diff --git a/ChangeLog b/ChangeLog
index 1f953eaae..edce38a1e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,4 @@
+	* changed semantics of send_buffer_watermark_factor to be specified as a percentage
 	* add incoming_connection_alert for logging all successful incoming connections
 	* feature to encrypt peer connections with a secret AES-256 key stored in .torrent file
 	* deprecated compact storage allocation
diff --git a/docs/manual.rst b/docs/manual.rst
index 23c0e6912..f44cb7714 100644
--- a/docs/manual.rst
+++ b/docs/manual.rst
@@ -4697,10 +4697,12 @@ memory will be wasted. The actual watermark may be lower than this in case
 the upload rate is low, this is the upper limit.
 
 ``send_buffer_watermark_factor`` is multiplied to the peer's upload rate
-to determine the low-watermark for the peer. This is clamped to not
-exceed the ``send_buffer_watermark`` upper limit. This defaults to 1.
-For high capacity connections, setting this higher can improve upload
-performance and disk throughput.
+to determine the low-watermark for the peer. It is specified as a percentage,
+which means 100 represents a factor of 1.
+The low-watermark is still clamped to not exceed the ``send_buffer_watermark``
+upper limit. This defaults to 50. For high capacity connections, setting this
+higher can improve upload performance and disk throughput. Setting it too
+high may waste RAM and create a bias towards read jobs over write jobs.
 
 ``auto_upload_slots`` defaults to true. When true, if there is a global upload
 limit set and the current upload rate is less than 90% of that, another upload
@@ -6950,7 +6952,7 @@ send_buffer_watermark_too_low
 	The number of bytes that we keep outstanding, requested from the disk, is calculated
 	as follows::
 
-		min(512, max(upload_rate * send_buffer_watermark_factor, send_buffer_watermark))
+		min(512, max(upload_rate * send_buffer_watermark_factor / 100, send_buffer_watermark))
 
 	If you receive this alert, you migth want to either increase your ``send_buffer_watermark``
 	or ``send_buffer_watermark_factor``.
diff --git a/include/libtorrent/session_settings.hpp b/include/libtorrent/session_settings.hpp
index fbec8482a..8ad08fc0f 100644
--- a/include/libtorrent/session_settings.hpp
+++ b/include/libtorrent/session_settings.hpp
@@ -136,8 +136,8 @@ namespace libtorrent
 #endif
 			, free_torrent_hashes(true)
 			, upnp_ignore_nonrouters(false)
- 			, send_buffer_watermark(700 * 1024)
-			, send_buffer_watermark_factor(1)
+ 			, send_buffer_watermark(500 * 1024)
+			, send_buffer_watermark_factor(50)
 #ifndef TORRENT_NO_DEPRECATE
 			// deprecated in 0.16
 			, auto_upload_slots(true)
@@ -486,11 +486,12 @@ namespace libtorrent
  		int send_buffer_watermark;
 
 		// the current upload rate to a peer is multiplied by
-		// this factor to get the send buffer watermark. This
-		// product is clamped to the send_buffer_watermark
+		// this factor to get the send buffer watermark. The
+		// factor is specified as a percentage. i.e. 50 -> 0.5
+		// This product is clamped to the send_buffer_watermark
 		// setting to not exceed the max. For high speed
 		// upload, this should be set to a greater value than
-		// 1. The default is 1.
+		// 100. The default is 50.
 		int send_buffer_watermark_factor;
 
 #ifndef TORRENT_NO_DEPRECATE
diff --git a/src/peer_connection.cpp b/src/peer_connection.cpp
index d0a0457a4..6dba97aea 100644
--- a/src/peer_connection.cpp
+++ b/src/peer_connection.cpp
@@ -4354,7 +4354,7 @@ namespace libtorrent
 		int upload_rate = int(m_statistics.upload_rate());
 
 		int buffer_size_watermark = upload_rate
-			* m_ses.settings().send_buffer_watermark_factor;
+			* m_ses.settings().send_buffer_watermark_factor / 100;
 
 		if (buffer_size_watermark < 512) buffer_size_watermark = 512;
 		else if (buffer_size_watermark > m_ses.settings().send_buffer_watermark)
diff --git a/src/session.cpp b/src/session.cpp
index f8c8026cb..1871fb775 100644
--- a/src/session.cpp
+++ b/src/session.cpp
@@ -274,12 +274,12 @@ namespace libtorrent
 		// the bandwidth delay product. Assuming an RTT
 		// of 500 ms, and a send rate of 20 MB/s, the upper
 		// limit should be 10 MB
-		set.send_buffer_watermark = 10 * 1024 * 1024;
+		set.send_buffer_watermark = 2 * 1024 * 1024;
 
-		// put 10 seconds worth of data in the send buffer
+		// put 1.5 seconds worth of data in the send buffer
 		// this gives the disk I/O more heads-up on disk
 		// reads, and can maximize throughput
-		set.send_buffer_watermark_factor = 10;
+		set.send_buffer_watermark_factor = 150;
 
 		// don't retry peers if they fail once. Let them
 		// connect to us if they want to