diff --git a/src/calibre/manual/faq.rst b/src/calibre/manual/faq.rst
index f6e293013e..a6d1467cab 100644
--- a/src/calibre/manual/faq.rst
+++ b/src/calibre/manual/faq.rst
@@ -29,6 +29,7 @@ It can convert every input format in the following list, to every output format.
     PRC is a generic format, |app| supports PRC files with TextRead and MOBIBook headers.
     PDB is also a generic format. |app| supports eReder, Plucker, PML and zTxt PDB files.
     DJVU support is only for converting DJVU files that contain embedded text. These are typically generated by OCR software.
+    MOBI books can be of two types Mobi6 and KF8. |app| currently fully supports Mobi6 and supports conversion from, but not to, KF8
 
 .. _best-source-formats: