diff --git a/app/models/attachment.rb b/app/models/attachment.rb
index 2a8e575f3..4fa1b7e57 100644
--- a/app/models/attachment.rb
+++ b/app/models/attachment.rb
@@ -68,7 +68,8 @@ class Attachment < ApplicationRecord
     {
       extension: extension,
       data_url: file_url,
-      thumb_url: thumb_url
+      thumb_url: thumb_url,
+      file_size: file.byte_size
     }
   end