diff --git a/README.md b/README.md
index 3747930..2096cc1 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,8 @@ Execute as:
 
     ./ds N PREFIX
 
-Where N is a positive integer greater than zero and PREFIX is a string to append to the output file names.
+Where N is a positive integer greater than zero and PREFIX is a string to append to the output file names. The generated island
+will be of size (2^n + 1)x(2^n + 1).
 
 The diamond-square mid point displacement implementation is a port of the code outlined in [this post] [1] at Stack Overflow.