diff --git a/engine/client/vid_common.c b/engine/client/vid_common.c
index d40aebcf..838598cf 100644
--- a/engine/client/vid_common.c
+++ b/engine/client/vid_common.c
@@ -74,6 +74,9 @@ void R_SaveVideoMode( int w, int h, int render_w, int render_h, qboolean maximiz
 	if( refState.width == render_w && refState.height == render_h )
 		return;
 
+	refState.scale_x = (float)render_w / w;
+	refState.scale_y = (float)render_h / h;
+
 	refState.width = render_w;
 	refState.height = render_h;
 
diff --git a/engine/ref_api.h b/engine/ref_api.h
index e71543e0..11f5869e 100644
--- a/engine/ref_api.h
+++ b/engine/ref_api.h
@@ -125,7 +125,7 @@ typedef struct ref_globals_s
 {
 	qboolean developer;
 
-	// viewport width and height
+	// viewport width and height (physical window size)
 	int      width;
 	int      height;
 
@@ -144,6 +144,10 @@ typedef struct ref_globals_s
 	size_t		visbytes;		// cluster size
 
 	int desktopBitsPixel;
+
+	// scaling factor of physical window size compared to logical
+	float scale_x;
+	float scale_y;
 } ref_globals_t;
 
 typedef struct ref_client_s