diff --git a/include/map.h b/include/map.h
index ed57b68..49fff07 100644
--- a/include/map.h
+++ b/include/map.h
@@ -33,6 +33,10 @@ typedef struct map_t {
 } map_t;
 
 
+// calculates width in pixels of one block in the SDL window according to currently loaded map and configured window size and updates the config.
+void updateBlockSizePx();
+
+
 // search and load map by name in storedMaps[] (map.c) 
 // stops program when map not found!
 void loadMapByName(char *name);
diff --git a/src/config.c b/src/config.c
index 658f531..e9d61a6 100644
--- a/src/config.c
+++ b/src/config.c
@@ -1,4 +1,12 @@
 #include "config.h"
 
-//global config struct
-config_t config;
\ No newline at end of file
+//define global struct for configuration values
+//default values defined here: (note: gets modified by map.c or menu.c)
+config_t config = {
+    .windowSize = 800,
+    .blockSizePx = 800/10, //default map is 10x10 blocks
+    .cycleDurationMs = 300,
+    .difficulty = 1,
+    .snakeDefaultLength = 2,
+    .leaderboardFilename = ""
+};
\ No newline at end of file
diff --git a/src/map.c b/src/map.c
index 222b506..13eec17 100644
--- a/src/map.c
+++ b/src/map.c
@@ -105,6 +105,24 @@ map_t generateMap(int difficulty, int sizeX, int sizeY)
 
 
 
+//===========================
+//==== updateBlockSizePx ====
+//===========================
+// calculates width in pixels of one block in the SDL window according to currently loaded map and configured window size and updates the config.
+void updateBlockSizePx(){
+    // due to square pixel requirement
+    // larger dimension of the map has to be used if map is not square
+    if (game.map.height >= game.map.width) {
+        config.blockSizePx = config.windowSize / game.map.height;
+    }
+    else
+    {
+        config.blockSizePx = config.windowSize / game.map.width;
+    }
+}
+
+
+
 //===========================
 //====== loadMapByName ======
 //===========================
@@ -142,6 +160,8 @@ void loadMap(map_t map)
     printMap(map);
 #endif
     game.map = map;
+    // update rendered pixel size (due to new map size)
+    updateBlockSizePx();
     game.mapIsLoaded = true;
     return;
 }