diff --git a/Doc/library/base64.rst b/Doc/library/base64.rst
index ceecf17cba2..ad9f5f58bee 100644
--- a/Doc/library/base64.rst
+++ b/Doc/library/base64.rst
@@ -218,14 +218,6 @@ The modern interface provides:
    .. versionadded:: 3.4
 
 
-.. note::
-   Both Base85 and Ascii85 have an expansion factor of 5 to 4 (5 Base85 or
-   Ascii85 characters can encode 4 binary bytes), while the better-known
-   Base64 has an expansion factor of 6 to 4.  They are therefore more
-   efficient when space expensive.  They differ by details such as the
-   character map used for encoding.
-
-
 The legacy interface:
 
 .. function:: decode(input, output)