManager.getInstance(this).restartLoader(0, null, this);
+          refreshActionModeTitle();
         }
       });
 
@@ -134,6 +136,7 @@ public final class MediaOverviewPageFragment extends Fragment
     this.detail = detail;
     adapter.setDetailView(detail);
     refreshLayoutManager();
+    refreshActionModeTitle();
   }
 
   @Override
@@ -202,7 +205,7 @@ public final class MediaOverviewPageFragment extends Fragment
     if (adapter.getSelectedMediaCount() == 0) {
       actionMode.finish();
     } else {
-      actionMode.setTitle(String.valueOf(adapter.getSelectedMediaCount()));
+      refreshActionModeTitle();
     }
   }
 
@@ -263,7 +266,33 @@ public final class MediaOverviewPageFragment extends Fragment
 
   private void handleSelectAllMedia() {
     getListAdapter().selectAllMedia();
-    actionMode.setTitle(String.valueOf(getListAdapter().getSelectedMediaCount()));
+    refreshActionModeTitle();
+  }
+
+  private void refreshActionModeTitle() {
+    if (actionMode != null) {
+      actionMode.setTitle(getActionModeTitle());
+    }
+  }
+
+  private String getActionModeTitle() {
+    MediaGalleryAllAdapter adapter           = getListAdapter();
+    int                    mediaCount        = adapter.getSelectedMediaCount();
+    boolean                showTotalFileSize = detail                                     ||
+                                               mediaType != MediaLoader.MediaType.GALLERY ||
+                                               sorting   == MediaDatabase.Sorting.Largest;
+
+    if (showTotalFileSize) {
+      long                   totalFileSize = adapter.getSelectedMediaTotalFileSize();
+      return getResources().getQuantityString(R.plurals.MediaOverviewActivity_d_items_s,
+                                            mediaCount,
+                                            mediaCount,
+                                            Util.getPrettyFileSize(totalFileSize));
+    } else {
+      return getResources().getQuantityString(R.plurals.MediaOverviewActivity_d_items,
+                                            mediaCount,
+                                            mediaCount);
+    }
   }
 
   private MediaGalleryAllAdapter getListAdapter() {
@@ -283,7 +312,7 @@ public final class MediaOverviewPageFragment extends Fragment
     @Override
     public boolean onCreateActionMode(ActionMode mode, Menu menu) {
       mode.getMenuInflater().inflate(R.menu.media_overview_context, menu);
-      mode.setTitle("1");
+      refreshActionModeTitle();
 
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
         Window window = requireActivity().getWindow();