--- a/gdk/x11/gdkxftdefaults.c	
+++ a/gdk/x11/gdkxftdefaults.c	
@@ -174,7 +174,8 @@ init_xft_settings (GdkScreen *screen)
     x11_screen->xft_rgba = FC_RGBA_UNKNOWN;
 
   if (!get_double_default (xdisplay, "dpi", &dpi_double))
-    dpi_double = 96.0;
+    dpi_double = (DisplayHeight(xdisplay, x11_screen->screen_num)*25.4)/
+		    DisplayHeightMM(xdisplay, x11_screen->screen_num);
 
   x11_screen->xft_dpi = (int)(0.5 + PANGO_SCALE * dpi_double);
 }
--