diff --git a/mediafire_cdxprocessor.py b/mediafire_cdxprocessor.py
index 1ba0a6b..000f126 100644
--- a/mediafire_cdxprocessor.py
+++ b/mediafire_cdxprocessor.py
@@ -22,6 +22,10 @@ def run_cdxsummary(file_path, json_filepath):
         # Add "cdxcount" entry with value 1
         json_output["cdxcount"] = 1
 
+        # Add "cdxsize" entry with the size of the cdx.gz file in bytes
+        cdx_size_bytes = os.path.getsize(file_path)
+        json_output["cdxsize"] = cdx_size_bytes
+
         # Remove "pathquery" and "samples" keys
         if "pathquery" in json_output:
             del json_output["pathquery"]