getting the unity terrain brush size

gistfile1.cs

// to get the terrain brush size in an editor script
EditorPrefs.GetInt("TerrainBrushSize")

// if you need to get the terrain brush size from a non-editor script (monobehaviour)
System.Type editorPrefs = System.Type.GetType("UnityEditor.EditorPrefs, UnityEditor", false, false);
System.Type[] paramTypes = new System.Type[]{ typeof(string) };
System.Reflection.MethodInfo method = editorPrefs.GetMethod(
	"GetInt", 
	BindingFlags.Public | BindingFlags.Static,
	null,
	paramTypes,
	null
);
int terrainBrushSize = (int)method.Invoke(null, new string[]{"TerrainBrushSize"});