diff --git a/README.rst b/README.rst
index 4e48058d..0ed29e0d 100644
--- a/README.rst
+++ b/README.rst
@@ -951,7 +951,7 @@ output_length
     The length of the compressed header block.
 
 percentage_of_original_size
-    ``input_length`` / ``output_length`` * 100
+    ``output_length`` / ``input_length`` * 100
 
 wire
     The compressed header block as a hex string.