diff --git a/docs/tuning.md b/docs/tuning.md
index 704778681..26ff1325b 100644
--- a/docs/tuning.md
+++ b/docs/tuning.md
@@ -163,8 +163,8 @@ their work directories), *not* on your driver program.
 **Cache Size Tuning**
 
 One important configuration parameter for GC is the amount of memory that should be used for caching RDDs.
-By default, Spark uses 66% of the configured executor memory (`spark.executor.memory` or `SPARK_MEM`) to
-cache RDDs. This means that 33% of memory is available for any objects created during task execution.
+By default, Spark uses 60% of the configured executor memory (`spark.executor.memory` or `SPARK_MEM`) to
+cache RDDs. This means that 40% of memory is available for any objects created during task execution.
 
 In case your tasks slow down and you find that your JVM is garbage-collecting frequently or running out of
 memory, lowering this value will help reduce the memory consumption. To change this to say 50%, you can call