diff --git a/include/etl/bit_stream.h b/include/etl/bit_stream.h
index 23b82dbf..6475ce3e 100644
--- a/include/etl/bit_stream.h
+++ b/include/etl/bit_stream.h
@@ -1198,13 +1198,21 @@ namespace etl
     }
 
     //***************************************************************************
-    /// Returns the number of bytes used in the stream.
+    /// Returns the number of bytes in the stream buffer.
     //***************************************************************************
     size_t size_bytes() const
     {
       return length_chars;
     }
 
+    //***************************************************************************
+    /// Returns the number of bits in the stream buffer.
+    //***************************************************************************
+    size_t size_bits() const
+    {
+      return length_chars * CHAR_BIT;
+    }
+
     //***************************************************************************
     /// Returns start of the stream.
     //***************************************************************************