diff -up emacs-23.1/src/xterm.c.fontdpi emacs-23.1/src/xterm.c
--- emacs-23.1/src/xterm.c.fontdpi	2010-01-04 09:11:45.000000000 +0100
+++ emacs-23.1/src/xterm.c	2010-01-04 11:50:19.627777180 +0100
@@ -10380,17 +10380,31 @@ x_term_init (display_name, xrm_option, r
 				     dpyinfo->visual, AllocNone);
 
   {
-    int screen_number = XScreenNumberOfScreen (dpyinfo->screen);
-    double pixels = DisplayHeight (dpyinfo->display, screen_number);
-    double mm = DisplayHeightMM (dpyinfo->display, screen_number);
-    /* Mac OS X 10.3's Xserver sometimes reports 0.0mm.  */
-    dpyinfo->resy = (mm < 1) ? 100 : pixels * 25.4 / mm;
-    pixels = DisplayWidth (dpyinfo->display, screen_number);
-    mm = DisplayWidthMM (dpyinfo->display, screen_number);
-    /* Mac OS X 10.3's Xserver sometimes reports 0.0mm.  */
-    dpyinfo->resx = (mm < 1) ? 100 : pixels * 25.4 / mm;
+    /* If we are using Xft, check dpi value in X resources.
+       It is better we use it as well, since Xft will use it, as will all
+       Gnome applications. If our real DPI is smaller or larger than the
+       one Xft uses, our font will look smaller or larger than other
+       for other applications, even if it is the same font name (monospace-10
+       for example). */
+    char *v = XGetDefault (dpyinfo->display, "Xft", "dpi");
+    double d;
+    if (v != NULL && sscanf (v, "%lf", &d) == 1)
+      dpyinfo->resy = dpyinfo->resx = d;
   }
 
+  if (dpyinfo->resy < 1)
+    {
+      int screen_number = XScreenNumberOfScreen (dpyinfo->screen);
+      double pixels = DisplayHeight (dpyinfo->display, screen_number);
+      double mm = DisplayHeightMM (dpyinfo->display, screen_number);
+      /* Mac OS X 10.3's Xserver sometimes reports 0.0mm. */
+      dpyinfo->resy = (mm < 1) ? 100 : pixels * 25.4 / mm;
+      pixels = DisplayWidth (dpyinfo->display, screen_number);
+      mm = DisplayWidthMM (dpyinfo->display, screen_number);
+      /* Mac OS X 10.3's Xserver sometimes reports 0.0mm. */
+      dpyinfo->resx = (mm < 1) ? 100 : pixels * 25.4 / mm;
+    }
+
   dpyinfo->Xatom_wm_protocols
     = XInternAtom (dpyinfo->display, "WM_PROTOCOLS", False);
   dpyinfo->Xatom_wm_take_focus