Index: lcl/include/application.inc
===================================================================
--- lcl/include/application.inc	(revision 54435)
+++ lcl/include/application.inc	(working copy)
@@ -437,6 +437,14 @@
     raise Exception.Create(rsNoWidgetSet);
   end;
   WidgetSet.AppInit(ScreenInfo);
+  {$IFDEF DARWIN}
+  // Mac OSX (all WS) return 72 PPI for 100% scaling.
+  // The LCL needs 96 PPI for correct
+  //   a) font size scaling (Height/Size ratio)
+  //   b) High-DPI scaling (Application.Scaled)
+  ScreenInfo.PixelsPerInchX := MulDiv(ScreenInfo.PixelsPerInchX, 96, 72);
+  ScreenInfo.PixelsPerInchY := MulDiv(ScreenInfo.PixelsPerInchY, 96, 72);
+  {$ENDIF}
   ScreenInfo.Initialized := True;
   Screen.UpdateScreen;
   // set that we are initialized => all exceptions will be handled by our HandleException
Index: lcl/interfaces/carbon/carbonwinapi.inc
===================================================================
--- lcl/interfaces/carbon/carbonwinapi.inc	(revision 54435)
+++ lcl/interfaces/carbon/carbonwinapi.inc	(working copy)
@@ -1455,8 +1455,8 @@
   case Index of
   LOGPIXELSX,
   LOGPIXELSY:
-    // logical is always 96 dpi (to correspond with 100% scaling on Windows), although physical can differ
-    Result := 96;
+    // logical is allways 72 dpi, although physical can differ
+    Result := 72; // TODO: test scaling and magnification
   BITSPIXEL:  Result := CGDisplayBitsPerPixel(CGMainDisplayID);
   else
     DebugLn('TCarbonWidgetSet.GetDeviceCaps TODO Index: ' + DbgS(Index));
Index: lcl/interfaces/cocoa/cocoawinapi.inc
===================================================================
--- lcl/interfaces/cocoa/cocoawinapi.inc	(revision 54435)
+++ lcl/interfaces/cocoa/cocoawinapi.inc	(working copy)
@@ -1875,9 +1875,9 @@
   // todo: change implementation for printers
   case Index of
     HORZSIZE:
-      Result := Round(NSScreen.mainScreen.frame.size.width / 96 * 25.4);
+      Result := Round(NSScreen.mainScreen.frame.size.width / 72 * 25.4);
     VERTSIZE:
-      Result := Round(NSScreen.mainScreen.frame.size.height / 96 * 25.4);
+      Result := Round(NSScreen.mainScreen.frame.size.height / 72 * 25.4);
     HORZRES:
       Result := Round(NSScreen.mainScreen.frame.size.width);
     BITSPIXEL:
@@ -1887,9 +1887,9 @@
     SIZEPALETTE:
       Result := 0;
     LOGPIXELSX:
-      Result := 96;
+      Result := 72;
     LOGPIXELSY:
-      Result := 96;
+      Result := 72;
     VERTRES:
       Result := Round(NSScreen.mainScreen.frame.size.height);
     NUMRESERVED: